Biology (Part-III) (UPSC)

Total Questions: 50

1. Match List-I with List-II and select the correct answer using the codes given below: [2001]

List-I (Achievement in genetics)	List-II (Scientists)
A. Discovery of transduction and conjugation in bacteria	1. Khurana
B. Establishing the sex-linked inheritance	2. Kornberg
C. Isolation of DNA polymerase from E. coli	3. Lederberg
D. Establishing the complete genetic code	4. Morgan
	5. Ochoa

Codes:

	A	B	C	D
(a)	4	3	2	1
(b)	3	4	1	5
(c)	4	3	1	5
(d)	3	4	2	1

Correct Answer: (d)

Solution:Transduction was discovered by Joshua Lederberg and Norton Zinder in 1951, while looking for a system of conjugation and recombination (chapter 4) in Salmonella typhimurium.

Morgan's conclusion that the white-eye trait followed patterns of sex chromosome inheritance was at once very specific and very grand.

The history of DNA polymerase is rooted in the work of Arthur Kornberg who in 1948 discovered that an enzyme he extracted from potatoes (nucleotide pyrophosphatase) could synthesise Nicotinamide adenine dinucleotide (NAD), a coenzyme found in all living cells.

Dr. Hargobind Khurana with other two scientist showed that RNA-the intermediate molecule between DNA and proteins - could form three letter 'words' with its chemical bases A, U, C and G and that these 'words' could be translated into a sequence of amino-acids, the building blocks of proteins.

2. Which of the following features of DNA makes it uniquely suited to store and transmit genetic information from generation to generation? [2001]

(a) Complementary of the two strands
(b) Double helix
(c) Number of base-pairs per turn
(d) Sugar-phosphate backbone

Correct Answer: (b) Double helix

Solution:Double helix structure of DNA transmits genetic information from generation to generation.

3. "Metastasis" is the process by which: [2001]

(a) cells divide rapidly under the influence of drugs
(b) cancer cells spread through the blood or lymphatic system to other sites or organs
(c) the chromosomes in cells nuclei are attached to the spindle before moving to the anaphase poles
(d) cancer cells are successfully inhibited to divide any further

Correct Answer: (b) cancer cells spread through the blood or lymphatic system to other sites or organs

Solution:Metastasis is the spread of cancer from its primary site to other places in the body (i.e. brain, liver). Cancer cells can break away from a primary tumour, penetrate into lymphatic and blood vessels, circulate through the blood stream and grow to a normal tissues in the body.

4. Match List-I with List-II and select the correct answer using the codes given below the lists : [2001]

List-I (Substance)	List-II (Physiological role)
A. Ptyalin	1. Converts angiotensinogen in blood into angiotensin
B. Pepsin	2. Digests starch
C. Renin	3. Digests proteins
D. Oxytocin	4. Hydrolyses fats
	5. Induces contraction of smooth muscles

Codes:

	A	B	C	D
(a)	2	3	1	5
(b)	3	4	2	5
(c)	2	3	5	1
(d)	3	1	2	4

Correct Answer: (b)

Solution:Ptyalin - It is present in saliva that catalyzes the hydrolysis of starch into maltose and dextrin.

Pepsin It is an enzyme released in stomach that degrades food proteins into peptides.

Renin- It is an enzyme that is present in kidney and converts angiotensinogen into angiotensin balancing sodium and potassium level in blood.

Oxytocin - It induces contraction of smooth muscles.

5. Antigen is a substance which : [2001]

(a) destroys harmful bacteria
(b) is used to treat poisoning
(c) lowers body temperature
(d) stimulates formation of antibody

Correct Answer: (d) stimulates formation of antibody

Solution:Antigen is a foreign molecule, which invade the body of organism, and induce immune response to stimulate antibody/generation/production.

6. Which of the following cell organelles play the most significant role in protein synthesis? [2001]

(a) Lysosome and Centrosome
(b) Endoplasmic reticulum and Ribosome
(c) Golgi apparatus and Mitochondria
(d) Lysosome and Mitochondria

Correct Answer: (b) Endoplasmic reticulum and Ribosome

Solution:Ribosome and Endoplasmic reticulum are main sites for protein synthesis. Ribosome, which serve as staging area where some RNA helps in protein synthesis. Endoplasmic reticulum is an irregular, double membrane network scattered in cytoplasm, also helps in protein synthesis.

7. The cellular and molecular control of programmed cell death is known as : [2001]

(a) apoptosis
(b) ageing
(c) degeneration
(d) necrosis

Correct Answer: (a) apoptosis

Solution:Apoptosis is the process of programmed cell death in multicellular organisms. Apoptosis occurs during normal cell turnover, development and in immune system.

Ageing is the accumulation of changes. Degeneration is the deterioration of a tissue or an organ in which its function is diminished or its structure impaired. Necrosis is the cellular death without any programming.

8. Match List-I with List-II and select the correct answer using the codes given below Match List-I with List-II and select the correct answer using the codes given below : [2001]

List-I (Bone)	List-II (Name)
A. Breast-bone	1. Clavicle
B. Collar-bone	2. Patella
C. Knee-cap	3. Scapula
D. Shoulder blade	4. Sternum

Codes:

	A	B	C	D
(a)	4	1	3	2
(b)	1	4	3	2
(c)	1	4	2	3
(d)	4	1	2	3

Correct Answer: (d)

Solution:

List-I (Bone)	List-II (Name)
A. Breast-bone	Sternum
B. Collar-bone	Clavicle
C. Knee-cap	Patella
D. Shoulder blade	It connects the humerus (upper arm bone)

with the clavicle. It is known as scapula.

9. In the context of organic evolution, the loss of limbs in snakes is explained by the phenomenon of : [2002]

(a) use and disuse of organs
(b) adaptation to living in burrows
(c) natural selection
(d) inheritance of acquired characters

Correct Answer: (a) use and disuse of organs

Solution:Tape worms are hermaphrodite (both male and female reproductive organ present). Round worms are unisexual (separate sex). Filaria is caused by Wuchereria bancrofti which is a parasitic nematode. Guinea worm is a long and very thin nematode, not an annelid.

10. In the context of organic evolution, the loss of limbs in snakes is explained by the phenomenon of : [2002]

(a) use and disuse of organs
(b) adaptation to living in burrows
(c) natural selection
(d) inheritance of acquired characters

Correct Answer: (a) use and disuse of organs

Solution:In organic evolution, Lamarck believed that any particular part of the body that is put into more frequent use, has tendency to develop stronger and better while that part of body which is put into less or no use has tendency to gradually disappear. So, loss of limbs in snake is an example of use and disuse of organs.

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Biology (Part-III) (UPSC)

1. Match List-I with List-II and select the correct answer using the codes given below: [2001]

2. Which of the following features of DNA makes it uniquely suited to store and transmit genetic information from generation to generation? [2001]

3. "Metastasis" is the process by which: [2001]

4. Match List-I with List-II and select the correct answer using the codes given below the lists : [2001]

5. Antigen is a substance which : [2001]

6. Which of the following cell organelles play the most significant role in protein synthesis? [2001]

7. The cellular and molecular control of programmed cell death is known as : [2001]

8. Match List-I with List-II and select the correct answer using the codes given below Match List-I with List-II and select the correct answer using the codes given below : [2001]

9. In the context of organic evolution, the loss of limbs in snakes is explained by the phenomenon of : [2002]

10. In the context of organic evolution, the loss of limbs in snakes is explained by the phenomenon of : [2002]

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