What are the assumptions made during the calculation of net gain of ATP?
It is possible to make calculations of the net gain of ATP for every glucose molecule oxidised; but in reality this can remain only a theoretical exercise. These calculations can be made only on certain assumptions that:
But these kind of assumptions are not really valid in a living system; all pathway work simultaneously and do not take place one after another; substrates enter the pathways and are withdrawn from it as and when necessary; ATP is utilised as and when needed; enzymatic rates are controlled by multiple means. Hence, there can be a net gain of 36 ATP molecules during aerobic respiration of one molecule of glucose.
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 yield in terms of ATP is higher in aerobic respiration than during anaerobic respiration. Why is there anaerobic respiration even in organisms that live in aerobic condition like human beings and angiosperms?
Comment on the statement – Respiration is an energy producing process but ATP is being used in some steps of the process.
Name the site(s) of pyruvate synthesis. Also, write the chemical reaction wherein pyruvic acid dehydrogenase acts as a catalyst.
Energy is released during the oxidation of compounds in respiration. How is this energy stored and released as and when it is needed?
Mention the important series of events of aerobic respiration that occurs in the matrix of the mitochondrion as well as one that takes place in the inner membrane of the mitochondrion.
Give an account of Glycolysis. Where does it occur? What are the end products? Trace the fate of these products in both aerobic and anaerobic respiration.
Respiratory pathway is believed to be a catabolic pathway. However, nature of TCA cycle is amphibolic. Explain.
ATP produced during glycolysis is a result of substrate level phosphorylation. Explain.
The energy yield in terms of ATP is higher in aerobic respiration than during anaerobic respiration. Explain.
Match the following and choose the correct option from those given below.
| Column A | Column B | ||
| A. | Molecular oxygen | (i) | a-Ketoglutaric acid |
| B. | Electron acceptor | (ii) | Hydrogen acceptor |
| C. | Pyruvate dehydrogenase | (iii) | Cytochrome C |
| D. | Decarboxylation | (iv) | Acetyl Co A |
(a) A(ii), B(iii), C(iv), D(i)
(b) A(iii) B(iv) C(ii) D(i)
(c) A(ii)B(i)C(iii)D(iv)
(d) A(iv) B(iii) C(i) D(ii)
Respiration requires 02. How did the first cells on the earth manage to survive in an atmosphere that lacked 02?
In a way green plants and cyanobacteria have synthesised all the food on the earth. Comment.
Enumerate the assumptions that we undertake in making the respiratory balance sheet. Are these assumptions valid for a living system? Compare fermentation and aerobic respiration in this context.
In the following flow chart, replace the symbols a,b,c and d with appropriate terms. Briefly explain the process and give any two application of it.
It is known that red muscle fibres in animals can work for longer periods of time continuously. How is this possible?
The product of aerobic glycolysis in skeletal muscle and anaerobic fermentation in yeast are respectively ________ and ______.
Do you know any step in the TCA cycle where there is substrate level phosphorylation. Which one?
Oxygen is an essential requirement for aerobic respiration but it enters the respiratory process at the end? Discuss.
When a substrate is being metabolised, 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?
Explain the term "Energy Currency". Which substance acts as energy currency in plants and animals?
Respiration is an energy releasing and enzymatically controlled catabolic process which involves a step-wise oxidative breakdown of organic substances inside living cells. In this statement about respiration explain the meaning of
1. Step-wise oxidative breakdown and
2. Organic substances (used as substrates).
The figure given below shows the steps in glycolysis. Fill in the missing steps A, B, C, D and also indicate whether ATP is being used up or released at step E?
RuBP carboxylase, PEPcase, Pyruvate dehydrogenase, ATPase, cytochrome oxidase, Hexokinase, Lactate dehydrogenase. Select/choose enzymes from the list above which are involved in
a. Photosynthesis
b. Respiration
c. Both in photosynthesis and respiration
If a person is feeling dizzy, glucose or fruit juice is given immediately but not a cheese sandwich, which might have more energy. Explain.
Which of the following will release more energy on oxidation? Arrange them in ascending order?
a. 1 g of fat b. 1 g of protein
c. 1 g of glucose
d. 0.5 g of protein + 0.5 g glucose
Distinguish between the following:
(a) Aerobic respiration and Anaerobic respira ¬tion.
(b) Glycolysis and Fermentation.
(c) Glycolysis and Citric acid cycle.
Differentiate between
(a) Respiration and Combustion
(b) Glycolysis and Krebs’cycle
(c) Aerobic respiration and Fermentation