Biology (Part-I) (UPSC)

Total Questions: 50

21. Assertion (A): Unsaturated fats are more reactive compared with the saturated fats. [2003]

Reason (R): Unsaturated fats have only single bonds in their structure.

(a) Both A and R are individually true and R is the correct explanation of A
(b) Both A and R are individually true but R is not the correct explanation of A
(c) A is true but R is false
(d) A is false but R is true

Correct Answer: (c) A is true but R is false

Solution:Assertion is true because unsaturated fats are more reactive compared with saturated fats due to multiple bonds present between carbon atoms. The reason is false because unsaturated fats have atleast double bond in their structure.

A saturated fat is a fat in which the fatty acids all have single bonds. An unsaturated fat is a fatty acid in which there is at least one double bond within the fatty acid chain.

22. Consider the following statements: [2003]

1. Molasses is a by-product of sugar production process.

2. Bagasse obtained in the sugar mills is used as a fuel in the boilers to generate steam for the sugar factories.

3. Sugar can only be produced from sugarcane as the raw material.

Which of these statements are correct?

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

Correct Answer: (a) 1 and 2

Solution:Molasses is by-product of sugar production process and bagasse of sugar used as a fuel in boilers for sugar factories. But sugar produced from sugar cane and also from sugar beet.

23. Assertion (A): Cellulose is used in making shatter-proof glass. [2006]

Reason (R): Polysaccharides are not soluble in water.

(a) Both 'A' and 'R' are individually true and 'R' is the correct explanation of 'A' .
(b) Both 'A' and 'R' are individually true but 'R' is not the correct explanation of A' .
(c) 'A' is true but 'R' is false.
(d) 'A' is false but 'R' is true.

Correct Answer: (a) Both 'A' and 'R' are individually true and 'R' is the correct explanation of 'A' .

Solution:Cellulose is not soluble in water that is why it is used in making shatter-proof glass. Cellulose is a poly saccharide.

24. Which one of the following parts of the pitcher plant becomes modified into a pitcher? [2007]

(a) Stem
(b) Leaf
(c) Stipule
(d) Petiole

Correct Answer: (b) Leaf

Solution:In pitcher plant, the lamina of leaf is modified into pitcher and the leaf apex gives rise to a coloured lid for attracting the insects.

25. Which of the following types of light are strongly absorbed by plants? [2007]

(a) Violet and orange
(b) Blue and red
(c) Indigo and yellow
(d) Yellow and violet

Correct Answer: (b) Blue and red

Solution:Photosynthesis occurs between wavelengths of about 400 nm and 750 nm. Red and blue colour wavelength is categories in this wavelength. So, plants absorb these colours. Photosynthesis does not occur in the infra-red or in ultraviolet light.

26. Consider the following : [2008]

1. Rice fields

2. Coal mining

3. Domestic animals

4. Wet lands

Which of the above are sources of methane, a major greenhouse gas?

(a) 1 and 4 only
(b) 2 and 3 only
(c) 1, 2 and 3 only
(d) 1, 2, 3 and 4

Correct Answer: (d) 1, 2, 3 and 4

Solution:Rice fields, coal mining, domestic animal and wet lands all are the sources of methane.

27. Which one of the following is an insectivorous plant? [2008]

(a) Passion flower plant
(b) Pitcher plant
(c) Night queen
(d) Flame of the forest

Correct Answer: (b) Pitcher plant

Solution:Pitcher plant is an insectivorous plant. It feeds on living creatures including insects and small mammals. These plant attracts the prey with a smell of rotting meat. The victim is dissolved by plant enzymes.

28. Consider the following statements about probiotic food: [2008]

1. Probiotic food contains live bacteria which are considered beneficial to humans.

2. Probiotic food helps in maintaining gut flora.

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:Probiotics are the living microorganisms that are healthy for host organism. Lactic acid bacteria, Bifido bacteria are common type of microbes used as probiotics. Certain yeast and Bacilli may also useful. Probiotics are commonly consumed as a part of fermented food with specially added active live cultures such as yoghurt or as dietary supplements.

29. Consider the following statements: [2009]

1. Sweet orange plant is propagated by grafting technique.

2. Jasmine plant is propagated by layering technique.

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:Grafting is a most common method of vegetative propagation. In this method, parts of two plants are joined in such a way that they grow as a one plant. Sweet orange plant is propagated by grafting technique. Layering is another type of vegetative propagation. In this method, roots are artificially induced on the stem branches before they are detached from the plant for propagation. Jasmine plant is propagated by this technique.

30. In making the saffron spice, which one of the following parts of the plant is used? [2009]

(a) Leaf
(b) Petal
(c) Sepal
(d) Stigma

Correct Answer: (d) Stigma

Solution:Saffron is a spice obtained from the stigma of the flower of Crocus sativus Linnaeus.

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