FREE NEET Biology Practice MCQ Test: Respiration In Plants Exercise 3 Questions Answers With Detailed Explanations [PDF]

Answer: (d)

Answer: (a)

Answer: (d)

Answer: (b)

Electron transport chain is a series of coenzymes and cytochromes that takes part in the passage of electrons from a chemical to its ultimate acceptor. It takes place on the cristae of mitochondria found on the inner surface of the membrane of mitochondria.

Answer: (c)

Answer: (d)

Oxidative phosphorylation is the synthesis of energy rich ATP molecules with the help of energy liberated during oxidation of reduced co-enzymes (NADH, $$FADH^2$ ) produced in respiration.

The enzyme required for this synthesis is called ATP synthase. It is located in $F_1$ or headpiece of $F_0-F_1$ or elementary particles present in the inner mitochondrial membrane. $F_1$ particle is capable of ATP synthesis. ATP synthase becomes active in ATP formation only when there is a proton gradient having higher concentration of $H^{+}$ or protons on the $F_0$ side as compared to $F_1$ side.

This higher concentration creates an electric potential across the mitochondrial membrane. The proton gradient and membrane electric potential together form proton motive force (PMF). The flow of protons through the $F_0$ channel which induces $F_1$ particle to function as ATP synthase. The energy of the proton gradient is used in attaching a phosphate radicle to ADP by high-energy bond. This produces ATP.

Answer: (c)

Answer: (c)

Answer: (b)

Glucose undergoes partial oxidation to form two molecules of pyruvic acid, Glucose is phosphorylated to give rise to glucose-6-phosphate by the activity of the enzyme hexokinase. The scheme of glycolysis was given by Gustav Embden, Otto Meyerhof, and J. Parnas, and is often referred to as the EMP pathway.

Answer: (a)

Answer: (c)

Answer: (d)

The oxygen obtained from cellular respiration combines with the hydrogen obtained from the oxidation of organic molecules to form water.

Answer: (b)

When oxygen is not available (anaerobic condition) yeast and some other microbes convert pyruvic acid into ethyl alcohol. It is a two step process. In the first step pyruvic acid is decarboxylated to yield acetaldehyde and $CO_2$ .

Pyruvic acid is a 3-C compound and acts as electron donor while acetaldehyde is the electron acceptor.

$CH_3 COCOOH →↖{pyruvic}↙{carboxylase} CH_3 CHO + CO_2$

In the  second  step acetaldehyde is  reduced to ethyl  alcohol by NADH 2 formed in the  glycolysis.

$CH_3 CHO + NADH_2 →↖{Alcoholic}↙{dehydrogenase}C_2 H_5 OH + NAD$

Answer: (c)

During glycolysis pyruvic acid is produced from glucose and is oxidatively decarboxylated to form acetyl CoA. This formation of acetyl CoA from pyruvic acid needs a multienzyme complex and 5 essential cofactors, i.e. lipoic acid, CoA, $Mg^{2+}$, NAD and TPP (thiamine pyrophosphate). It results in production of 2 molecules of $CO_2$ and 2 molecules of $NADH_2$ . This acetyl CoA enters mitochondria and is completely oxidised during Krebs' cycle. Thus acetyl CoA acts as the linker of glycolysis and Krebs' cycle.

Answer: (d)

Answer: (c)

Answer: (a)

Succinate: ubiquinone oxidoreductase, also known in mitochondria as Complex II, provides a link between the citric acid cycle and the membrane-bound electron-transport system. The membrane extrinsic, water-soluble domain, known as succinate dehydrogenase (SDH), contains the fumarate/succinate active site with a covalently bound FAD group and three iron-sulfur clusters: $[2Fe-2S]^{2} +/1+, [4Fe-4S]^{2}$+/1+, and $[3Fe-4S]^{1}$+/0. The enzyme catalyzes the interconversion of fumarate and succinate, and is closely related to fumaratereductase.

Answer: (d)

ATP molecules from ADP are generated maximum in electron transport chain.

Answer: (c)

The complete oxidation of pyruvate by the stepwise removal of all the hydrogen atoms, leaving three molecules of $CO_{2}$ . The passing on of the electrons removed as part of the hydrogen atoms to molecular $O_{2}$ with simultaneous synthesis of ATP.

Answer: (b)