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GATE Life Sciences

Description: GATE
Number of Questions: 15
Created by:
Tags: GATE Photosynthesis The Respiratory System The Excretory System Hyper sensitivity Organelles
Attempted 0/15 Correct 0 Score 0

Assertion: Leukocytes make up approximately fifteen percent of the total blood volume in a healthy man. Reason: An increase in the number of leukocytes over the upper limits is called leukopenia.

Directions: In the following question there are two statements, Assertion (A) and Reason (R), consider both the statements independently and mark your answers as under:

1. If A and R both are correct and R is correct explanation of A.
2. If A and R both are correct and R is not correct explanation of A.
3. If A is correct and R is incorrect.
4. If A is incorrect and R is correct.
5. If A and R both are incorrect.

  1. A and R both are correct and R is the correct explanation of A.

  2. A and R both are correct and R is not the correct explanation of A.

  3. A is correct and R is incorrect.

  4. A is incorrect and R is correct.

  5. A and R both are incorrect.


Correct Option: E
Explanation:

Both A and R are incorrect. Leukocytes make up approximately 1% of the total blood volume in a healthy man. An increase in the number of leukocytes over the upper limits is called leukocytosis, and a decrease below the lower limit is called leukopenia.

Which of the following statements is/are correct about C3 carbon fixation?

  1. C3 carbon fixation occurs only in tropical zone climates.
  2. Leaves show Kranz anatomy.
  3. Mesophyll cells are not differentiated.
  4. Bundle sheath is absent.
  1. 1 and 2

  2. 1, 2 and 3

  3. 2, 3 and 4

  4. Only 3

  5. Only 4


Correct Option: E
Explanation:

Bundel sheath is not found in C3 plants. Thus, this option is correct.

Which of the following matches of ‘reaction of the C3 carbon fixation: enzyme catalysing that step’ is not correct?

  1. Carboxylation of ribulose-1,5-bisphosphate : RuBisCO

  2. Gluconeogenesis : Phosphoglycerate kinase

  3. Spliting of fructose 1,6-bisphosphate : Aldolase

  4. Hexose monophosphate shunt : Ribose-5-phosphate isomerase

  5. Pentose phosphate pathway : Phosphoribulokinase


Correct Option: D
Explanation:

In hexose monophosphate shunt, Xylulose 5-phosphate converts into ribulose 5-phosphate, is catalysed by ribulose-phosphate epimerase. Conversion of ribose 5-phosphate to Ribulose 5-phosphate is catalysed by ribose-5-phosphate.

Which of the following herbicides act by interfering in light reaction of photosynthesis?

  1. 2,4-Dichlorophenoxyacetic acid
  2. 3-(3,4-Dichlorophenyl)-1,1-dimethylurea
  3. N-(phosphonomethyl)glycine
  4. 1-Chloro-3-ethylamino-5-isopropylamino-2,4,6-triazine
  1. 1 and 2

  2. 1 and 3

  3. 1 and 4

  4. 2 and 3

  5. 2 and 4


Correct Option: E
Explanation:

Two major classes of herbicides that block photosynthetic electron flow are derivatives of urea and triazine herbicides. These herbicides interfere in PS II with binding of plastoquinone (Q) and thus, blocks the transfer of electrons to plastoquinone and also blocks electron transport between PS II and PS I. Examples: Urea derivatives: 3-(4-chlorophenyl)-1-methoxy-1-methylurea and 3-(3,4-Dichlorophenyl)-1,1-dimethylurea Triazine derivatives: 6-Chloro-N,N'-diethyl-1,3,5-triazine-2,4-diamine and 1-Chloro-3-ethylamino-5-isopropylamino-2,4,6-triazine.

Which of the following plants is an example of crassulacean acid metabolism?

