Respiration in Plants Test - 32

The one turn of the citric acid cycle releases two carbon dioxide molecules and produces three NADH, one FADH2, and one ATP or GTP. As the cycle turns twice so the number of CO$$_2$$ molecule produce will be 2X2=4 molecules.

Solution

Correct answer is option C.
Explanation for correct option

• Glycolysis (from glycose, an older term for glucose + -lysis degradation) is the metabolic pathway that converts glucose $$C_6H_{12}O_6$$, into pyruvate, $$CH_3COCOO$$ + $$H^+$$.
• In glycolysis, during oxidation electrons are removed by $$NAD^+$$ which den converted into $$NADH_2$$.
• Oxidation of glyceraldehyde 3-phosphate into 1,3-bis phosphoglycerate leads to the production of 2 $$NADH_2$$ molecules. Thus, option C is correct. 
• ATP, glyceraldehyde 3-phosphate and molecular oxygen are not involved in the removal of electrons during glycolysis. Thus, other options are incorrect.

Glycolysis is an oxidoreductive process that occurs in cytosol of all living cells (prokaryotes and eukaryotes). Common in both aerobic and anaerobic respiration. Respiratory substrates are reduced to form Pyruvic Acid with the production of ATP and NADH$$_{2}$$. Conversion of NAD to NADH$$_{2}$$ is an oxidative process in glycolysis. Here substrate gets reduced and NAD will be oxidised. So, glycolysis is called as oxido reductive reactions or redox reactions. Thus, option D is correct.

The respiratory quotient (R.Q) is the ratio of $$CO_2$$ produced to $$O_2$$ consumed, while food is being metabolized.
RQ = $$CO_2$$ eliminated / $$O_2$$ consumed
In the above reaction, 102 $$CO_2$$ molecules are produced and 146 $$O_2$$ molecules are consumed. Therefore,
RQ = 102 / 146 = 0.7
Thus, option A is correct and other options are incorrect.

Solution

Correct answer is option B.

Explanation for correct option

• The respiratory quotient (RQ) is the ratio of $$CO_2$$ produced to $$O_2$$ consumed while food is being metabolized.
• RQ = $$CO_2$$ eliminated/$$O_2$$ consumed
• R.Q for carbohydrates is 1, for proteins is about 0.8, for fatty acids is about 0.7 and for organic acids is more than 1.
• So, the respiratory quotient during cellular respiration would depend on the nature of the substrate. Thus, option B is correct.

The respiratory quotient (RQ) is the ratio of CO$$_2$$ produced to O$$_2$$ consumed, while food is being metabolized. The carbohydrates have equal numbers of carbon and oxygen in their molecules. When carbohydrates are used as the substrate, then the RQ will be 1, because equal amounts of carbon dioxide and oxygen are evolved and consumed. So, the correct answer is option A.

Glycolysis is the metabolic pathway that converts glucose into pyruvate. During glycolysis process, 2 ATP molecules and 2 NADH molecules are produced. FADH is not produced during glycolysis. Thus, option D is correct and other options are incorrect.

Glycolysis takes place in the cytoplasm of the cell and is common to both aerobic and anaerobic respirations. In this step, glucose (6C) is broken in
a stepwise manner into two molecules of pyruvic acid, without utilizing oxygen. 

Fermentation is incomplete oxidation of food substances into alcohol or lactic acid with $$CO_2$$ gas and a small amount of energy being released. Both lactic acid and ethanol fermentation do not produce oxygen. Hence, fermentation in a closed vessel will develop higher gas pressure due to excessive $$CO_2$$. 

Potato tubers are rich in starch, which is a carbohydrate. The R.Q of carbohydrates is 1, because, amount of $$CO_2$$ evolved is equal to the amount of $$O_2$$ consumed. Thus, option C is correct and other options are incorrect.