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Part 120 – Biology Previous Year Questions

Q1. Interferons are synthesized in response to
(a) Bacteria (b) Fungi
(c) Mycoplasma (d) Virus
Ans: (d) Interferons (IFNs) are a group of signaling proteins made and released by host cells in response to the presence of pathogens, such as viruses, bacteria, parasites, or tumor cells. Interferon synthesis occurs primarily in response to viral single-stranded or double stranded RNA that are either the genetic material of RNA viruses or a product of viral transcription. Interferons are named for their ability to “interfere” with viral replication by protecting cells from virus infections.

Q2. The resources which are obtained from bio sphere and have life are :

(a) Potential resources
(b) Biotic resources
(c) Abiotic resources
(d) Renewable resources
Ans: (b) Biotic resources describe living or once living resources of a community; for example organisms, such as plants and animals. They are obtained from the biosphere and have life. The resources which are composed of non-living things are called Abiotic Resources. For example, water, minerals, metals, wind, solar energy etc.

Q3. The hydrophilic nature of DNA is due to the presence of :

(a) thymine base
(b) a number of hydrogen bonds
(c) phosphate group
(d) deoxyribose sugar
Ans: (b) The phosphate groups on DNA are ionic and charged. Each phosphate group on the DNA backbone is one unit of negative charge (-1). Charged molecules attract water and are hydrophilic. DNA has two hydrophilic polar external backbones made of sugars and phosphate groups joined by ester bonds.

Q4. Which of the following is used in the treatment of cancer ?

(a) Physiotherapy
(b) Chemotherapy
(c) Electrotherapy
(d) Psychotherapy
Ans: (b) Chemotherapy (or CTX) is a category of cancer treatment that uses chemical substances, especially one or more anti-cancer drugs (chemotherapeutic agents) that are given as part of a standardized chemotherapy regimen. Traditional chemotherapeutic agents are cytotoxic, that is to say they act by killing cells that divide rapidly, one of the main properties of most cancer cells.

Q5. Red rot of sugarcane is caused by :

(a) Alternaria alternata
(b) Phylophthora infestans
(c) Colletotrichum falcatum
(d) Cercospora personata
Ans: (c) Red rot disease is caused by the fungus Glomerella tucumanensis. An older name, Colletotrichum falcatum, is still preferred by some pathologists. Red rot occurs in various parts of the cane plant but it is usually considered a stalk and a seed-piece disease. Its symptoms are highly variable depending upon the susceptibility of the sugarcane variety and the environment.

Q6. The fleshy thalamus is edible in

(a) Apple (b) Tomato
(c) Orange (d) Mango
Ans: (a) Apple is a pome, a simple, fleshy but false fruit as it is surrounded by a fleshy thalamus which is edible while actual fruit lies within. Other examples are pear, loquat, etc.

Q7. The sense of balance is achieved by :

(a) Cerebrum equilibrium
(b) Thalamus equilibrium
(c) Cerebellum equilibrium
(d) Spinal chord equilibrium
Ans: (c) The cerebellum equilibrium controls the aspects of balance, equilibrium, and muscle tone, which are factors that provide for smooth movement and activity. Electrical impulses from the cerebellum stimulate muscles that are responsible for voluntary movement, and it works in coordination with the motor cortices of the cerebrum for this overall function.

Q8. Which of the following fuels causes minimum environmental pollution ?

(a) Kerosene (b) Diesel
(c) Coal (d) Hydrogen
Ans: (d) Most of environmental (air) pollution results from the burning of fossil fuels, such as coal, oil, natural gas, and gasoline to produce electricity and power. All these produce harmful CO2 or its variants. On the contrary, when hydrogen burns in air, it produces nothing but water vapor. It is therefore the cleanest possible as it doesn’t produce CO2.

Q9. Which one of the following features is absent in a virus ?

(a) reproduce within host cell
(b) presence of cell wall
(c) fully parasitic in nature
(d) presence of either DNA or RNA
Ans: (b) A virus has a simple structure. It has no internal cellular structure, no cell wall or cell membrane, just the protein coat that holds the string of nucleic acid. It is made only of a nucleic acid + a protein coat. A cell wall is a layer located outside the cell membrane found in plants, fungi, bacteria, algae, and archaea.

Q10. The colour of the carrots is due to the presence of

(a) Carotene
(b) Chlorophyll
(c) Phycocyanin
(d) Phycoerythirn
Ans: (a) Carotenes are photosynthetic pigments that are responsible for the orange colour of the carrot, for which this class of chemicals is named. Some carrots are yellow due to Anthocyanins. Carotenes are also responsible for the orange (but not all of the yellow) colours in dry foliage.

Q11. Wings of birds and insects are

(a) Xenologous (b) Homologous
(c) Paralogous (d) Analogous
Ans: (d) Wings of birds and insects are analogous structures used for flight in both types of organisms. But, they have no common ancestral origin at the beginning of their evolutionary development. They show similar function but show no similar structural relationship.

Q12. With which one of the following Jacobsons organ is related to ?

(a) Vision (b) Chewing
(c) Smelling (d) Hearing
Ans: (c) Jacobson’s organ, also called vomeronasal organ, is a patch of sensory cells within the main nasal chamber that detects heavy moisture-borne odour particles. It is a “sense of smell” receptor that is actually not receptive to ordinary odors.

Q13. Insectivorous plants grow in soil which is deficient in

(a) Nitrogen (b) Sodium
(c) Calcium (d) Magnesium
Ans: (a) Carnivorous or insectivorous plants grow in places where the soil is thin or poor in nutrients, especially nitrogen, such as acidic bogs and rock outcroppings. In this habitat, plants that have alternative strategies for obtaining essential minerals are at a competitive advantage. The capture of insects provides such plants with a supplemental source of essential nutrients.

