Biology Questions and Answers – Plants Respiration – Fermentation


This set of Biology Multiple Choice Questions & Answers (MCQs) focuses on “Plants Respiration – Fermentation”.

1. Which of the following are the end products of the complete combustion of glucose?
a) CO2 and starch
b) Fructose and lactose
c) H2O and mannose
d) CO2 and H2O
View Answer

Answer: d
Explanation: The complete combustion of glucose, which produces CO2 and H2O as end products, yields energy most of which is given out as heat. If this energy is to be useful to the cell, it should be able to utilise it to synthesise other molecules that the cell requires.

2. What is the strategy of the plants to oxidise glucose?
a) Oxidise glucose in several large steps
b) Oxidise glucose in several small steps
c) Reduce glucose in several large steps
d) Reduce glucose in several small steps
View Answer

Answer: b
Explanation: The strategy that the plant cell uses is to catabolise the glucose molecule in such a way that not all the liberated energy goes out as heat. The key is to oxidise glucose, not in one step but several small steps.

3. During the process of respiration, which of the following is not released?
a) Carbon dioxide
b) Water
c) Oxygen
d) Energy
View Answer

Answer: c
Explanation: During the process of respiration, oxygen is utilised and carbon-dioxide, water and energy are released as products. The combustion reaction requires oxygen.
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4. What was the kind of atmosphere where the first cells on this planet lived?
a) Reducing
b) Oxidising
c) No atmosphere
d) Gold was present
View Answer

Answer: a
Explanation: The first cells on this planet lived in an atmosphere that lacked oxygen. Even among present-day living organisms, we know of several organisms that are adapted to anaerobic conditions.

5. What is the breakdown of glucose to pyruvic acid known as?
a) Respiration
b) Glycolysis
c) Combustion
d) Hydrolysis
View Answer

Answer: b
Explanation: In any case, all living organisms retain the enzymatic machinery to partially oxidise glucose without the help of oxygen. This breakdown of glucose to pyruvic acid is called glycolysis.

6. Glycolysis is also called an EMP pathway.
a) True
b) False
View Answer

Answer: a
Explanation: The scheme of glycolysis was given by Gustav Embden, Otto Meyerhof and J. Parnas and therefore is often referred to as the EMP pathway. The term glycolysis has originated from the Greek words meaning splitting of sugar.

7. Where does glycolysis take place?
a) Cytoplasm
b) Mitochondrial matrix
c) Plasma membrane
d) Inner mitochondrial membrane
View Answer

Answer: a
Explanation: Glycolysis occurs in the cytoplasm of the cell and is present in all the living organisms. In anaerobic organisms, it is the only process in respiration.

8. Who discovered fermentation?
a) Gay Lussac
b) Louis Pasteur
c) Kepler
d) Ernst Haeckel
View Answer

Answer: b
Explanation: Fermentation was discovered by Louis Pasteur. It is incomplete oxidation of glucose which is achieved under anaerobic conditions. It takes place in many prokaryotes and unicellular eukaryotes.

9. What are the final products of fermentation?
a) CO2 and H2O
b) CO2 and methanol
c) H2O and ethanol
d) CO2 and ethanol
View Answer

Answer: d
Explanation: In the process of fermentation, say by yeast, the incomplete oxidation of glucose is achieved under anaerobic conditions by sets of reactions where pyruvic acid is converted to CO2 and ethanol.

10. Which of the following enzymes is not used under anaerobic conditions?
a) Pyruvic decarboxylase
b) Alcohol dehydrogenase
c) Lactate dehydrogenase
d) Pyruvate dehydrogenase
View Answer

Answer: d
Explanation: The enzymes like pyruvic decarboxylase and alcohol dehydrogenase catalyse the steps of alcoholic fermentation. Lactate dehydrogenase is used for lactic acid fermentation.

11. Where does lactic acid fermentation take place in animal cells?
a) In the whole body
b) Sometimes in the muscles
c) Main respiratory pathway for muscles
d) In eyes
View Answer

Answer: b
Explanation: In animal cells, lactic acid fermentation takes place in the muscles during the exercise, when oxygen is inadequate for cellular respiration, pyruvic acid is reduced to lactic acid by lactate dehydrogenase.

12. In lactic acid fermentation, the reducing agents are carbon dioxide and water.
a) True
b) False
View Answer

Answer: b
Explanation: In lactic acid fermentation as well as alcoholic fermentation, the reducing agent is NADH+H+ which is re-oxidised to NAD+. Both these processes are hazardous, as either acid or alcohol is produced.

13. How much energy is released in lactic acid and alcohol fermentation?
a) Less than 7 per cent
b) More than 7 per cent
c) More than 50 per cent
d) More than 75 per cent
View Answer

Answer: a
Explanation: In both lactic acid and alcohol fermentation not much energy is released; less than 7 per cent of the energy in glucose is released and not all of it is trapped as high energy bonds of ATP.

14. At what percentage, yeast poison themselves?
a) 4%
b) 7%
c) 13%
d) 45%
View Answer

Answer: c
Explanation: Yeast poison to death when the concentration of alcohol reaches about 13 per cent. Therefore, the maximum concentration of alcohol in beverages which are naturally fermented is 13 per cent.

15. In how many ways do different cells handle pyruvic acid?
a) One
b) Two
c) Three
d) Four
View Answer

Answer: c
Explanation: There are three major ways in which different cells handle pyruvic acid produced by glycolysis:
i. Lactic acid fermentation
ii. Alcoholic fermentation
iii. Aerobic Respiration

Sanfoundry Global Education & Learning Series – Biology – Class 11.

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