Self Studies

Biology Mock Test - 1

Result Self Studies

Biology Mock Test - 1
  • Score

    -

    out of -
  • Rank

    -

    out of -
TIME Taken - -
Self Studies

SHARING IS CARING

If our Website helped you a little, then kindly spread our voice using Social Networks. Spread our word to your readers, friends, teachers, students & all those close ones who deserve to know what you know now.

Self Studies Self Studies
Weekly Quiz Competition
  • Question 1
    5 / -1
    Fruit Production without fertilization is called-
    Solution

    Concept-

    • The fruit is a characteristic feature of flowering plants.
    • It is a mature or ripened ovary, developed after fertilization.
    • Generally, the fruit consists of a wall or pericarp and seeds.
    • The pericarp may be dry or fleshy. When the pericarp is thick and fleshy, it is differentiated into the outer epicarp, the middle mesocarp, and the inner endocarp.

    Explanation-

    The fruit is formed without fertilization of the ovary, it is called a parthenocarpy. 

    • Parthenocarpic fruit is seedless fruit.
    • Examples of parthenocarpic fruit are bananas, grapes, etc.

    Additional Information

    • Seeds, in general, are the products of fertilization, a few flowering plants such as some species of Asteraceae and grasses, have evolved a special mechanism, to produce seeds without fertilization, called apomixis
    • The female gamete undergoes development to form new organisms without fertilization. This phenomenon is called parthenogenesis.
    • Apogamy development of a sporophyte from a gametophyte without fertilization.
  • Question 2
    5 / -1
    Cleistogamous flowers are pollinated by
    Solution
    Key Points
    • Pollination is the transfer of pollen grains from the anther to the stigma of a flower.
    • Pollination can be divided into 3 types:
    1. Autogamy -
      • It is the transfer of pollen grains from the anther to the stigma of the same flower.
      • It requires the pollen release and stigma receptivity to be synchronous, to prevent cross-pollination.
      • The anthers and stigma lie close to each other to assure self-pollination.
      • The autogamous flowers can be of 2 types:
      1. Chasmogamous flowers have normal flowers with exposed anther and stigma.
      2. Cleistogamous flowers do not open at all, thus assuring self-pollination and seed set.
      • Some plants like Oxalis, Viola and Commelina produce both chasmogamous and cleistogamuos flowers.
    2. Geitonogamy -
      • It is the transfer of pollen grains  from the anther to the stigma of a different flower of the same plant.
      • It is functionally cross-pollination as pollinating agents are involved.
      • It is genetically self-pollination as both male and female gametes come from the same plant.
      • Example - Maize, Castor.
    3. Xenogamy -
      • It is the transfer of pollen grains to the stigma of different plant.
      • It causes genetic variation and is a type of cross-pollination.
      • It is always found in unisexual plants where male and female flowers are borne on different plants.
      • Example - Papaya.

    Therefore, cleistogamous flowers do not need any agent of pollination as they are self-pollinated.

    Additional Information

    • Birds, insects and bats are biotic agents of pollination.
    • The flowers pollinated by them are usually large, colourful, fragrant and produce nectar.
    • These flowers provide nectar and pollen as floral rewards to the agents of pollnation.
    • They may also provide a safe place for them to lay eggs.
  • Question 3
    5 / -1
    In human female, the ovarian cycle begins when the 
    Solution

    Concept:

    • Ovarian cycle refers to the menstrual cycle in a human female.
    • Menstrual cycle refers to the cyclical events that occur in a female primates, starting from puberty.
    • The menstrual cycle in human females is about 28-30 days and only one ovum is released in each cycle.
    • This cycle is highly controlled by hormones secreted from the ovaries and the anterior pituitary gland.
    • The ovaries secrete estrogen and progesterone.
    • The hypothalamus stimulates the anterior pituitary to secrete Luteinizing hormone (LH) and Follicle stimulating hormone (FSH).

    Important Points

    Phases of Menstrual Cycle:

    1. Menstrual Phase -
      • It marks the beginning of each cycle.
      • The menstrual flow occurs and lasts for 4-5 days.
      • It is caused due to the breakdown of endometrium of uterus.
      • Blood along with clots come out of the vagina.
      • Follicles get surrounded by granulosa cells to form the secondary follicles.
      • This is stimulated by FSH and LH which are secreted by the anterior pituitary.
    2. Follicular Phase -
      • It may last from 6th to 12th day.
      • Primary follicles develop into Graafian follicles in the ovary.
      • It is also called Proliferative phase because the endometrium is regenerated through proliferation.
      • The hormones LH and FSH stimulate follicular development and estrogen secretion from the ovary.
    3. Ovulatory Phase -
      • It occurs mid-cycle around 13-15th day.
      • The Graafian follicle ruptures to release the ovum into the fallopian tube.
      • This process is called ovulation and is caused by a rapid increase in LH (LH surge).
    4. Luteal Phase -
      • The ruptured Graafian follicle forms the corpus luteum, which secretes progesterone.
      • Progesterone maintains the endometrium in anticipation of pregnancy.
      • Absence of fertilization results in degeneration of corpus luteum.
      • This leads to breakdown of endometrium, that marks the beginning of the next cycle.
  • Question 4
    5 / -1
    Cu++ released from copper releasing intra uterine devices, 
    Solution

    Concept:

    • Contraceptives are birth control devices that help in preventing unwanted pregnancies.
    • Various contraceptive methods can be divided into:
    1. Natural Methods -
      • These include natural ways by which the meeting of sperm and ovum can be avoided.
      • There are 3 major ways - Periodic abstinence, Coitus interruptus and Lactational amenorrhea.
    2. Physical Methods/ Barriers -
      • This is the method by which physical barriers are used to prevent pregnancy.
      • Males can use condoms, while females can use diaphragm, cervical caps or vaults.
      • They block the entry of sperms through the cervix.
    3. IUDs -
      • Intra-uterine devices are inserted into the uterus through the vagina.
      • These can be non-medicated, copper-releasing or hormone-releasing.
      • Examples - Lippes loop, CuT, Cu7, Progestasert.
    4. Oral Contraceptives -
      • This involves oral administration of contraceptives.
      • It is also known as oral pills.
      • They are usually small doses of progesterone or a combination of progesterone and estrogen.
    5. Surgical Methods -
      • This includes sterilization processes of tubectomy and vasectomy.
      • It is a terminal method and often irreversible.
      • It interferes with gamete transfer and thus prevent pregnancies.

    Important Points

    • Intra-uterine devices or IUDs are inserted into the uterus through the vagina by any medical professional only.
    • These can be of 3 basic types:
    1. Non-medicated -
      • These devices increase phagocytosis of sperms within the uterus.
      • Examples - Lippes loop.
    2. Copper-releasing -
      • They release Cu ions which suppress sperm motility and fertilizing capacity of sperms.
      • Examples - CuT, Cu7, Multiload 375.
    3. Hormone-releasing -
      • These make the uterus hostile and unsuitable for implantation.
      • Examples - Progestasert, LNG-20.

    Therefore, we can see that Cu ions released from IUDs suppress the sperm mobility.

  • Question 5
    5 / -1
    Which of the following is an Asexual method of reproduction?
    Solution

    The correct answer is Option[4] i.e All of the above.

    • Asexual Reproduction:
      • It is the process in which a new individual is formed by the involvement of a single parent with or without the involvement of the gamete formation.
      • The individuals produced are genetically and morphologically similar.
      • It occurs in unicellular organisms where cells divide by mitotic division and no fertilization takes place. The division occurs very rapidly.
    • Types Of Asexual Reproduction
      • Binary Fission-
        • It is seen in amoeba and euglena.
        • The parent cell undergoes mitosis and increases in size. The nucleus also divides.
        • Two identical daughter cells are obtained, each containing a nucleusProkaryotes like bacteria majorly reproduce by binary fission.
      • Budding-
        • In this, the offspring grows out of the body of the parent.
        • It remains attached to the parent until it matures.
        • After maturation, it detached itself from the parent and lives as an individual organism.
        • This form of reproduction is most common in Hydras.
      • Fragmentation-
        • In some organisms like Planarians, when the body of an organism breaks into several pieces each piece grows into an individual offspring. This is known as fragmentation.
        • It can occur through accidental damage by predators or otherwise, or as a natural form of reproduction.
        • In few animals such as seastar, a broken arm grows into a complete organism.
      • Regeneration-
        • It is a modified form of fragmentation and occurs mostly in Echinoderms.
        • When a part of an organism, like an arm, detaches from the parent body, it grows into a completely new individual. 
      • Parthenogenesis-
        • This is a form of asexual reproduction where the egg develops without fertilization.
        • This process occurs in bees, wasps, ants, aphids, rotifers, etc. Ants, wasps, and bees produce haploid males. Parthenogenesis has been observed in a few vertebrates such as hammerhead sharks, Komodo dragons, blacktop sharks when the females were isolated from the males.
  • Question 6
    5 / -1
    What do you mean by encystation?
    Solution

    The correct answer is None of the above.

    Key Points

    • In yeast, the division is unequal and small buds are produced that remain attached initially to the parent cell which, eventually gets separated and mature into new yeast organisms (cells).
    • Under the unfavourable condition, the Amoeba withdraws its pseudopodia and secretes a three-layered hard covering or cyst around itself.
    • This phenomenon is termed as encystation.

    Important Points

    • When favourable conditions return, the encysted Amoeba divides by multiple fission and produces many minute amoeba or pseudopodiospores; the cyst wall bursts out, and the spores are liberated in the surrounding medium to grow up into many amoebae.
    • This phenomenon is known as sporulation.

