NCERT Class 11-Biology: Chapter – 14 Respiration in Plants Part 5 (For CBSE, ICSE, IAS, NET, NRA 2023)

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Question 10:

We commonly call ATP as the energy currency of the cell. Can you think of some other energy carriers present in a cell? Name any two.


The energy currency is the energy which is stored and released in living organisms. Adenosine Triphosphate, i.e.. , ATP acts as energy currency in plants and animals.

Some other energy carriers present in a cell are:

GTP (Guanine Triphosphate)

ADP (Adenosine Diphosphate)

Question 11:

ATP produced during glycolysis is a result of substrate level phosphorylation. Explain.


The substrate level phosphorylation occurs in the payoff phase of the glycolysis. These ATP are produced during the glycolysis of substrate level phosphorylation as these are formed without the electron transport system (ETS) and chemiosmosis. The ATP is directly formed from ADP and Inorganic phosphatase.

Question 12:

Do you know any step in the TCA cycle where there is substrate level phosphorylation? Which one?


In the TCA cycle where there is substrate level phosphorylation the step in which succinyl Co-A is converted to the succinic acid and there is one GTP molecule is synthesised through the substrate level phosphorylation.

Question 13:

In a way green plants and cyanobacteria have synthesized all the food on the earth. Comment.


a. The name of the process is cellular respiration.

b. It is a catabolic process because it involves the glucose molecule breakdown.

c. Raw materials involved in the cellular respiration process are Glucose molecule and oxygen.

Question 14:

When a substrate is being metabolized, why does not all the energy that is produced get released in one step? It is released in multiple steps. What is the advantage of step-wise release?


During cellular respiration all the energy which is contained in the respiratory substrate is not released all at once, instead it is released in a step-wise manner. The energy is released by a series of slow steps which are controlled and moderated enzymatically. It is synthesized in the chemical energy in the form of ATP. Therefore, the energy release cannot occur directly. The advantage of stepwise release of energy is that each step helps in regulation of the energy. And energy is only released when formed or when required. Energy wastage as heat is avoided and energy is stored. Thus, releasing energy in multiple steps ensures efficient use of energy by the body.

Question 15:

Respiration requires . . How did the first cells on the earth manage to survive in an atmosphere that lacked ?


The first cells on the earth managed to survive in an atmosphere that lacked because they were anaerobes, i.e.. they did not require oxygen for respiration and instead survived by the breakdown of other inorganic compounds like etc. They survived without the presence of oxygen.

Question 16:

It is known that red muscle fibres in animals can work for longer periods of time continuously. How is this possible?


Red muscle fibers in animals can work for more extended periods continuously as it has myoglobin, which is an oxygen transporting pigment. It gets bound to the oxygen molecule and stored as oxymyoglobin. During the muscle contraction, which occurs during extended periods of continuous work, the stored oxymyoglobin releases oxygen.

Question 17:

The energy yield in terms of ATP is higher in aerobic respiration than during anaerobic respiration. Explain.


Anaerobic respiration.

Efficiency is attributed to the number of ATP produced from one molecule of glucose. In Aerobic respiration produces 38 ATP molecules from a single glucose molecule while anaerobic respiration produces only 2 ATP molecules from a single glucose molecule. Therefore, aerobic respiration is more efficient than anaerobic respiration as in anaerobic respiration is because of the partial breakdown of the glucose, whereas aerobic respiration involves the complete breakdown of glucose.