Q14. Hind limbs thumping on ground by a rabbit is a behaviour related to

(a) Courtship
(b) Preparation for a duet
(c) Warning signal to members
(d) Surrender ot a stronger opponent
Ans: (c) A thump of either a single hind leg or both together shows the rabbit’s fear or displeasure over something. In any case, it shows the identification of some danger in the vicinity by the rabbit. The rabbit feels threatened by a danger, and warns the rest of his warren.

Q15. Rate of cooling depends on the

(a) Temperature difference between the body and the surroundings
(b) Nature of the radiating surface
(c) Area of the radiating surface
(d) All of these
Ans: (d) Newton’s Law of Cooling states that the rate of temperature of the body is proportional to the difference between the temperature of the body and that of the surrounding medium. When a body cools by radiation, then rate of cooling depends upon the following factors: l Nature of the radiating surface, that is, emissivity; l Area of the radiating surface; l Mass of the radiating surface; l Specific heat of the radiating body; l Temperature of radiating body and l Temperature of the surrounding.

Q16. The maximum fixation of solar energy is done by

(a) Protozoa (b) Bacteria
(c) Fungi (d) Green plants
Ans: (d) The maximum 20% of the input of solar energy falling on leaves is converted into chemical energy by green plants. Green plants utilize solar energy and synthesize sugar from CO2 and water through the process of photosynthesis. However, they are able to utilize only 3% of the light energy that strikes on their green parts; the rest is dissipated as heat.

Q17. Allantois of Embryo helps in

(a) digestion (b) respiration
(c) excretion (d) protection
Ans: (c) The allantois is the sac-like extra-embryonic membrane that removes waste from the embryo. As the embryo grows, so does the allantois, eventually pressing against the chorion. This allows the allantois to exchange oxygen and carbon dioxide with the air outside the eggshell. In addition, the allantois also serves as a disposal site for uric acid.

Q18. Which one of the following animals belongs to mollusca?

(a) Haliotis (b) Hare
(c) Hydra (d) Hyla
Ans: (b) Sea hares are molluscs. They belong to Phylum Mollusca and Class Gastropoda like snails. Like many other sea slugs (Subclass Opistobranchia), sea hares lack external shells as adults. Sea hares belong to Order Anaspidea.

Q19. Outside the nucleus DNA is found in

(a) Golgi bodies
(b) Mitochondria
(c) Ribosome
(d) Endoplasmic reticulum
Ans: (b) In eukaryotic (with nucleus) cells, the vast majority of DNA is found in the nucleus as discrete bodies called chromosomes. The exception to this being the small amount of DNA found in organdies outside the nucleus (mitochondria and chloroplasts). In human cells, more than 99% of the total DNA is nuclear genomic DNA and the remainder mitochondrial.

Q20. Animal protein is called first class protein because it is

(a) easily digestible
(b) delicious in taste
(c) cheaper in the market
(d) rich in essential amino acids
Ans: (d) Proteins from animals are called ‘first class’ proteins – they provide all the essential amino acids, including those that the body can’t make. Proteins from plants are ‘second class’ proteins.

Q21. Photoperiodism affects

(a) All of these
(b) Flowering
(c) Vegetative growth
(d) Fruiting
Ans: (a) Photoperiodism is the developmental responses of plants to the relative lengths of light and dark periods. It affects the vegetative growth as well as the time of flowering and fruiting in plants. For example, some annual plants may be made to complete their life cycle twice in a year, while others can be made to take on characteristics of everlasting flowering species and continue to produce flowers and fruits on an indefinite period, while in yet other species the plant may continue vegetative development indefinitely without flowering.

Q22. Match the following :
A. Ascorbic 1. Photosynthetic acid pigment
B. Chlorophyll 2. Quencher
C. Carotenoid 3. Enzyme D.Superoxide 4. Vitamin-C dismutase A B C D

(a) 4 1 2 3
(b) 4 2 1 3
(c) 2 4 1 3
(d) 4 1 3 2
Ans: (a) Ascorbic acid: also known as vitamin C; Chlorophyll: green photosynthetic pigment found in plants, algae, and cyanobacteria; Carotenoids: known to be potent quenchers of singlet molecular oxygen; Superoxide dismutase: an enzyme found in all living cells.

Q23. The least penetrating power ray is

(a) X-Ray (b) -Ray
(c) -Ray (d) -Ray
Ans: (b) Since alpha particles are high in ionizing power, it is difficult for them to penetrate matter thoroughly. This is because alpha particles are likely to ionize the first thing they come into contact with; thus, they hold a small range of penetrating power. Beta rays have intermediate; while, Gamma Rays and X Rays have maximum penetrating power.

Q24. Hydrogen peroxide is an effective sterilizing agent. Which one of the following product results when it readily loses active oxygen?

(a) Nascent Hydrogen
(b) Water
(c) Hydrogen
(d) Ozone
Ans: (b) Hydrogen peroxide (H2O2) is a water molecule with an extra oxygen atom. It is very unstable and breaks down readily into water and a single oxygen molecule. So in nutshell, when Hydrogen peroxide readily loses active oxygen, Water is formed.

Q25. X-rays can be used

(a) for cutting and welding of metals.
(b) to detect heart diseases.
(c) to detect defects in precious stones and diamonds.
(d) to detect gold under the earth.

Ans: (c) X-rays are used to detect and photograph defects of internal structure of a body such as metals, machine parts, cracks in wood, defects in diamonds and other precious stones, etc. They can reveal inhomogeneities— such as inclusions, lattice defects, etc in gems and stones.

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