    Additional Information

    • Asexual reproduction is common among single-celled organisms, and in plants and animals with relatively simple organisations.
    • In Protists and Monerans, the organism or the parent cell divides into two to give rise to new individuals.
    • In these organisms, cell division is itself a mode of reproduction.
    • Many single-celled organisms reproduce by binary fission, where a cell divides into two halves and each rapidly grows into an adult (e.g., Amoeba, Paramecium).
  • Question 7
    5 / -1
    The embryo sac is bounded by the wall of _______.
    Solution

    Concept-

    • In angiosperm flower, the male and female reproductive structures, the androecium and the gynoecium differentiate and develop.
    • The gynoecium represents the female reproductive part of the flower.
    • The gynoecium may consist of a single pistil or may have more than one pistil.
    • Each pistil has three parts: the stigma, style, and ovary.

    Explanation-

    • The ovule is also known as integumented megasporangium.
    • The megasporangium is a small structure attached to the placenta by means of a stalk called funicle.
    • Each ovule has one or two protective envelopes called integuments.
    • Enclosed within the integuments is a mass of cells called the nucellus.
    • Cells of the nucellus have abundant reserve food materials.
    • Located in the nucellus is the embryo sac or female gametophyte.
    • The embryo sac develops from a single megaspore formed from the megaspore mother cell inside the megasporangium.

    Therefore, the embryo sac is bounded by the wall of megasporangium.

    Additional InformationEndosperm

    • It is the nutritive tissue for the developing zygote.
    • It may or may not be present in the mature seed.

    Megaspore

    • In a majority of flowering plants, one of the megaspores is functional while the other three degenerate.
    • Only the functional megaspore develops into the female gametophyte (embryo sac).
  • Question 8
    5 / -1
    The foetal ejection reflex triggers the release of which hormone?
    Solution

    Concept:

    • Vigorous contraction of the uterus at the end of pregnancy causes expulsion/delivery of the foetus. This process of delivery of the foetus (childbirth) is called parturition.

    Explanation:

    • Foetal Ejection reflex
    • The signals for parturition originate from the fully developed foetus and the placenta which induce mild uterine contractions called foetal ejection reflex.
    • This triggers the release of oxytocin from the maternal pituitary.
    • Oxytocin then acts on the uterine muscle and causes stronger uterine contractions, which in turn stimulates the further secretion of oxytocin.
    • The stimulatory reflex between the uterine contraction and oxytocin secretion continues resulting in stronger and stronger contractions.
    • This leads to the expulsion of the baby out of the uterus through the birth canal – parturition.


    Additional Information

    • Prolactin: It is also called lactotrophic hormone. It regulates the growth and milk formation of mammary glands.
    • Estrogen, or oestrogen: It is a sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics.
    • Relaxin as the name suggests is used to keep the smooth muscles of the uterus relaxed. It is secreted in large amounts during parturition.
  • Question 9
    5 / -1
    During fertilisation the sperm comes in contact with the _________ layer of the ovum?
    Solution

    Concept:

    • The mature ovum after release from the graffian follicle consists of three layers oocyte, zona pellucida and corona radiata.

    Explanation:

    • The process of fusion of a sperm with an ovum is called fertilisation.
    • During fertilisation, a sperm comes in contact with the zona pellucida layer of the ovum and induces changes in the membrane that block the entry of additional sperms.
    • Thus, it ensures that only one sperm can fertilise an ovum.
    • The secretions of the acrosome (Sperm cap) help the sperm enter into the cytoplasm of the ovum through the zona pellucida and the plasma membrane.
    • This induces the completion of the meiotic division of the secondary oocyte.
    • The second meiotic division is also unequal and results in the formation of a second polar body and a haploid ovum (ootid).
    • Soon the haploid nucleus of the sperms and that of the ovum fuse together to form a diploid zygote.

  • Question 10
    5 / -1
    What is correct for test tube baby?
    Solution
    Concept:
    • Test tube baby refers to a child which is conceived by in vitro fertilization.
    • It is one of the methods of assisted reproductive technologies (ART) that helps to deal with infertility.
    • The cause of infertility may be - physical, congenital, immunological, psychological, diseases or drugs.
    • Specialized infertility clinics help in diagnosis and corrective treatments of couples to enable them in conceiving.
    • Sometimes, medical assisted procedures are required for a couple to bear children.
    • These ART procedures aim to resolve the specific issue that is restricting pregnancy. 

    Key Points

    • In vitro fertilization (IVF) - It is the fertilization of sperm and ovum outside the body in laboratory conditions that is similar to that of the body.
    • This is also known as the test tube baby programme.
    • The ovum from the female and sperm from the male are collected.
    • The gametes are then induced to fertilize and form zygote under simulated conditions in the laboratory (test tube).
    • The next step is embryo transfer, where the fertilized zygote is transferred to the female body.
    • This may take place by 2 ways:
      • ZIFT - Zygote intra-fallopian transfer is the transfer of the embryo, with less than 8 blastomeres, into the fallopian tube.
      • IUT - Intra-uterine transfer is the transfer of embryo with more than 8 blastomeres into the uterus, where implantation takes place.
    • Therefore, fertilization of ova occurs in test tube whereas embryo development occurs in uterus.

    Additional Information

    • Some other ART methods:
      • GIFT - Gamete intra-fallopian transfer is the transfer of only gamete into the female uterus.
      • ICSI - Intra-cytoplasmic sperm injection is a method by which the sperm is directly injected into the ovum.
      • IUI - Intra-uterine insemination is the method in which semen from the male is artificially introduced into the uterus of the female.
  • Question 11
    5 / -1

    Which of the following statements is are correct?

    1. The testes are situated outside the abdominal cavity within a pouch called the scrotum.

    2. The scrotum helps in maintaining the high temperature of the testes (higher than the normal internal body temperature) necessary for spermatogenesis.

    Solution

    The correct answer is 1 only.

    Key Points

    • The male reproductive system is located in the pelvis region.
      • It includes a pair of testes along with accessory ducts, glands, and the external genitalia.
    • The testes are situated outside the abdominal cavity within a pouch called the scrotum. Hence statement 1 is correct.
      • The scrotum helps in maintaining the low temperature of the testes (2–2.5o C lower than the normal internal body temperature) necessary for spermatogenesis. Hence statement 2 is not correct.
    • In adults, each testis is oval in shape, with a length of about 4 to 5 cm and a width of about 2 to 3 cm.
    • The testis is covered by a dense covering. Each testis has about 250 compartments called testicular lobules.
    • Each lobule contains one to three highly coiled seminiferous tubules in which sperms are produced.
    • Each seminiferous tubule is lined on its inside by two types of cells called male germ cells (spermatogonia) and Sertoli cells.
      • The male germ cells undergo meiotic divisions finally leading to sperm formation, while Sertoli cells provide nutrition to the germ cells.
    • The regions outside the seminiferous tubules called interstitial spaces contain small blood vessels and interstitial cells or Leydig cells.
      • Leydig cells synthesize and secrete testicular hormones called androgens. Other immunologically competent cells are also present. 
    • The male sex accessory ducts include rete testis, vasa efferentia, epididymis, and vas deferens.
    • The seminiferous tubules of the testis open into the vasa efferentia through the rete testis.
    • The vasa efferentia leaves the testis and opens into the epididymis located along the posterior surface of each testis.
      • The epididymis leads to vas deferens that ascends to the abdomen and loops over the urinary bladder.
      • It receives a duct from the seminal vesicle and opens into the urethra as the ejaculatory duct.
      • These ducts store and transport the sperms from the testis to the outside through the urethra.
    • The urethra originates from the urinary bladder and extends through the penis to its external opening called the urethral meatus.

    Additional Information

    • The penis is the male external genitalia.
    • It is made up of special tissue that helps in the erection of the penis to facilitate insemination.
    • The enlarged end of the penis called the glans penis is covered by a loose fold of skin called the foreskin.
    • The male accessory glands include paired seminal vesicles, prostate, and paired bulbourethral glands.
    • Secretions of these glands constitute the seminal plasma which is rich in fructose, calcium, and certain enzymes.
    • The secretions of bulbourethral glands also help in the lubrication of the penis.
  • Question 12
    5 / -1
    Double fertilization is the process in plants that includes
    Solution

    Explanation:

    • The most important and unique characteristic of angiosperms is the participation of both male gametes in the act of fertilization. One male gamete fuses with the egg cell and forms the diploid Zygote. The process is called syngamy or generative fertilization. The  Zygote (2n)  develops into an embryo.
    • The other male gamete fuses with two polar nuclei (or secondary nucleus) to form the triploid primary endosperm nucleus. The process is known as a triple fusion or Vegetative fertilization. 
    • These two actions of fertilization are together called Double Fertilization.

     

      

    Additional Information 

    • Antipodal cells: These are three in number present at the chalazal end of the embryo sac. These usually degenerate before/soon after fertilization. Antipodal cells serve to provide nutrition to the pro-embryo

  • Question 13
    5 / -1
    Process of transcription in bacteria involves
    Solution

    Concept:

    • Transcription is the process of copying the genetic information from one strand of DNA onto the RNA.
    • It takes place with the help of the enzyme DNA-dependent RNA polymerase (RNA pol).
    • It takes place at a defined region of DNA that is known as the transcription unit.
    • A transcriptional unit can be recognized by the following:
      • Template strand - It acts as the template for RNA pol to act on and has 3'→5' polarity.
      • Coding strand - It has 5'→3' polarity and is used as a reference strand for denoting upstream or downstream of a gene.
      • Structural gene - It contains the nucleotide sequence that actually codes for the required RNA.
      • Promoter - It is the nucleotide sequence that acts as a binding site for RNA pol enzyme.
      • Terminator - It is the nucleotide sequence that defines the end of transcription.
    • The promoter is located upstream of the gene, while the terminator is located downstream of the gene.
    • Upstream and downstream indicate towards the 5'-end and the 3'-end of coding strand respectively.

