Biology (Part-I) (UPSC)

Total Questions: 50

31. Some species of plants are insectivorous. Why? [2010]

(a) Their growth in shady and dark places does not allow them to undertake sufficient photosynthesis and thus they depend on insects for nutrition.
(b) They are adapted to grow in nitrogen deficient soils and thus depend on insects for sufficient nitrogenous nutrition
(c) They cannot synthesize certain vitamins themselves and depend on the insects digested by them.
(d) They have remained in that particular stage of evolution as living fossils, a link between autotrophs and heterotrophs.

Correct Answer: (b) They are adapted to grow in nitrogen deficient soils and thus depend on insects for sufficient nitrogenous nutrition

Solution:Insectivorous plants prey insects because most of the insectivorous plants grow in those area where there is deficiet of nitrogen in nutrients so they catch insect to fulfil its need of nutrients.

32. Mon 863 is a variety of maize. It was in the news for the following reason. [2010]

(a) It is genetically modified dwarf variety which is resistant to drought
(b) It is a genetically modified variety which is pest resistant
(c) It is a genetically modified variety with ten times higher protein content than regular maize crop
(d) It is a genetically modified variety used exclusively for bio-fuel production

Correct Answer: (b) It is a genetically modified variety which is pest resistant

Solution:Mon 863 is genetically modified variety of maize, which is resistant of corn root worm.

33. Other than Jatropha curcas, why is Pongamia pinnata also considered a good option for the production of bio-diesel in India? [2010]

1. Pongamia pinnata grows naturally in most of the arid regions of India.

2. The seeds of Pongamia pinnata are rich in lipid content of which nearly half is oleic acid.

Which of the statements given above is/ are correct?

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Correct Answer: (c) Both 1 and 2

Solution:Pongamia Pinnata is adaptable to arid zones, and has a varied habitat distribution and able to grow in a variety of soils, it is native to humid and subtropical environment and grows naturally along coasts and river banks of India and Myanmar. It is nitrogen-fixing trees.

34. When the bark of a tree is removed in a circular fashion all around near its base, it gradually dries up and dies because? [2011-1]

(a) Water from soil cannot rise to aerial parts.
(b) Roots are starved of energy.
(c) Tree is infected by soil microbes.
(d) Roots do not receive oxygen for respiration.

Correct Answer: (b) Roots are starved of energy.

Solution:Phloem layer of tissue just below the bark is responsible for carrying food from leave to roots.

35. Consider the following kinds of organisms: [2013-1]

1. Bacteria

2. Fungi

3. Flowering plants

Some species of which of the above kinds of organisms are employed as biopesticides?

(a) 1 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3

Correct Answer: (d) 1, 2 and 3

Solution:All of them are employed as Biopesticides. Biopesticides, derived from natural materials like bacteria and fungi, offer an eco-friendly pest control alternative.

Examples include Bacillus thuringiensis for insects and Trichoderma species for plant diseases. While some plants produce pesticidal compounds, they're less common in pest management.

36. Consider the following organisms: [2013-1]

1. Agaricus

2. Nostoc

3. Spirogyra

Which of the above is/are used as biofertilizer/biofertilizers?

(a) 1 and 2
(b) 2 only
(c) 2 and 3
(d) 3 only

Correct Answer: (b) 2 only

Solution:Nostoc fix atmospheric nitrogen and are used as inoculations for paddy crop.

37. Fruits stored in a cold chamber exhibit longer storage life because : [2013-1]

(a) exposure to sunlight is prevented
(b) concentration of carbon dioxide in the environment is increased
(c) rate of respiration is decreased
(d) there is an increase in humidity

Correct Answer: (c) rate of respiration is decreased

Solution:Fruits respire. They give out ethylene which helps in ripening. When fruits are kept in cold storage the rate of ethylene production can be controlled and shelf life of fruits can be increased.

38. Many transplanted seedling do not grow because : [2013-1]

(a) the new soil does not contain favourable minerals
(b) most of the root hair grip the new soil too hard
(c) most of the root hairs are lost during transplantation
(d) leaves get damaged during transplantation

Correct Answer: (c) most of the root hairs are lost during transplantation

Solution:During a transplant the fine roots are destroyed due to the jostling during the uprooting process. These root hairs come under a shock. The plant which has been transplanted either takes time to readjust to the new soil or dries up and dies due to the root hair loss.

39. Which of the following leaf modifications occurs/occur in desert areas to inhibit water loss? [2013-1]

1. Hard and waxy leaves

2. Tiny leaves or no leaves

3. Thorns instead of leaves

Select the correct answer using the codes given below :

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Correct Answer: (d) 1, 2 and 3

Solution:To inhibit water loss or to conserve water most of the desert species have waxy leaves that keep them water proof when stomata are closed. Water is further conserved by reducing surface area so most succulents have few leaves or no leaves. Some desert plants have thorns instead of leaves. Thorns do not let the water go out.

40. Which one of the following is the process involved in photosynthesis? [2014-1]

(a) Potential energy is released to form free energy
(b) Free energy is converted into potential energy and stored
(c) Food is oxidized to release carbon dioxide and water
(d) Oxygen is taken, and carbon dioxide and water vapour are given out

Correct Answer: (b) Free energy is converted into potential energy and stored

Solution:In photosynthesis the free energy is converted into potential energy and stored.

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