Biology Test-10

If the vasa deferentia of man are surgically removed, Semen will be without sperms.

Sterilization provides a permanent and sure birth control. Vasectomy is very simple surgical method involving the cutting of the vas deferens in man. The vas deferens is removed or tied up through a small cut on the scrotum so that the sperms from the testicles cannot move out and hence semen released during ejaculation is without sperms.

On the onset of rainy season, frogs start breeding immediately. Male gather in shallow waters and starts croaking to attract females for mating.

The male mounts upon the back of the female and grasps her firmly with the help of copulatory pads. This process is known as Amplexus. Then female discharge about 2500 to 3000 eggs through her cloaca and male discharge sperms over these eggs, which results in fertilization.

Biosphere reserves are included in the in-situ conservation.

In situ conservation: The conservation of genetic resources in natural populations of plant or animal species, such as forest genetic resources in natural populations of tree species.

It is the process of protecting an endangered plant or animal species in its natural habitat, either by protecting or cleaning up the habitat itself or by defending the species from predators. E.g., hot spots, National parks, Sanctuaries, Biosphere Reserves, and sacred groves.

Major pollutants of ozone depletion are Aerosols.

Aerosols are vapour chemicals in the form of Fluorocarbons, Chlorofluorocarbons, Oxides of sulfur and nitrogen. These results in ozone depletion.

Its sources are-

1. Emission of jet and supersonic airplanes.
2. Refrigerators and air conditioners use aerosols as the refrigerant (Freon).
3. Solid plastic foams.

Inbreeding increases homozygosity. If we want to evolve pure line in any animal, then inbreeding is necessary.

Inbreeding eliminate harmful recessive traits by the selection process. It also helps in the accumulation of superior genes. This selection results in increased productivity of the inbred population. However, close inbreeding reduces fertility and even productivity. This is called inbreeding depression.

Archibald Garrod is known as the father of biochemical/ physiological genetics because he found that the correct explanation for the cause of many diseases like alkaptonuria, pentosuria, cystinuria and albinism which all are related to biochemical pathways involved in human physiology.

The pyramid of energy is always upright because the flow of energy is unidirectional from producer to consumer level. Producers have the maximum energy.

The energy gradually decreases at each trophic level of the food chain, as part of the energy is lost as heat and a major part of the energy is liberated during respiration. Only 10% of energy passes from one trophic level to the next trophic level.

The bacterium Bacillus thuringiensis (Bt) is widely used in biology as an insecticide. It produces proteins called Cry proteins, which are toxic to certain insects when ingested. These proteins have been harnessed for use as insecticides in agriculture to control pests such as caterpillars, beetles, and flies.

The Kinetochore is formed in the Metaphasestage of mitosis.In the metaphase stage of mitosis, the centromere joins the two sister chromatids.

The surface of the centromeres which holds the two sister chromatids of a chromosome is surrounded by a small disc-shaped structure called the kinetochore.

Given diagram is indicating the Pachytene stage of meiosis I.

Pachytene is the third stage of prophase I in meiosis I where the exchange of genetic material (DNA) takes place between the non-sister chromatids of the homologous chromosome. This process is known as crossing over.

Under normal aerobic conditions, pyruvic acid is oxidized to CO₂ and Water in cellular organelles, known asMitochondria.

In second stage of aerobic oxidation, pyruvic acid formed in glycolysis is transported to mitochondria, where it is oxidized to carbon dioxide and water. 34 out of 36 ATPs are also released in this process, giving mitochondria the name, ‘Power House of the Cell’.

Golgi apparatus package proteins into membrane bound vesicles inside the cell before they are sent to their destination.

Ribosomes are responsible for protein synthesis.

Chloroplast is responsible for conducting photosynthesis.

Indole-3-acetic acid (IAA, 3-IAA) is theMost abundant and basic, naturally occurring, plant hormone of the auxin class.

IAA is predominantly produced in the apical bud of and young leaves of plants and is known to be an inducer of cell division and elongation.

IAA, as well as most other auxins, are also known to act in concert with, or in opposition to, other plant hormones.

Example: The ratio of auxin to cytokinin in certain plant tissues determines initiation of root versus shoot buds.

The compact tissue is placed on the exterior of the bone and cancellous in the interior. The compact tissue is placed on the exterior of the bone and cancellous in the interior. On examining a section of any bone, it is seen to be composed of two kinds of tissue, one of which is dense in texture, like ivory, and is termed compact tissue; the other consists of slender fibers and lamella, which join to form a reticular structure; this, from its resemblance to lattice-work, is called cancellous tissue.

• Compact tissue. This is the harder, outer tissue of bones.
• Cancellous tissue. This is the sponge-like tissue inside bones.

The correct vertebral formula of vertebral column of human being isC${}_7$ Th${}_{1}2$ L${}_5$ S${}_5$ Co${}_4$.

The vertebrae are thirty-three in number and are grouped under the names cervical, thoracic, lumbar, sacral, and coccygeal. According to the regions they occupy there are seven in the cervical region, twelve in the thoracic, five in the lumbar, five in the sacral and four in the coccygeal.

Eutrophication in the lake is due to the presence of nitrogen and phosphorous.

To increase crop yield, fertilizers contain nitrates and phosphates.

When these get washed up into water bodies, the resulting increase of nitrate or phosphate in the water encourages algae growth, which forms a bloom over the water surface.

The algae leech the nutrient from the water body and kill aquatic life.

Eutrophication: It is an enrichment of water by nutrient salts that causes structural changes to the ecosystem.

Compounds that contain nitrogen and phosphorus (fertilizers) drive the eutrophication. These nutrients are generally not toxic.