  1. Money tree

  2. Maize plant

  3. Sugarcane

  4. Barley

  5. Asian rice


Correct Option: A
Explanation:

Money tree (Crassula ovata) is an example of CAM plants. CAM is named after the family Crassulaceae, CAM stands for crassulacean acid metabolism because it was first studied in members of the plant family Crassulaceae, to which Jade plant (Crassula ovata) belongs.

Which of the following statements are correct regarding Photosystem I.

  1. Photosystem I occurs in outer surface of thylakoids.
  2. Reaction centre of Photosystem is P680.
  3. It participates in both cyclic as well as noncyclic photophosphorylation.
  4. Molecular oxygen is evolved as a result of photodissociation of water.
  1. 1 and 2

  2. 1 and 3

  3. 1 and 4

  4. 2 and 3

  5. 2 and 4


Correct Option: B
Explanation:

PS I lies in the outer surface of thylakoids. PS I participates in both cyclic as well as noncyclic photophosphorylation.

Which among the following statements about photosynthesis are correct?

  1. Best photosynthesis takes place in violet light.
  2. Quantum yield of photosynthesis is 0.125.
  3. Energy conversion efficiency of photosynthesis is 66%.
  4. 90% of the total photosynthesis in the world is carried out by marine algae.
  1. 1 and 2

  2. 1 and 3

  3. 1 and 4

  4. 2 and 3

  5. 2 and 4


Correct Option: E
Explanation:

Quantum yield of photosynthesis is 0.125. 90% of the total photosynthesis in the world is carried out by marine algae.

Which of the following is a copper-containing protein involved in electron-transfer?

  1. Plastoquinone

  2. Plastocyanin

  3. Phycocyanin

  4. Pheophytin

  5. Ferredoxin


Correct Option: B
Explanation:

Plastocyanin is a copper-containing protein that plays a role in the electron transport process associated with photosynthesis.

Which of the following statements are not correct about noncyclic photophosphorylation?

  1. Oxygenic process.
  2. Only one light trapping system (Photosystem I) is involved.
  3. NADPH is not synthesised.
  4. NADP acts as last electron acceptor.
  1. 1 and 2

  2. 1 and 3

  3. 2 and 3

  4. 2 and 4

  5. 3 and 4


Correct Option: C
Explanation:

Two light trapping systems (PS I and PS II) are involved in noncyclic photophosphorylation. NADPH is synthesised during noncyclic photophosphorylation.

Which of the following statements are not true about C4 carbon fixation?

P. CO2 fixation occurs twice. Q. Phosphoenolpyruvate acts as CO2 acceptor in bundle sheath. R. Leaf anatomy is of Kranz type. S. Requires 18 ATP for synthesis of one molecule of glucose.

  1. 1 and 2

  2. 1 and 3

  3. 2 and 3

  4. 2 and 4

  5. 3 and 4


Correct Option: D
Explanation:

Phosphoenolpyruvate  (PEP) in mesophyll cells and Ribulose-1,5-bisphosphate (RuBP) in bundle sheath functions as carbon dioxide acceptors. C4 plants require 30 ATP for synthesis of one molecule of glucose.

Which of the following diseases are caused due to hypersecretion of adrenal cortex hormones?

  1. Adrenal virilism
  2. Addison’s disease
  3. Ateliosis
  4. Conn’s syndrome
  5. Cretinism
  1. 1 and 2

  2. 1 and 4

  3. 2 and 3

  4. 3 and 4

  5. 4 and 5


Correct Option: B
Explanation:

Adrenal virilism is the development of male secondary sex characteristics caused by male sex hormones called androgens, excessively produced by the adrenal gland. Conn's syndrome is a disease of the adrenal glands involving excess production of a hormone, called aldosterone.

Which of the following photosynthetic pigments are not found in tracheophytes and charophyta?

  1. Chlorophyll a
  2. Chlorophyll b
  3. Chlorophyll c
  4. Phycobilins
  1. 1 and 2

  2. 2 and 3

  3. 2 and 4

  4. 3 and 4

  5. 2, 3 and 4


Correct Option: D
Explanation:

Chlorophyll c is found only in the photosynthetic members of the Chromista as well as the dinoflagellates. Phycobilins are water-soluble pigments and are therefore, found in the cytoplasm or in the stroma of the chloroplast. They occur only in Cyanobacteria and Rhodophyta.