    Important Points

    Process of Transcription in bacteria involves the following steps:

    • Initiation -
      • RNA pol enzyme binds at the promoter site of DNA with the help of sigma (σ) factor and initiates transcription.
    • Elongation -
      • The sigma factor is released and RNA pol moves along the DNA to untwist the DNA double helix.
      • RNA pol uses nucleoside triphosphates for polymerization of RNA that remains bound to the DNA in the transcription bubble.
      • Some of the newly synthesized RNA is released from the enzyme as a single strand.
      • Only a part of the RNA remains bound as DNA-RNA hybrid.
    • Termination -
      • When the RNA pol enzyme reaches the terminator region, RNA is unwound from the DNA.
      • It is carried out by the Rho (ρ) factor that binds to the terminator site.
      • The nascent RNA is released along with the enzyme.
      • The DNA double helix reforms and ρ factor dissociates, terminating the transcription process.

    Additional Information

    • Polyadenylation, capping and splicing are post-transcriptional processes that take place in eukaryotes to process the hn-RNA and form the mature mRNA.
  • Question 14
    5 / -1
    Which one of the following anticodons are used for the translation of t-RNA during the biosynthesis of hemoglobin in sickle cell anemic patients?
    Solution

    Concept:

    • Central dogma of molecular biology states that flow of genetic information takes place from DNA to RNA to proteins.
    • Transcription of DNA to RNA is based on the complementarity of their strands.
    • Proteins are formed from mRNA by the process of translation.
    • They are formed as polypeptides, which are chains of amino acids.
    • But no complementarity exists between the RNA and the proteins for translation to take place.
    • Here the Genetic Code, which is the triplet codon, directs the synthesis of amino acids.
    • Francis Crick suggested that there has to be a mechanism to read the codons and link it to the amino acid because amino acids themselves do not have any structural feature to do that.
    • This suggested the presence of an adapter molecule that can read the code as well as bind to a specific amino acid.
    • This molecule happens to be the amino acid-specific tRNAs.
    • Each tRNA has:
      • Acceptor arm - It binds a specific amino acid and is present at the 3'-end.
      • Anticodon loop - It carries the complementary bases (anticodon) of the genetic code that codes for the amino acid carried by that tRNA.

    Important Points

    • Sickle-cell anaemia is caused by a point mutation that causes a substitution of amino acid.
    • The β-globin chain of haemoglobin (Hb) has Glutamic acid at the 6th position of its peptide chain.
    • This Glutamic acid (Glu) is substituted by Valine (Val) due to the point mutation.
    • A single base pair of A-T in the normal Hb gene (HbA) is replaced by T-A in the mutated gene HbS.
    • So the codon in the mRNA changes from GAG to GUG.

    Explanation:

    • We can see from the above diagram that patients with sickle-cell anaemia will have one codon different from normal people, which is the GUG codon.
    • For the translation of this GUG codon, the anticodon on the tRNA should be CAC.
    • This is based on the complementarity of bases, as suggested by Watson and Crick.
    • G always pairs with C and U with A.

    Therefore, CAC will be the anticodon in tRNA for biosynthesis of haemoglobin in sickle-cell anaemia patients.

  • Question 15
    5 / -1
    Natural parthenogenesis occurs in
    Solution

    Concept:

    • Reproduction is the biological process in which the organism gives rise to young ones or offspring similar to itself. It is responsible for the continuity of species generation after generation.
    • Reproduction is mainly divided into two types:
    1. Sexual reproduction
    • Involves the formation of the male and female gametes, either by the same individual or by different individuals of the opposite sex.
    • These gametes fuse to form the zygote which develops to form the new organism. Eg. Mammals

           2. Asexual reproduction:

    • The reproduction in which an offspring is produced by a single parent without the fusion of gametes is called asexual reproduction. (E.g. Amoeba, Hydra)
    • The offspring are exact replica of their parents and genetically identical.
    •  Asexual reproduction is of many types: Sporulation, Fission, Fragmentation. Budding, Plasmotomy, vegetative propagation, Apomixis & Parthenogenesis

    Explanation:

    • Parthenogenesis: Development of unfertilized egg or ovule into a new organism. It occurs in both plants & animals
    • Examples: Honeybee, Rotifers, Some lizards & birds

    Natural Parthenogenesis in Honeybee:

    • Every honey bee colony comprises a single queen, a few hundred drones, and several thousand worker castes of honey bees.
    • The drones are male bees with no sting.
    • The drones are produced by unfertilized eggs of the queen, or by those workers which take up the reproductive function due to the absence of a queen in a colony.
    • Thereby In the honeybee colony, the drones are produced by unfertilized eggs and show natural parthenogenesis

    Important Points

    • The drones produced by the unfertilized eggs impregnate the Queen bee to produce the female offspring thus, in a honeybee colony females are produced by the fertilized eggs while male drone are formed by the unfertilized eggs
  • Question 16
    5 / -1
    In a DNA molecule, hydrogen bonds are formed between which of the following?
    Solution
    Key Points
    • Deoxyribonucleic acid or DNA is a polynucleotide of deoxyribonucleotides.
    • Ribonucleic acid or RNA is a polynucleotide of ribonucleotides.
    • Thus nucleotides are the basic units of these molecules.
    • A nucleotide has 3 components -
    1. Pentose sugar - It is ribose in RNA and deoxyribose in DNA.
    2. Nitrogenous base - It is a nitrogen-containing molecule with the properties of a base. It is of 2 types: 
      1. Purine - It includes Adenine (C) and Guanine (G).
      2. Pyrimidine - It includes Cytosine (C), Thymine (T) and Uracil (U).
    3. Phosphate group
    • Thymine is present only in DNA and gets replaced by Uracil in RNA.
    • Therefore, a DNA strand will contain A, T, G and C bases.

    Important Points

    • According to Watson and Crick (1953), DNA is a double helical structure with the following features:
      • It is made up of 2 polynucleotide strands.
      • The two chains have anti-parallel polarity: one has 5'→3' and the other has 3'→5'.
      • The bases of two strands project inside and pair through H-bonds and form base pairs.
      • Adenine pairs with Thymine by 2 H-bonds and Guanine with Cytosine by 3 H-bonds.
      • Thus, purine is always paired with pyrimidine, creating uniform distance between both strands.
      • It is a right-handed helix (clockwise) with a pitch of 3.4nm and about 10bp in each turn.
    • Therefore, hydrogen bonds are formed between the two opposing strands of a double-stranded DNA.

    Additional Information

    • Phosphodiester linkage -
      • It is formed between two adjacent nucleotides in a DNA molecule.
      • The nucleotides are linked together by 3'-5' phosphodiester linkage.
      • This forms a dinucleotide and further additions of nucleotides would produce a polynucleotide.
    • N-glycosidic linkage -
      • It links the nitrogenous basesto the deoxyribose, which is the pentose sugar in the DNA strand.
      • This linkage forms the nucleoside.
      • The nucleosides are named as deoxyadenosine, deoxyguanosine, deoxycytidine or deoxythymidine.
    • Phosphoester linkage -
      • It links the 5'-OH of a nucleoside to the phosphate group.
      • This linkage forms the corresponding deoxynucleotide.
  • Question 17
    5 / -1
    Which of the following not a characteristic of Genetic code?
    Solution

    Concept:

    • codon is a sequence of three DNA or RNA nucleotides that encode for a specific amino acid or stop signal during protein synthesis (Translation).
    • The full set of codons is called the genetic code and each codon encodes for a single amino acid.
    • The genetic code includes a Total of 64 possible permutations, or combinations, of three-letter nucleotide sequences that can be made from the four nucleotides

    Explanation:

    Each codon in genetic code codes for a specific amino acid i.e. genetic code is not ambiguous in nature

    The salient features of genetic code are as follows:

    1. The codon is a triplet. 61 codons code for amino acids and 3 codons do not code for any amino acids, hence they function as stop codons.
    2. Some amino acids are coded by more than one codon, hence the code is degenerate
    3. The codon is read in mRNA in a continuous fashion. There are no punctuations.
    4. The code is nearly universal: for example, from bacteria to human UUU would code for Phenylalanine (phe). Some exceptions to this rule have been found in mitochondrial codons, and in some protozoans.
    5. AUG has dual functions. It codes for Methionine (met), and it also acts as an initiator codon.
    6. UAA, UAG, UGA are the terminator codons.

             Table showing codons coding for different amino acids

     

  • Question 18
    5 / -1
    Which part of gene is not available in mature mRNA?
    Solution

    Concept-

    • RNA was the first genetic material.
    • DNA has evolved from RNA with the chemical modifications that make it more stable.
    • RNA is made up of only one polynucleotide chain i.e. RNA is single-stranded.
    • The process of copying genetic information from one strand of the DNA into RNA is termed transcription.

    Explanation-

    • By transcription split, the gene produces an RNA that contains coding (exon) and non-coding (intron) sequence and called hn RNA. This hn RNA is unstable.
    • By capping and tailing, now it becomes stable.
    • By the process of RNA splicing, hn-RNA produces functional mRNA that is exonic RNA.

