Biology Test-7

The immunity which is induced by vaccines is called as artificial active immunity. In the vaccination or immunization process, small amount of antigen (dead or weakened pathogen) is introduced into the body in the form of vaccine. This induces immune response and antibody formation against the antigen. As a result, body has sufficient antibodies to control the disease. For example: BCG vaccine for tuberculosis, oral polio vaccine 'sabin' etc.

Respiration in Limulus takes place through Book-gills. Book-gills are flap-like appendages that affect gas exchange within the water and seem to have their origin as modified legs. On the inside of each appendage, over 100 thin page-like membranes, lamellae, appearing as pages in a book, are where gas exchange takes place.

In Angiosperm, characters of flowers are used for classification because characters of flowers are conservative. Gymnosperms have no flowers and have naked seeds. Angiosperms are also called as flowering plants. Flowers are the reproductive organs for these plants. Examples of angiosperms include roses, tulips, tomatoes.

These fibres are cylindrical in shape is NOT the characteristic feature of Smooth Muscle Fibres.

Smooth muscle is an involuntary non-striated muscle found in the walls of hollow organs, such as the intestines, uterus and stomach. These fibres are spindle-shaped and are pointed at both ends.

They bear a single nucleus which is central. These are involuntary in nature and are also found in the tracts of the urinary, respiratory and reproductive systems. These muscles also play an important role in the ducts of exocrine glands.

The Eustachian valve (also known as the "valve of inferior vena cava") is a ridge of variable thickness in the inferior right atrium. During fetal life, the eustachian valve directs oxygen-rich blood from the inferior vena cava (IVC) toward the foramen ovale and away from the tricuspid valve. After the closure of the foramen ovale, it does not have a specific function.

In the genetic dictionary, there are 64 codons asGenetic code is a triplet.

There are 20 amino acids and each codon is a triplet; it consists of 3 nitrogenous bases constituting a particular amino acid. There are 4 nitrogenous bases ie. AUGC in the case of RNA. So, since each codon consists of 3 bases so total possibilities of combination would be 43=64. Now out of these 64 codons 61 codons code 20 amino acids. It is to be remembered that one

amino acid can be coded by one or more codons. The rest 3 ie. UGA, UAA, and UAG are termination codons ie. they don't code for any of the 20 amino acids.

EcoRl is an endonuclease enzyme isolated from strains of E.coli and is part of the restriction-modification system. In molecular biology, it is used as a restriction enzyme. It creates 4 nucleotide sticky ends with 5' end overhangs of AATT.

In the nomenclature of restriction enzymes, the first letter of the name of the genus in which the given enzyme is discovered is written first in the capital. It is followed by the first two letters of the species name of the organism and these three letters are generally written in italics. Hin and Hpa, both are produced from a single genus Haemophilus but from two different species i.e., H. influenza and H. parainfluenza respectively.

A genetically engineered micro-organism used successfully in bloremedlatlon of oil spills is a specles of pseudomonas.

Bioremediation is the process of using living micro-organisms to clean up a contaminated site. Organisms that produce enzymes capable of degrading petroleum are useful in cleaning up oil spills. Some common ones that break down oil are genetically engineered species of Pseudomonas and Azotobactera.

Pseudomonas infections are infections caused by a kind of bacteria called Pseudomonas that's commonly found in soil, water, and plants. The type that typically causes infections in people is called Pseudomonas aeruginosa.

The type of food chain in which decomposed organic matter is converted into energy rich compound is called Detritus food chain.

Detritus is nonliving organic matter inhabited by decomposing organisms. Ecosystems that are dependent on detritus as an energy and food source are known as detritus-based ecosystems. Detritus is very important as the base of food chains and for cycling of nutrients. In forest environments, the detritus, made up of leaf litter and other organic matter, serves as an energy source for decomposers, herbivores, and carnivores; as much as ten times more energy may flow through the detritus food chain as opposed to the grazing chain or pathway. Detritus also serves as the energy source for benthic ecosystems, sustaining the benthic food chain. In terrestrial ecosystems, detritus typically includes the leaf litter and other organic matter intermixed with soil, here known as humus.

Mitochondria storage energy in the form of ATP molecules & also responsible for cellular respiration.

Mitochondrion, membrane-bound organelle found in the cytoplasm of almost all eukaryotic cells (cells with clearly defined nuclei), the primary function of which is to generate large quantities of energy in the form of adenosine triphosphate (ATP). Mitochondria are typically round to oval in shape and range in size from 0.5 to 10 μm. In addition to producing energy, mitochondria store calcium for cell signaling activities, generate heat, and mediate cell growth and death.

This cell organelle is known as the “Power House of The Cell”. The main functions of cellular respiration are storge energy in the form of ATP molecules.

Ernst Mayr proposed the biological species concept, which defines species as groups of actually or potentially inter-breeding natural populations which are reproductively isolated from other such groups.

Reproductive isolation is a condition of speciation and the primary criterion of the biological species concept. In the well-known Ernst Mayr's definition, “species are groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups” (Mayr, 1942).

So, if both the assertion and the reason are true and the reason is a correct explanation of the assertion.

Stigma, ovule, embryo sac, placenta that are associated with the gynoecium.

Stigma is a part of pistil on which pollen grain lands. Each ovary may have many ovules, which have embryo sacs in them. Placenta is a tissue/ridge inside ovary to which ovules are attached.

Thalamus is the terminal part of the axis of flower which bears all floral appendages. Tapetum is the innermost layer of microsporangium while stamen is part of androecium.

The gynoecium is often referred to as the "female" portion of the flower, although rather than directly producing female gametes (i.e. egg cells), the gynoecium produces megaspores, each of which develops into a female gametophyte which then produces egg cells.