The correct sequence for flow of electrons from excited P680* (in PS II) to P700 (reaction centre of PS I) is ________________.

  1. P680* → Pheophytin → Plastoquinone → Cytochrome b6-f complex → Plastocyanin → P 700

  2. P680* → Pheophytin → Cytochrome b6-f complex → Plastoquinone → Plastocyanin → P 700

  3. P680* → Plastocyanin → Plastoquinone → Cytochrome b6-f complex → Pheophytin → P 700

  4. P680* → Plastoquinone → Pheophytin → Plastocyanin → Cytochrome b6-f complex → P 700

  5. P680* → Plastoquinone → Pheophytin → Cytochrome b6-f complex → Plastocyanin → P 700


Correct Option: A
Explanation:

The correct sequence for flow of electrons from excited P680* (in PS I) to P700 (reaction centre of PS II) is P680* → Pheophytin → Plastoquinone → Cytochrome b6-f complex → Plastocyanin → P 700. The excited form of P680, designated as P680*, is rapidly photo oxidized as it passes an electron to pheophytin, which is the primary electron acceptor of PS II. Reduced pheophytin, then hands on the electron to reduce plastoquinone. From reduced plastoquinone, electrons are accepted by cytochrom b6-f complex which gets reduced in this process. From reduced Cytochrome, b6-f complex electrons are taken up by plastocyanin, which is thus reduced. From reduced plastocyanin, electrons are accepted by P700, reaction centre of PS I, which is thus reduced.

Assertion: In capping, methyl guanosine triphosphate is added to the 3'-end of hnRNA. Reason: In tailing, adenylate residues are added at 5'-end in a template independent manner.

Directions: In the following question there are two statements, Assertion (A) and Reason (R), consider both the statements independently and mark your answers as under:

1. A and R both are correct and R is correct explanation of A.
2. A and R both are correct and R is not correct explanation of A.
3. A is correct and R is incorrect.
4. A is incorrect and R is correct.
5. A and R both are incorrect.

  1. Both A and R are correct and R is the correct explanation of A.

  2. A and R both are correct and R is not the correct explanation of A.

  3. A is correct and R is incorrect.

  4. A is incorrect and R is correct.

  5. Both A and R are incorrect.


Correct Option: E
Explanation:

Both are incorrect statements. In capping, methyl guanosine triphosphate is added to the 5'-end of hnRNA. In tailing, adenylate residues are added at 3'-end in a template independent manner. It is the fully processed hnRNA, now called mRNA, that is transported out of the nucleus for translation.

Match the column – I with column – II and select the correct option.

Column – I Column – II
A. DDBJ 1. Bibliographic database
B. MEDLINE 2. Nucleotide sequence database
C. NatureServe 3. Model organism database
D. WormBase 4. Biodiversity database
  1. A - 4, B - 3, C - 2, D - 1

  2. A - 2, B - 1, C - 4, D - 3

  3. A - 2, B - 1, C - 3, D - 4

  4. A - 3, B - 2, C - 4, D – 1

  5. A - 1, B - 2, C - 3, D – 4


Correct Option: C
Explanation:

DNA Data Bank of Japan (DDBJ) is a nucleotide sequence database. It is a biological database that collects DNA sequences. MEDLINE is a bibliographic database of life sciences and biomedical information which provides bibliographic information for articles from academic journals covering medicine, nursing, pharmacy, dentistry, veterinary medicine, and health care. NatureServe is a sophisticated biodiversity database which acts as an authoritative source for information on more thant 70,000 plants, animals, and ecosystems of the United States and Canada. WormBase is an online biological database about the biology and genome of the model organism Caenorhabditis elegans (a nematode) and contains information about other related nematodes.

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