    Introns or intervening sequences do not appear in mature or processed RNA.

    Additional Information

    • DNA being double-stranded and having complementary strand further resists changes by evolving a process of repair. 
    • DNA and RNA are genetic material.
  • Question 19
    5 / -1
    The crossing over frequencies between the genes A and B, A and C and B and C are 8%, 15% and 23% respectively. What is the possible sequence of genes on chromosomes?
    Solution

    Concept-

    • Gene is the basic unit of inheritance.
    • Janssens was the first person to discover chiasma formation and related information of crossing over.
    • Crossing over is a wide-spread phenomenon among living organisms occurring in practically all higher plants and animals and has a great significance in genetics.
    • It brings a new combination of genes that are different from parents thus introducing variations.
    • The frequency of crossing over is used for building linkage maps or chromosome maps.

    Explanation-

    • Since % of crossing over (Recombinant frequency) ∝ distance between genes.
      • A-B (X) = 8% of crossing over 
      • A-C (Y) = 15% of crossing over
      • B-C (Z) = 23% of  crossing over
      • Z = X + Y   ;   23 = 8 + 15
      • It means that gene B and C are present at the ends and gene A is in middle.
    • Thus the sequence of genes on chromosomes can be B, A, C or C, A, B.
  • Question 20
    5 / -1
    Down’s syndrome is caused due to: ______.
    Solution

    Concept: 

    • A normal Human has 23 pairs of chromosomes (46 chromosomes) out of which 22 pairs are autosomes or allosomes  (Non - sex chromosomes), while the 23rd pair is the sex chromosome which is responsible for the hereditary changes.
    • One - One chromosome each in the sex chromosome pair comes from the maternal and paternal side respectively.
    • Any deviation from this normal arrangement may result in a disorder or syndrome.
    • These disorders may arise either by addition, deletion, or nonfunctioning of a single or multiple chromosomes.
    • Examples of such disorders are Turner syndrome, Edward's syndrome, Patau's syndrome, Klinefelter's syndrome, Down syndrome, etc.

    Explanation:

    • Down syndrome: It is a genetic disorder that occurs due to the trisomy of the 21 chromosome i.e. an extra copy of a chromosome gets added in the 21st set. 
    • This additional chromosome may be complete or some part of it is added.
    • It can be represented as 2n + 1
    • The extra copying occurs because chromosomes failed to separate during the cell division (Non-disjunction)
    • The symptoms include intellectual disability, physical growth delay, and distinct facial features.
    • Sometimes thyroid and heart diseases are also seen with this disorder.

        

    Additional Information

    • Trisomy 13 or Patau syndrome: It is a genetic disorder that occurs due to the trisomy of the 13 chromosome i.e. one additional chromosome gets added in the 13th set. Babies suffer severe mental and physical issues due to this syndrome and eventually die.
    • Edward's syndrome: It is caused due to the trisomy of the 18 chromosome. Babies suffering from this disorder are often born small and have heart defects.
    • Trisomy 16: It is a genetic disorder that occurs due to the trisomy of the 16 chromosome i.e. one additional chromosome gets added in the 16th set. It is the most common type of trisomy that leads to miscarriage of the fetus
  • Question 21
    5 / -1
    Birds are the example of _____ type of sex determination
    Solution

    Concept:

    • The chromosome theory of sex determination was worked by Wilson and Stevens.
    • There are two types of chromosomes- Sex chromosomes and autosomes.
    • The sex chromosome carries a gene that transfers from one generation to the next generation.
    • Sex has differentiated the organisms producing eggs from those organisms producing sperms.
      • The organisms producing eggs are known as females.
      • The organisms producing sperms are known as males.

    Explanation:

    • In birds, the total number of chromosomes is the same in both males and females.
    • But two different types of gametes in terms of the sex chromosomes, are produced by females, i.e., female heterogamety.
    • In order to have a distinction with the mechanism of sex determination, the two different sex chromosomes of a female bird have been designated to be the Z and W chromosomes.
    • In these organisms, the females have one Z and one W chromosome, whereas males have a pair of Z-chromosomes besides the autosomes.

    Additional Information

    OrganismSex determination type
    HumansXX/XY
    HoneybeeHaplodiploidy
    BirdsZW/ZZ
    InsectsXX/XO

    Mistake Points

    • Please note we always mention the sex chromosome of female first and then the male while writing the sex determination type.
    • Example - Sex determination type of man will be XX/XY type and NOT XY/XX type.
    • Hence, for female heterogamety we write ZW/ZZ type and NOT ZZ/ZW type.
  • Question 22
    5 / -1

    Skin colour in man is an example for

    Solution

    The correct answer is Polygenic inheritance.

    • Skin colour in man is an example of polygenic inheritance.

    Key Points

    • Polygenic inheritance:
      • It is a quantitative inheritance, where multiple independent genes have an additive or similar effect on a single quantitative trait.
      • It is also known as multiple gene inheritance.
      • Effects of polygenic inheritance in humans are different in skin and hair colour, height, eye colour, the risk for diseases and resistance, intelligence, etc.

    Additional Information

    • Multiple allelism is a condition where three or more alleles of a gene are present
      • An allele is one of two or more, type of the same gene at the same place on a chromosome.
      • Types of blood groups illustrate multiple allelism.
    • Pleiotropism is the condition in which a single gene controls more than one phenotypic traits in the same organism.
    • Sex-linked inheritance:
      • It is related to special pair of chromosomes known as the sex chromosomes.
      • They are of type X and Y.
      • Thomas Hunt Morgan proposed the Sex-linked inheritance
  • Question 23
    5 / -1
    Thalassemia is an autosomal recessive disorder of man. You have sampled a population where 16% of the people are affected with the disease. What will be the frequency of heterozygotes, assuming random mating in the population?
    Solution
    Hint
    • It is based on Hardy-Weinberg equation: p2 + q2 + 2pq = 1

    Key Points

    • G.H. Hardy and Wilhelm Weinberg independently described the basic principle of population genetics that is known as the Hardy-Weinberg principle.
    • It states that allele frequencies in a population remains constant from generation to generation.
    • The gene pool remains constant and is referred to as genetic equilibrium or Hardy-Weinberg equilibrium.
    • Gene pool - It is the total of all genes and alleles in a population.
    • This is supported by a mathematical equation that can be used to calculate genotype frequencies in a population at equilibrium.

    Important Points

    Concept:

    • Thalassemia is an autosomal recessive disorder, meaning the disease is expressed only in homozygous recessive condition.
    • If we assume the dominant and recessive alleles as A and a, the genotypic conditions will be:
      • AA - Homozygous dominant
      • aa - Homozygous recessive
      • Aa - Heterozygous
    • According to Hardy-Weinberg equation,

    Sum of all allelic frequencies = 1

    Therefore, p2 + q2 + 2pq = 1

    or, (p + q)2 = 1

    where, p and q represent the frequencies of the alleles A and a respectively.

    • Thus, the specific genotype frequencies are represented as:
      • p2 - AA
      • q2 - aa
      • 2pq - Aa

    Calculation:

    • It is given that the frequency of affected people is 16% or 0.16.

    Therefore, q2 = 0.16

    or, q = 0.4

    Now, (p + q)2 = 1

    or, p = 1 - q = 1 - 0.4 = 0.6

    Therefore, 2pq = 2 × 0.6 × 0.4 = 0.48 or 48%

    • Thus, the frequency of heterozygotes will be 48%.
  • Question 24
    5 / -1
    In 1953 S. L. Miller created primitive earth conditions in the laboratory and gave experimental evidence for the origin of the first form of life from preexisting non-living organic molecules. The primitive earth conditions created include:
    Solution

    Concept:

    • Different theories were given to explain the origin of life like the theory of special creation, the theory of spontaneous generation & the theory of chemical evolution.
    • The theory of chemical evolution was proposed by Oparin Haldane.
    • According to this theory, the first form of life could have come from pre-existing non-living organic molecules (e.g. RNA, protein, etc.) and that formation of life was preceded by chemical evolution, i.e., the formation of diverse organic molecules from inorganic constituents.

    Explanation:

    • The conditions on primitive earth at that time were – high temperaturevolcanic storms, reducing atmosphere containing CH4NH3, etc.
    • Two scientists S.L. Miller and H.C. Urey conducted an experiment in the year 1953 and proved the theory of chemical evolution. 
    • They created conditions similar to primitive earth in the laboratory, thereby the correct option is ''high temperature, volcanic storms, reducing atmosphere containing CH4, NH3 etc.''


    Important Points

    Experimental evidence of chemical evolution:

    • In 1953, S.L. Miller, an American scientist created similar reducing environmental conditions on a laboratory scale.
    • He created electric discharge in a closed flask containing CH4, H2, NH3 and water vapour at 8000C.
    • He observed the formation of amino acids. In similar experiments, others observed, formation of sugars, nitrogen bases, pigment and fats.
    • Analysis of meteorite content also revealed similar compounds indicating that similar processes are occurring elsewhere in space. With this limited evidence, the first part of the conjectured story, i.e., chemical evolution was more or less accepted.

    Diagrammatic representation of Miller’s experiment

  • Question 25
    5 / -1
    Select the correct set of homologous organs - 
    Solution
    Key Points
    • Homologous structures refer to the similar structures that differ in functions.
    • Example - Forelimbs of man, wings of birds and flippers of whales.
      • They are all made of humerus, radius, ulna, carpels, metacarpels and phalanges.
      • Flippers are used for swimming, wings for flying and forelimbs of man for grasping.
    • These structures have evolved from a common ancestor.
    • They show divergent evolution, meaning that they have undergone evolutionary modifications to perform different functions due to varying needs.
    • Example - Thorns of Bougainvillea and tendrils of Cucurbita both evolved from branches by modification into thorns for protection and tendrils for support.
    • Homologous structures provide evidence in support of biological evolution.

