Biology Test - 37

Human beings have an XX-XY sex-determination system.

In this, the males have XY sex chromosomes. They produce two types of gametes having X and Y chromosomes.

The females have XX chromosomes. They produce only one type of gamete having an X chromosome.

In DNA replication the newly added nucleotide is joined to the growing DNA strand by an enzymeDNA polymerase.

DNA polymerases are the enzymes that replicate DNA in living cells. They do this by adding individual nucleotides to the 3-prime hydroxl group of a strand of DNA. The process uses a complementary, single strand of DNA as a template.

Decrease in death rate and Development of agriculture are the primary factors for population explosion.

Population explosion means a sudden increase in the number of individuals in a particular species. The term is used to refer to the world’s human population. In India, Population explosion has become a severe matter of concern because the increase in population leads to poverty and illiteracy. 

Fungi is a large kingdom of over 72,000 species. They are achlorophyllous, heterotrophic, spore forming, non-vascular, eukaryotic organisms which contain chitin or fungal cellulose in their walls and possess glycogen as food reserve. They are major decomposers of many ecosystems and are associate of many organisms.

The "marker'' enzyme of lysosome isAcid phosphatase.

Lysosomes are small vesicles containing hydrolysing enzymes and surrounded by a single membrane. They are formed by Golgi apparatus and contain some 60 types of acid hydrolases for digestion of various materials, e.g., nucleases, proteases, lipases, glycosidases, phosphatases and sulphatases. Acid phosphatase is considered as a marker enzyme of lysosomes. Some of the other enzymes considered as marker enzymes for lysosomes are glucuronidase and N-acetyl-d-hexosaminidase, etc.

The correct name of  b, c, d and e are monocyte, basophil, lymphocyte and eosinophil.

White blood cells, also known as leukocytes, are immune cells that circulate in the blood and lymphatic system. There are 5 main types:

1. Neutrophils – main action against bacterial and fungal infections.
2. Monocytes – main action against bacterial infections.
3. Eosinophils – main action against parasitic infections.
4. Basophils – responsible for responses to allergens.
5. Lymphocytes – main action against viral infections.

Among the options, onlyCytokininis aplant hormone. Cytokinin helps in therapid cell division in plants.Cytokinin is largely present incoconut water.

Thetwo types of cytokinins are:

1. Adenine-type cytokinins.
2. Phenylurea-type cytokinins.

Cytokinins are involved inplant processes likecell division and shoot and root morphogenesis.Farmers use cytokininto increase crops.

• Melatoninis the hormone secreted by the Pineal gland. Melatonin is also called thehormone of darkness.Melatonin regulates thecircadian rhythmof the human body. The deficiency of melatonin causedsleeplessness.
• Gastrinis a peptide hormonereleased by theG cellsin thepyloric antrumof the stomach,duodenum, andpancreas.
• Cholecystokininis a peptide hormone secreted by the enteroendocrine cells in the duodenum.

Human blood grouping is an example of three alleles governing a character.

The human blood group (ABO blood group) shows multiple allelismwhereone character isgoverned by three alleles.The ABO blood group gene I (Iso agglutinogen) is present on the 9th chromosome. Gene I has three allelesIA, IB, IO.IAallele forms a sugar on the plasma membrane of RBC called a-antigen.IBallele forms a different sugar on the RBC called b-antigen.IOdoes not form any antigen.Alleles IAand IBare dominant over allele IObut co-dominant to each other.

The ABO blood grouping is used to determine the blood group of an individual based on the presence or absence of antigen A & B.

The segmentation of the pharyngeal endoderm has also been key to the evolution of pharyngeal metamerism. It is likely that endodermal segmentation is a deuterostome characteristic and that this basic pattern was sequentially modified and over time the more complex pharyngeal metamere of vertebrates emerged.

Smoking can cause lung disease by damaging your airways and the small air sacs (alveoli) found in your lungs.

The liver is the main organ affected by the toxic effects of aflatoxin. 

Mercury vapor, being highly volatile and lipid soluble, can cross the blood-brain barrier and the lipid cell membranes and can be accumulated into the cells in its inorganic forms. Also, methylmercury can pass through blood-brain and placental barriers, causing serious damage in the central nervous system.

DES is linked to rare cancer called clear cell adenocarcinoma (CCA) in a very small number of daughters of women who used DES during pregnancy. This cancer of the vagina and cervix usually occurs in DES-exposed daughters in their late teens or early 20s.