Biology Test - 2

Reforestation refers to the replanting of trees on land that has previously had trees, but where these were cut down later. Reforestation is one of the remedies to combat deforestation. Because of the increasing loss of forests, many animals and plants are losing their habitat leading to a loss in biodiversity of species. Carbon dioxide levels in the atmosphere are on an ever increasing trend because of very less plant cover left to utilise the carbon dioxide. So, reforestation is the ultimate remedy for many environmental issues.

Hence, The correct answer is B.

Intestinal villi (singular: villus) are small, finger-like projections that extend into the lumen of the small intestine. ... Villi increase the internal surface area of the intestinal walls making available a greater ... They have a large surface area so there will be more efficient absorption of fatty acids and glycerol into the blood stream.

Hence, The correct answer is D.

The Taj Mahal is situated in Agra. The air in this place contains high levels of sulphur and nitrogen oxides. This is due to the large number of power plants and industries set up around this area. These have been a major cause for acid rain, which has reacted with the marble (calcium carbonate) the Taj Mahal is made of. This has resulted in a gradual damage to this wonderful structure, which even today, is a major spot attracting tourists from all around the world.

Hence, The correct answer is A.

Deforestation refers to the clearing of trees, transforming a forest into cleared land which directly leads to loss of wildlife habitat. Due to the loss of trees, the top fertile soil gets washed away during rains and it can also cause flood in highly deforested land. Deforestation plays several roles in flooding because trees prevent sediment runoff and forests hold the soil in place, reducing the movement of sediments that can shrink river channels downstream.

Hence, The correct answer is D.

Any condition that disrupts the movement of bilirubin from the blood to the liver and out of the body can cause Jaundice. Bilirubin is a waste product created when red blood cells are broken down. In the bloodstream it is transported to the liver, where it is combined with a digestive fluid called bile. This eventually passes out of the body in urine or stools. So that is why jaundice is a disorder of the digestive system. This is also the reason why our stools are yellow in color, usually.

Hence, The correct answer is D.

The Western Ghats is a Biodiversity Hotspot. This is because of high endemism in the region, which also increases species richness and biological diversity.

Hence, The correct answer is B.

Sterile Insect Technique (SIT) is a process by which sterile male pests are introduced into the pest population to trick females into unsuccessful breeding encounters, providing a form of birth control and reducing reproduction rates.

Gene transfer techniques can help produce modified plants which have been pre loaded with target-specific toxins, which will be toxic to only the targeted pest and no other form of life. B Gene introduced into the cotton plant to combat the cotton bollworm is one such example.

Natural pesticides are naturally occurring compounds from plants, animals, fungi and bacteria, which can act as pesticides. Many serve as repellents whereas some are toxic, though only to a narrow range of related pest species. Examples include citronella oil, garlic oil, neem oil, pongamia oil etc.

Hence, The correct answer is D.

Deforestation refers to the clearing of trees, transforming a forest into cleared land which directly leads to loss of wildlife habitat. Due to the loss of trees, the top fertile soil gets washed away during rains and it can also cause flood in highly deforested land. Deforestation plays several roles in flooding because trees prevent sediment runoff and forests hold the soil in place, reducing the movement of sediments that can shrink river channels downstream.

Hence option D is the correct answer.

Wildlife is conserved by both in situ and ex situ methods.

In situ or on-site conservation involves the conservation of genetic resources of natural populations of plant and animal species, such as from forests, National Parks and Biosphere Reserves.

Ex situ conservation involves the preservation of components of biological diversity outside their natural habitats, such as in Zoological Parks.

Hence, The correct answer is C.

Fat is largely digested in the small intestine. Bile salts of the bile break down fat droplets into many small ones by reducing the surface tension of fat droplets. This process is called emulsification. This increases lipase action on fat.

Hence, The correct answer is D.

The duodenal wall of the small intestine secretes secretin and cholecystokinin (CCK).

Hence, The correct answer is C.

Atomic radioactive minerals are one of the natural sources of radioactive pollution. Radioactive elements like uranium, thorium, radium, isotopes of potassium (K-40) and carbon (C-40) are naturally occurring. Cosmic rays originating from the sun are also a natural source of radiation. Anthropogenic sources include radiations that are employed for diagnostic and therapeutic applications. X-rays are used in general radiology and CT scan. Gamma rays are used in the treatment of cancer. In all these procedures, we are exposed to varying doses of radiations.

Hence, The correct answer is A.

Under the IUCN Red List, the species marked as endangered are the next in line to extinction. These species are of high priority for wildlife conservators. Marking a species as endangered highlights the threat it has of facing complete extinction.

Hence, The correct answer is B.

Ecological diversity refers to the diverse array of ecosystems being seen in a huge geographical location. India for example, has deserts, tropical rainforests, mangroves, wetlands, coral reefs, estuaries and several other types of ecosystems. Therefore, India is said to have greater ecological diversity as compared to a Scandinavian country which mostly has cold, subpolar ecosystems.

Hence, The correct answer is B.

National Parks and Wildlife Sanctuaries have been established with the aim of conserving wildlife in their natural habitats. These places are protected by the forest department and they run several programmes to protect the endangered species.

Hence, The correct answer is A.