    Important Points

    • Forelimb of man, wings of birds and flippers of whale: CORRECT
      • ​These are homologous organs because they have similar structures and different functions.
    • Forelimb of man, wings of insects and wings of birds: INCORRECT
      • ​These are not homologous because wings of insects membranous and not made of bones.
    • Forelimb of man, hind legs of horse, wings of birds: INCORRECT
      • ​The hindlegs of horse does not have same bone structure as the forelimbs of man or wings of birds.
    • Forelimb of man, tail of horse, wings of bat: INCORRECT
      • ​The tail of horse does not have similar bone structure as the forelimb of man or wings of bat.

    Additional Information

    • Analogous structures refer to different structures that perform similar functions.
    • It indicates convergent evolution, directed towards a common need.
    • Examples -
      • Sweet potato and potato are root and stem modifications respectively but both function as storage organ.
      • Wings of birds are made of bones and feathers while wings of butterfly are membranous, but both are used for flying.
  • Question 26
    5 / -1
    Which scientist gave the theory of mutation?
    Solution

    The Correct option is Hugo de Vries.

    Concept:

    Different Theories Related to Evolution

    Mutation Theory by Hugo:

    • Sudden variation in inherited characters is called Mutation. 
    • The Theory of mutation was given by Hugo by his observation of plants. 
    • He observed that some of the plants are different from their parent plants.
    • The causes of mutation are
      • Change in number of genes
      • Change in gene arrangement
      • Change in gene structure

    Lamarck Theory

    • Jean Baptiste Lamarck's theory is also known as the Theory of acquired character. 
    • With changing environmental conditions, more used organs get strengthened and less frequently used organs get disappeared.
    • This can be explained by the example of the Giraffe which earlier used to feed on grass and weeds but later due to desertification, tried to eat leaves of long plants. Thus, the neck of the Giraffe got longer with time. 

    Darwin Theory

    • Darwin gave the theory of natural selection.
    • Each species reproduces to maintain its race.
    • The species struggle for survival with changing environmental conditions.
    • The species adapts with the surroundings survives and rest extinctions. 

    Mendels Theory

    • Mendel used a number of contrasting visible characters of garden peas- round/wrinkled seeds, tall/short plants, white/violet flowers, and so on.
    • He took pea plants with different characteristics- a tall plant and a short plant, produced progeny from them and calculated the percentages of tall or short progeny. Note the diagram below:

  • Question 27
    5 / -1
    A patient is suspected to be suffering from Acquired Immuno Deficiency Syndrome (AIDS). Which diagnostic technique will you recommend for its detection
    Solution

    Concept:

    • AIDS stands for Acquired Immuno Deficiency Syndrome (AIDS)
    • It was first reported in the U.S.A in 1981.
    • It is caused by the Human Immunodeficiency Virus (HIV).
    • HIV belongs to the group retrovirus.
    • It has an RNA genome enclosed in an envelope.
    • Transmission of HIV occurs in the following ways:
    1. By sexual contact with an infected person.
    2. By transfusion of contaminated blood and blood products
    3. By sharing infected needles.
    4. From the infected mother to her child through the placenta.

    Explanation:

    • The enzyme-linked immunosorbent assay (ELISA) tests a patient's blood sample for AIDS antibodies.
    • ​This test can be used to determine if you have antibodies related to certain infectious conditions.
    • Antibodies are proteins that your body produces in response to harmful substances called antigens.
    • An ELISA test may be used to diagnose:
    1. HIV, which causes AIDS
    2. Lyme disease
    3. pernicious anemia
    4. Rocky Mountain spotted fever
    5. rotavirus

    Additional Information

    • MRI: Magnetic resonance imaging (MRI) uses a large magnet and radio waves to look at organs and structures inside your body.
    • Health care professionals use MRI scans to diagnose a variety of conditions, from torn ligaments to tumors.
    • Medical ultrasound is a diagnostic imaging technique based on the application of ultrasound. It is generally used to see the internal structures such as tendons, muscles, joints, blood vessels, and internal organs of the human body.
    • The Widal test is a test for Typhoid (enteric fever). In this test bacteria causing typhoid is mixed with a serum containing specific antibodies obtained from an infected individual.
  • Question 28
    5 / -1
    Which of the following is NOT a feature of a cancer cell?
    Solution

    Explanation:

    • Cancer is one of the most dreaded diseases of human beings and is a major cause of death all over the globe. More than a million Indians suffer from cancer and a large number of them die from it annually.
    • In our body, cell growth and differentiation are highly controlled and regulated.
    • In cancer cells, there is a breakdown of these regulatory mechanisms.
    • Normal cells show a property called contact inhibition by virtue of which contact with other cells inhibits their uncontrolled growth. Cancer cells appear to have lost this property.
    • As a result of this, cancerous cells just continue to divide giving rise to masses of cells called tumours.
    • Tumours are of two types: benign and malignant.
    • The invasion of cancerous cells or tumours from one part of the body to the other parts through body fluid is called metastasis.
    • The malignant tumour shows metastasis and thus invade other body parts.

    Additional Information

    • Causes of Cancer: Cancer-causing agents are called carcinogens. These are of following types:
    1. Chemical agents: Aniline dyes, N-nitrosodimethylamine, benzopyrene, etc.
    2. Physical agents: Ionizing radiation like X-rays and γ rays, non-ionizing radiation like UV-rays
    3. Biological agents: Oncogenic viruses, some parasites
  • Question 29
    5 / -1
    Bhang and Ganja are 
    Solution

    Concept:

    • Addiction is the state of being given up on some habitdrugalcoholtobacco, etc.
    • Addiction is of three types- Drug abuse, Tobacco addiction, and Alcohol addiction.
    • Drug abuse is taking drugs for a purpose except for clinical use.
      • Drug abusers are likely to require drugs again and again.
      • Drugs alter perception, behaviour and consciousness.

    Explanation:

    • Cannabis sativa is commonly known as Hemp or Bhang plant.
    • Cannabinoids are a group of chemicals that are obtained from the inflorescences of the Cannabis plant.
    • Hashishcharas, ganja, and bhang are the different cannabis preparations.
    • Generally taken by inhalation and oral ingestion, these are known for their effects on the cardiovascular system of the body.
    • Ganja is prepared from the buds, twigs, stems, and leaves of the hemp plant.
    • Bhang is prepared using the flowering top of the hemp plant and it is also less potent than ganja.

    Thus, Bhang and Ganja are extracts of the hemp plant, Cannabis sativa.

    Additional Information

    Opioids:

    • Opiates or drugs obtained from opium or artificially produced substitutes that have opium-like effects.
    • They produce morphine-like effects.
    • Medically they are primarily used for pain relief, including anaesthesia.
    • Opioids are drugs, which bind to specific opioid receptors present in our central nervous system and gastrointestinal tract.
    • Example: codeine, morphine, heroin.

    Heroin:

    • Heroin is an opioid drug made from morphine.
    • It is a natural substance taken from the seed pod of the various opium poppy plants.
    • Heroin can be a white or brown powder, or a black sticky substance is known as black tar heroin. 
    • Heroin usage leads to euphoric, hallucinogenic, or sedating effects.
  • Question 30
    5 / -1
    Which of the following symbiotic microorganisms is nitrogen fixing?
    Solution
    Key Points
    • Nitrogen is an important mineral nutrient for plants, but they can not absorb atmospheric nitrogen.
    • Plants absorb nitrogen in the form of nitrates, ammonia or nitrites.
    • The conversion of atmospheric nitrogen into absorbable forms is carried out by microorganisms in the soil.
    • These are known as nitrogen-fixing microorganisms.
    • These are mostly bacteria and can be of 2 types:
      • Symbiotic - These maintain symbiotic relationships with plant roots, mostly leguminous roots.
      • Non-symbiotic - These are free-living, non-symbiotic bacteria that help in nitrogen-fixation by living in the soil around the roots.
    • The symbiotic nitrogen-fixing bacteria infect the plant roots and form root nodules.
    • They convert nitrogen to ammonia inside these nodules, which can then be used up by the plant.

    Important Points

    • Rhizobium -
      • It is a symbiotic bacteria that can fix nitrogen for leguminous plants.
      • It is a Gram-negative bacteria found in the soil.
      • The host plant provides carbohydrates as the energy source to the bacteria.
      • These symbiotic associations also improve the soil fertility.

    Additional Information

    • Azotobacter -
      • It is a non-symbiotic nitrogen-fixing bacteria.
      • It is frequently used as a biofertilizer due to this property.
      • It is used for non-leguminous plants like wheat, paddy, millets, etc.
    • Clostridium -
      • It is a free-living, Gram-positive bacteria that may be found in the soil.
      • It helps in nitrogen fixation but without getting associated with the plant.
    • Cyanobacteria -
      • Cyanobacteria or blue-green algae have some species like Nostoc and Anabaena that fixes nitrogen in soil.
      • They are also free-living and may be found in both terrestrial as well as aquatic habitats.
  • Question 31
    5 / -1
    The best method to overcome inbreeding depression is:
    Solution

    Concept:

    • Inbreeding refers to the mating between closely related individuals within the same breed for 4 - 6 generations.
    • Close inbreeding usually results in the reduction of fertility and productivity. This is called inbreeding depression.

    Explanation:

    • The best method to overcome inbreeding depression is Out-crossing.
    • It is a practice of mating animals of the same breed, that have no common ancestors on either side of their pedigree up to 4-6 generations.
    • The offspring is known as an out-cross.
    • It is done to increase milk production and growth rate in animals.
    • A single out-cross overcomes inbreeding depression.

    Additional Information

    • Outbreeding: It refers to the breeding of unrelated animals either of the same breeds but not having common ancestors (out-crossing) or of different breeds (cross-breeding) or even different species (interspecific hybridization)
    • Cross breeding: Cross breeding refers to the cross of superior males of one breed with superior females of another breed. It helps to accumulate the desirable genes of the two breeds into a progeny.
    • Interspecific hybridization: It refers to the crossing between male and female animals of two different species.
    • The progeny may or may not be of economic value.
    • For example, a mule was obtained by crossing a male donkey and a female horse.
  • Question 32
    5 / -1
    The process of improving the nutritional quality of food crops is termed as:
    Solution

    The correct answer is Biofortification.

    Key Points

    • Biofortification is the process by which the nutritional quality of food crops is improved through agronomic practices, conventional plant breeding, or modern biotechnology.
    • Biofortification of food crops is necessary to address the challenge of ‘hidden hunger.

    Mistake Points

    • The use of microbes to clean up contaminated soil and groundwater is called Bioremediation

    Important Points

    • Biofortification is breeding crops with higher levels of vitamins and minerals, or higher protein and healthier fats.
    • It is the most practical means to improve public health.
    • Breeding for improved nutritional quality is undertaken with the objectives of improving –
      • Protein content and quality
      • Oil content and quality
      • Vitamin content
      • Micronutrient and mineral content
  • Question 33
    5 / -1
    Which of the following part of a healthy plant should be used as explants to produce haploid plant?
    Solution

    Concept-

    • As traditional breeding techniques failed to keep pace with demand and to provide sufficiently fast and efficient systems for crop improvement, another technology called tissue culture.
    • It was learnt by scientists, during the 1950s, that whole plants could be regenerated from explants, i.e., any part of a plant taken out and grown in a test tube, under sterile conditions in special nutrient media.
    • This capacity to generate a whole plant from any cell/explant is called totipotency

    Explanation-

    • The pollen grains represent the male gametophytes. 
    • Pollen grains are haploid.
    • Explants, i.e., any part of a plant taken out and grown in a test tube.
    • Each of these plants will be genetically identical to the original plant from which they were grown, i.e., they are some clones.

    Therefore Pollen grain part of the healthy plant should be used as explants to produce haploid plants.

    Additional Information

    Meristem

    • Meristem is a localized region in which actual cell division occurs in plants.
    • The meristematic cells show the following features-
    • They are thin-walled and isodiametric without intercellular spaces.
    • The cytoplasm is dense and devoid of reserve food material.
    • Vacuoles are absent in meristematic cells, if present, they are small in size.

    Adventitious buds

    • When a bud grows from a position other than its normal position, it is called an adventitious bud.
  • Question 34
    5 / -1
    Which one of the following is the correct match of the product and the producer?
    Solution

    Concept:

    • Microbes play an important role for the production of industrial products.
    • They are used for fermented beverages, antibiotics, bioactive molecules as well as food products like cheese.
    • Microbes may include bacteria as well as fungi.

    Key Points

    • Blood cholesterol-lowering statins : Monascus purpureus - CORRECT
      • Monascus pupureus is a type of yeast that is used to produce blood cholesterol-lowering statins.
      • Statins inhibit the enzyme responsible for synthesis of cholesterol.
    • ​Antibiotics : Acetobacter aceti - INCORRECT
      • Acetobacter aceti is a bacterium that is used to obtain industrial acetic acid.
      • Antibiotics like Penicillin is obtained from the fungus Penicillium notatum.
    • Cyclosporin A : Streptococcus - INCORRECT
      • ​Cyclosporin A is produced from the fungus Trichoderma polysporum.
      • Cyclosporin A is used as an immunosuppressive agent in organ transplant patients.
      • Streptococcus bacteria are used industrially to produce Streptokinase, which is known as a 'clot buster'.
      • It is used to remove unwanted blood clots in the blood vessels of patients who have undergone heart attack.
    • Citric acid : Methanobacterium - INCORRECT
      • ​​Methanobacterium is a methanogenic bacterium that is used to produce biogas.
      • They can grow anaerobically on cellulosic material to produce methane (CH4), carbon dioxide (CO2) and hydrogen gas (H2).
      • They are often found in the rumen of cattle, which makes cow dung rich in these bacteria.
      • Citric acid is industrially produced by the fungus Aspergillus niger.
  • Question 35
    5 / -1

    Recombinant DNA technology (Genetic Engineering) allows genes to be transferred

    1. across different species of plants

    2. from animals to plants

    3. from microorganisms to higher organisms

    Select the correct answer using the codes given below.

    Solution

    The correct answer is 1, 2, and 3.

    GENETIC ENGINEERING (RECOMBINANT DNA TECHNOLOGY):

    1. The process of altering the chemistry of genetic material and then introducing it to the host organism so as to change the phenotype of the host organism is termed as Genetic Engineering.
    2. Genetic Engineering incorporates in itself these 3 processes: recombining DNA, gene cloning, and gene transfer.
    3. As the name suggests, Recombinant DNA technology is a technique through which DNA from different sources is combined to form a new DNA sequence.
    4. The recombined DNA from different species is then inserted into a host organism that produces a new genetic composition that is superior to the original DNA.
    5. The recombined DNA is inserted in such a way that it becomes the part of the chromosome that has a specific sequence known as the origin of replication.
    6. Tools of Recombinant DNA technology include Restriction Enzymes (molecular scissors), Cloning Vectors, and Competent Host.
    7. Steps of Recombinant DNA technology include Isolation of Genetic Material, Cutting of DNA at Specific Locations, Amplification of Gene of Interest using PCR, Introduction of the Recombinant DNA into the Host Cell/Organism, Obtaining the Foreign Gene Product, and Downstream Processing
    8. The technique finds application in many fields like: science, agriculture, medicine, and industry.

    Important Points

    • The first antibiotic-resistant recombinant DNA was constructed using the DNA of Salmonella typhimurium bacteria and was inserted into Escherichia coli.
    • This was accomplished by Stanley Cohen and Herbert Boyer in the year 1972.
  • Question 36
    5 / -1
    A gene of interest is cloned between Pst I and Pvu I sites in pBR322.The resultant plasmid has the ability to grow in medium containing ________ antibiotic.
    Solution

    Concept:

    • The pBR322 is the first artificial cloning vector developed in 1977 by Boliver and Rodriguez from E.coli plasmid.
    • The vector has the following sites:
    1. Origin of replication: This is a sequence from where replication starts and any piece of DNA when linked to this sequence can be made to replicate within the host cells. This sequence is also responsible for controlling the copy number of the linked DNA
    2. Selectable marker: In addition to ‘ori’, the vector requires a selectable marker, which helps in identifying and eliminating non-transformants and selectively permitting the growth of the transformants. Transformation is a procedure through which a piece of DNA is introduced in a host bacterium. the genes encoding
      resistance to antibiotics such as ampicillin, chloramphenicol, tetracycline, or kanamycin, etc., are considered useful selectable markers for E. coli. The normal E. coli cells do not carry resistance against any of these antibiotics.
    3. Cloning sites: In order to link the alien DNA, the vector needs to have very few, preferably single, recognition sites

    Explanation:

    • Selectable marker ampicillin has two restriction sites present Pst I and Pvu I 
    • So, when a gene of interest is cloned between Pst I and Pvu I sites in pBR322, the recombinant plasmid loses the ampicillin resistance due to the insertion of the gene.
    • When these transformants are plated in the medium containing ampicillin, they cannot grow as they have lost the ampicillin-resistant gene.
    • Now, they can only grow in the medium containing tetracycline because the gene coding resistance to tetracycline is still intact
    • Thus, option 3 is correct.

    The gene rop present in pBR322 cloning vector codes class 11 biology CBSE

    Ecoli cloning vector pBR322

  • Question 37
    5 / -1
    One of the insertional techniques for recombinant DNA is by making a competent cell. Which of the following is NOT used in this process?
    Solution
    Key Points
    • Competent cell refers to the ability of a cell to take up DNA.
    • As DNA is a hydrophilic molecule, it cannot pass through the cell membrane easily.
    • Thus, a host cell needs to be made competent for it to be transformed with the recombinant DNA (rDNA).
    • This is achieved by the following method:
      • Cells are treated with specific concentrations of divalent cations like Ca2+ from Calcium chloride (CaCl2).
      • This increases the efficiency with which DNA enters the bacterial cell.
      • Cells are incubated with rDNA on ice.
      • Cells are then briefly exposed to a heat shock at 42°C.
      • Then they are again transferred back to the ice.
      • This helps the cells to take up the DNA.
    • Thus, gold particles are not used in making competent host cells.

    Additional Information

    • Some other methods of inserting DNA into host cell:
      • Gene Gun - Plant cells are bombarded with high-velocity microparticles of gold or tungsten coated with DNA.
      • Microinjection - Recombinant DNA is directly injected into the nucleus of the cell.
      • Pathogen vectors - Disarmed pathogens can be used to infect the cells, allowing successful transfer of rDNA into host cell.
  • Question 38
    5 / -1
    Crystals of Bt toxin produced by some bacteria do not kill the bacteria themselves because
    Solution

    The correct answer is toxin is inactive.

    Key Points

    Crystals of Bt toxin

    • Cry proteins produced by some of the Bt strains do not kill the bacteria themselves because the toxin is inactive. Hence, statement 3 is correct.
    • In bacteria, the toxin is present in an inactive form, called prototoxin, which gets converted into active form when it enters the body of an insect.
    • It combines with the intestinal receptors of certain specific insects.
    • Bt toxin from Bacillus thuringiensis (Bt) is secreted in an inactive form and is activated in alkaline conditions of the gut of all worms.
    • The activated toxin bind to receptors on midgut epithelial cells of gallworm becomes inserted into the plasma membrane where they form pores leading to cell death through osmotic lysis.
    • It does not affect the bacteria itself as it is being secreted in an inactive form.
    • Bt toxin gene has been cloned from the bacteria and been expressed in plants to provide resistance to insects without the need for insecticides; in effect creating a bio-pesticide. Examples are Bt cotton, Bt corn, rice, tomato, potato and soybean etc.
    • Specific Bt toxin genes were isolated from Bacillus thuringiensis and incorporated into several crop plants such as cotton.
    • The choice of genes depends upon the crop and the targeted pest, as most Bt toxins are insect-group specific. The toxin is coded by a gene cryIAc named cry.
  • Question 39
    5 / -1
    "The use of bio-resources by multinational companies and other organisations without proper authorisation from the countries and people concerned without compensatory payment" is termed as 
    Solution

    The correct answer is Biopiracy.

    Key Points

    • Biopiracy:
      • It is the term used to refer to the use of bio-resources by multinational companies and other organisations without proper authorisation from the countries and people concerned without compensatory payment. Hence option 3 is correct.

    Additional Information

    • Bioremediation:
      • ​It is a process that uses mainly microorganisms, plants, or microbial or plant enzymes to detoxify contaminants in the soil and other environments.
    • Bioaccumulation:
      • ​It is the process of a chemical moving from the external environment into the organism from all possible exposure routes (water, sediment, soil, air, or diet) and is expressed as a bioaccumulation factor (BAF).
    • Biohacking:
      • It also known as human augmentation or human enhancement, is do-it-yourself biology aimed at improving performance, health, and wellbeing through strategic interventions. Some common biohacking techniques, like meditation and intermittent fasting, have been around since ancient times.
  • Question 40
    5 / -1
    Which of the following methods is most useful for the enzymatic amplification of specific gene segment of DNA?
    Solution

    Polymerase chain reaction ​is most useful for the enzymatic amplification of specific gene segments of DNA.

    Key Points

    • PCR stands for Polymerase Chain Reaction.
    • In this reaction, multiple copies of the gene (or DNA) of interest are synthesized in vitro using two sets of primers (small chemically synthesized oligonucleotides that are complementary to the regions of DNA) and the enzyme DNA polymerase.
    • The enzyme extends the primers using the nucleotides provided in the reaction and the genomic DNA as a template.
    • If the process of replication of DNA is repeated many times, the segment of DNA can be amplified approximately a billion times, i.e., 1 billion copies are made.
    • Such repeated amplification is achieved by the use of a thermostable DNA polymerase (isolated from a bacterium, Thermus aquaticus), which remains active during the high temperature-induced denaturation of double-stranded DNA.

    Additional Information

    Reverse transcription

    • Reverse transcription-polymerase chain reaction (RT-PCR) is a laboratory technique combining reverse transcription of RNA into DNA and amplification of specific DNA targets using polymerase chain reaction (PCR).
    • It is primarily used to measure the amount of a specific RNA.
    • This is achieved by monitoring the amplification reaction using fluorescence, a technique called real-time PCR or quantitative PCR (qPCR).

    DNA hybridization

    • Hybridization is the process of combining two complementary single-stranded DNA.
    • It allowing them to form a single double-stranded molecule through base pairing.

    Nucleotide sequencing

    • It is defined as a process of determining the order of nucleotides.
  • Question 41
    5 / -1

    Read the following statements and choose the correct option.

    Assertion(A) - Acclimatisation is temporary adjustment of organism to surroundings.

    Reason(R) - Hibernation is acclimatisation
    Solution

    Concept:

    Hibernation

    • It can be defined as a state of minimal functional activity and reduced metabolism in warm-blooded animals or endotherms.
    • Hibernation is most commonly related to a seasonal phenomenon in animals to avoid or survive through adverse climatic conditions.
    • The process of hibernation is characterized by lowering body temperature, slow breathing process with decreased heart rate, and low metabolic rate​
    • Hibernation is often referred to as winter sleep.
      • Examples: Skunks, Bees, Snakes, Groundhogs, Bears, Bats, etc.

    Acclimatisation and Adaptaion:

    • The process of changes that can occur in an organism over a short period that helps it to adjust to its surroundings is known as acclimatization.
    • Acclimatization is irreversible and temporary.
    • Adaptation is the changes in an organism over a long period, whereas acclimatization is changed over a short period.

    Explanation:

    • Acclimatization is the process of changes that occur in an organism over a short period that helps it adjust to its surroundings.
    • Two types of Acclimatization are heat and altitude acclimatization.
    • Hibernation is a way animals conserve energy to survive adverse weather conditions or lack of food.
    • Hibernation is winter sleep in which an animal passes the winter period in a dormant condition.
    • Hibernation is behavioral adaptation.

    Thus, from the above discussion, we can say that A is correct and R is not correct.

    Additional Information

     Aestivation:

    • It is a summer sleep to escape summer-related problems like heat and dissection.
    • Animals rest in a cool and moist place.
    • Examples: Earthworms, molluscs, arthropods, reptiles, amphibians, etc

    Camouflage:

    • It is an adaptation mechanism that allows tuning in with certain aspects of their surrounding environment.
    • Camouflage increases the chances of survival of an Organism in a particular habitat. They hide from their predator.
    • Examples: Caterpillar larvae, Black moth, African weaver birds, Mice, Stone flounder, a Flatfish
  • Question 42
    5 / -1
    Which one of the following is NOT a functional unit of ecosystem?
    Solution

    Concept:

    • The term ecosystem was coined by Sir A.G. Tansley (1935).
    • An ecosystem is the basic ecological unit in which living organisms interact among themselves and with their surrounding physical environment.
    • The entire biosphere is referred to as a global ecosystem.
    • Natural ecosystem - Forest, Grassland, Desert
    • Artificial ecosystem - Crop field, Aquarium

    Explanation:

    • The four functional units of an Ecosystem are:
    1. Productivity - The rate of biomass production per unit area over a time period by the plant during photosynthesis is called productivity. It is expressed in g-2 yr-1
    2. Decomposition - The process of breaking down complex organic matter into inorganic substances like CO2, water, and nutrients is called decomposition. The raw material of decomposition is detritus.
    3. Energy Flow - Except for the deep-sea hydrothermal vents, Sun is the only source of energy for all ecosystems on earth.
    4. Nutrient cycling - The movement of nutrient elements through various components (abiotic + biotic) of an ecosystem is called nutrient cycling or biochemical cycle.

    Additional Information

    • The vertical distribution of different species occupying different levels is called stratification. e.g., in a forest ecosystem, trees occupy the top vertical starter or layer, shrubs the second, and herbs and grasses occupy the bottom layers.  
  • Question 43
    5 / -1
    Mycorrhiza represents:
    Solution

    Explanation:

    • Mycorrhizae is a symbiotic association between a fungus and roots of higher plants.
    • The term mycorrhiza refers to the role of the fungus in the plant’s rhizosphere, its root system.
    • Mycorrhizal fungi allow plants to draw more nutrients and water from the soil.
    • They also increase plant tolerance to different environmental stresses.
    • They play a major role in the soil aggregation process and stimulate microbial activity. 

    Important Points

    Mycorrhiza is of two types:

    1. Ectomycorrhiza - In this, the fungus forms a covering around the plant's roots. In this way, a layer like structure is formed on the surface of the roots, which is called peudoparenchymatous sheath. Ex - Pinus, Abies, Eucalyptus and Oak
    2. Endomycorrhiza - In this the fungus does not form a layer on the roots of plants. They enter intracellularly in the roots. Intracellular fungal hyphae form branched structures in cells of roots called ''arubscule'' and unbranched structures called vesicles so these are also called Vesicular arbuscular mycorrhizal (VAM). Ex - Orchids

    Additional Information

    Epiphytes:

    • These are those plants that grow on the other plant surfaces.
    • They grow on other plant's surfaces so that they get shelter and exposure to the sunlight and can perform photosynthesis.
    • Eg. Orchid.
  • Question 44
    5 / -1
    The degradation of humus to release inorganic nutrients is called
    Solution

    Concept:

    • Decomposition is the process of breaking down a substance into its constituent parts. Decomposition of dead organic matter occurs in nature and it is also called decay or putrefaction.
    • Dead plant remains such as leaves, bark, flowers, and dead remains of animals, including fecal matter, constitute detritus, which is the raw material for decomposition. The important steps in the process of decomposition are fragmentation, leaching, catabolism, humification, and mineralization.

    Explanation:

    The correct option is ''mineralization''

    1. Fragmentation: Detritivores (e.g., earthworms) break down detritus into smaller particles. This process is called fragmentation.
    2. Leaching: By the process of leaching, water-soluble inorganic nutrients go down into the soil horizon and get precipitated as unavailable salts.
    3. Catabolism: Bacterial and fungal enzymes degrade detritus into simpler inorganic substances. This process is called catabolism
    4. Humification: Humification leads to the accumulation of a dark-colored amorphous substance called humus that is highly resistant to microbial action and undergoes decomposition at an extremely slow rate. Being colloidal in nature it serves as a reservoir of nutrients.
    5. Mineralization: The humus is further degraded by some microbes and the release of inorganic nutrients occurs by the process known as mineralization.

    Important Points 

    • It is important to note that all the fragmentation, leaching & catabolism in decomposition operate simultaneously on the detritus
    • Humification and mineralisation occur during decomposition in the soil
  • Question 45
    5 / -1
    Which among the following is the pioneer species during hydrarch succession?
    Solution

    Concept:

    • The sequential, gradual, and predictable changes in the species composition in an area are called succession or ecological succession.
    • The entire sequence of communities that successively changes in a given area is called sere(s).
    • The individual transitional communities are termed as seral stages or seral communities.
    • The community that is in near equilibrium with the environment is called a climax community.
    • The species that invade a bare area are called pioneer species.

    Explanation:

    • Hydrach succession takes place in wet areas or water, leading to successional series progress from hydric to mesic conditions.
    • The pioneer species are phytoplankton.
    • The phytoplanktons are replaced by free-floating angiosperms.
    • Then, rooted angiosperms invade sedges, grasses, and finally the trees.
    • At last, a stable climax forest is formed.
    • Aquatic habitat is converted into mesic habitat

      

  • Question 46
    5 / -1
    If 1000 J energy is available at the producer level in a food chain then the energy available at the secondary consumer level will be
    Solution

    Concept:

    • An ecosystem is the basic ecological unit in which living organisms interact among themselves and with their surrounding physical environment.
    • Except for the deep sea hydro-thermal ecosystem, the sun (sunlight) is the only source of energy for all ecosystems on earth.
    • Out of the total incident solar radiation, only 50% of it is photosynthetically active radiation (PAR).
    • Plants capture only 2-10 per cent of the PAR and this small amount of energy sustains the entire living world. So, there is the unidirectional flow of energy from the sun to producers and then to consumers.
    • Flow of energy - Sun → Producers → Primary Consumers → Secondary Consumers → Tertiary Consumers


    Explanation​:

    • The energy is transferred in an ecosystem in the form of food which is degraded and lose a major part of food energy as heat during metabolic activities, this can be explained by Lindeman’s 10 per cent law which says only 10% of energy is transferred from one trophic level to the next higher trophic level. 
    • Therefore, If 1000 J energy is available at the producer level in a food chain then the energy available at the primary consumer level ⇒ 10% of 1000J = 100 J and energy available to the secondary consumers  ⇒ 10% of 100 J = 10 J
       

  • Question 47
    5 / -1

    Consider the following pairs:

    Type of Diversity Example

    1. Genetic diversity: Mangroves Forests and Rain Forests

    2. Species diversity: Greater amphibian species in the Western Ghats than the Eastern Ghats

    3. Ecosystem diversity: Different varieties of Mango found in India

    Which of the pairs given above is/are correctly matched?

    Solution

    The correct answer is 2 only.

    Key Points

    • Genetics
      • Genetics is the branch of science that deals with the study of genes, genetic variations, and heredity in organisms.
      • Genes are made up of DNA and are a type of genetic instruction.
      • These instructions are used to make molecules and control the chemical reaction of life.
      • These are passed from parent to offspring.
    • Evolution
      • It is the process of heritable changes in the population of organisms over several generations.
      • The inherited traits are the expression of genes that are copied and passed on to the offspring during reproduction.
      • The heritable traits that are helpful for survival and reproduction become more common, while the harmful traits become rare.
      •  Genetics
        • Evolutionary genetics is the study of how genetics leads to evolutionary change.
        • It involves the study of the evolution of genome structure.
        • It is the sum of population genetics and evolution.
        • Genome evolution is the process by which the size and structure of the genome change with time.
        • The prokaryote genome evolves by mutation, transduction, and horizontal gene transfer.

    Important Points

    • Mangrove Forests and Rain forests are examples of ecosystem diversity.
    • Ecosystem diversity - refers to the diversity at the ecosystem level.
    • India, for instance, with its deserts, rain forests, mangroves, coral reefs, wetlands, estuaries, and alpine meadows has a greater ecosystem diversity than a Scandinavian country like Norway.

    Hence Pair 1 is incorrectly matched.

    • Species diversity - refers to the diversity at the species level.
    • The fact that the Western Ghats have a greater amphibian species diversity than the Eastern Ghats is an example of species diversity.

    Hence Pair 2 is correctly matched.

    • Genetic diversity – A single species might show high diversity at the genetic level over its distributional range.
    • Different varieties of Mangoes found in India are an example of Genetic diversity.
    • India has more than 50,000 genetically different strains of rice and 1,000 varieties of mango.

    Hence Pair 3 is incorrectly matched.

  • Question 48
    5 / -1
    Which one has the highest percentage of endangered species? 
    Solution
    Key Points
    • International Union for Conservation of Nature and Natural Resources or IUCN is the regulatory body that deals with biodiversity and the loss of biodiversity.
    • The IUCN Red List makes an assessment of the status of biodiversity to show how vulnerable a species is to get extinct.
    • Biodiversity is a dynamic environmental factor, which keeps changing with the environment and time.
    • As new species may get added as a result of speciation, existing species may become extinct, leading to loss of biodiversity.
    • Adverse human activities may increase the rate at which species become extinct, leading to mass extinctions.
    • IUCN Red List helps to check this drastic loss of biodiversity by introducing conservation strategies for the species which are more likely to get extinct in the near future.

    Important Points

    • According to IUCN, about 40,000 species are facing the threat of extinction.
    • Analysis has shown that extinctions are not random and some groups of organisms are more vulnerable than the others.
    • The variation of animals facing extinction:
      • Amphibians - 40%
      • Sharks and Rays - 37%
      • Conifers - 34%
      • Coral Reefs - 33%
      • Mammals - 26%
      • Birds - 13%
    • IUCN divides species into 9 categories:
      1. Not Evaluated
      2. Data Deficient
      3. Least Concern
      4. Near Threatened
      5. Vulnerable
      6. Endangered
      7. Critically Endangered
      8. Extinct in the Wild
      9. Extinct
    • The "Endangered" and "Critically Endangered" categories include all the species that are currently facing the threat of extinction.

    Therefore, the highest percentage of endangered species are of amphibians.

  • Question 49
    5 / -1

    Read the assertion and reason carefully to mark the correct option out of the options given below:

    Assertion: Motor vehicles equipped with catalytic converter should use unleaded petrol

    Reason: Lead in the petrol activates the catalyst

    Solution
    Key Points
    • Catalytic converters are used in vehicles to reduce emission of pollution causing gases.
    • They may use Platinum, Palladium and Rhodium as catalysts.
    • The exhaust passes through the catalyst chamber and converts unburnt hydrocarbons into CO2 and steam (H2O).
    • Carbon monoxide (CO) and nitrogen oxides are converted to CO2 and N2 respectively.
    • Pollutants like unburnt hydrocarbons, CO and nitrogen oxides are formed by the incomplete combustion of fuel in the vehicles.

    Important Points

    • Motor vehicles equipped with catalytic converter should use unleaded petrol: Assertion is TRUE
      • Vehicles using catalytic converters should use unleaded petrol because lead inactivates the catalyst.
    • Lead in the petrol activates the catalyst: Reason is FALSE
      • Lead inactivates the catalyst as it gets deposited on the catalyst.
      • This prevents the exhaust gases to come in contact with the catalyst, making it useless.
  • Question 50
    5 / -1
    Which of the following chemical compound causes Bio-magnification?
    Solution
    Key Points
    • Biomagnification is the accumulation of the increasing amount ​ of non-degradable pollutants through the food chain i.e., the concentration of toxicants increases at successive trophic levels.
    • It is caused because a toxic substance accumulated in an organism cannot be metabolized or excreted out.
    • It can only be passed on to the next trophic level, in which the concentration of the toxicant increases.
    • It is observed in aquatic food chains.
    • An aquatic food chain can be represented as:

    Phytoplankton → Zooplankton → Small Fish → Large Fish → Fish-eating birds

    • Phytoplanktons are the producers in the food chain, which are eaten by the zooplanktons and successively by fishes and then fish-eating birds.
    • Biomagnification is a well-known phenomenon for toxicants like mercury and DDT, which get released into water bodies.

    Explanation:

    • If we take the example of DDT, it starts with 0.003 ppb (parts per billion) in water.
    • Its concentration is found to increase to 0.04 ppm (parts per million) in zooplanktons.
    • It keeps increasing in successive trophic levels and we can find up to 25 ppm of DDT in the fish-eating birds.
    • Such high concentrations of DDT disturbs the calcium metabolism in birds.
    • It may cause thinning of eggshell and premature breaking of eggs, which eventually leads to decline in bird populations.

Self Studies
User
Question Analysis
  • Correct -

  • Wrong -

  • Skipped -

My Perfomance
  • Score

    -

    out of -
  • Rank

    -

    out of -
Re-Attempt Weekly Quiz Competition
Self Studies Get latest Exam Updates
& Study Material Alerts!
No, Thanks
Self Studies
Click on Allow to receive notifications
Allow Notification
Self Studies
Self Studies Self Studies
To enable notifications follow this 2 steps:
  • First Click on Secure Icon Self Studies
  • Second click on the toggle icon
Allow Notification
Get latest Exam Updates & FREE Study Material Alerts!
Self Studies ×
Open Now