Respiration in plants MCQ: Introduction and Explanation

Answer: a. Tissue respiration

Explanation. Metabolic water is the water produced by a live organism's metabolism as a result of the oxidation of energy-containing compounds in their meal.

Water is produced as a by-product of the oxidation of glucose and free fatty acids during cellular respiration. Additionally, as glycogen is oxidized, the H2O molecule that is chemically bonded to it is released.

Answer: d. Magnesium

Explanation. Photosynthesis takes place in chlorophyll, a green pigment found in plants. Magnesium is the central atom of a chlorophyll molecule and each molecule contains 6.7 percent magnesium. Magnesium is the required element for the activation of enzymes involved in respiration, photosynthesis, and the production of nucleic acids.

Answer: d. Cytoplasm

Explanation. Glycolysis is a two-stage process that breaks down glucose, a 6-carbon molecule, in the cytoplasm. Through a sequence of events, glucose is broken down into two phosphorylated 3-carbon molecules in the first step. Each of the 3-carbon compounds is oxidized in the second step, yielding pyruvate and net two molecules of ATP.

Answer: b C-C bonds

Explanation: When the C-C bonds of complex molecules are broken by oxidation within the cells, a significant quantity of energy is released. Sugars and fatty acids are transformed into carbon dioxide to obtain energy. As a result, the C-C bonds must be broken. C-C bonds, on the other hand, must be formed during photosynthesis. Electrons from broken bonds move to atoms where new bonds are formed in all processes.

Answer: d. DNA 

Explanation. Nucleic acids like DNA and RNA are never oxidized to release energy since they are integral elements of the cell and are utilized to carry or express many genes in humans that perform activities such as protein, fat, and carbohydrate production.

Answer: b. Mitochondria 

Explanation. Aerobic respiration is a process in which oxygen is used in the catabolism of foods, mostly carbohydrates, to create carbon dioxide and water, with the electrons produced going through an electron transport chain. The electron acceptor in this case is oxygen. The ATP molecules generated as a result of this process are used to generate energy. Mitochondria are the organelles that carry out aerobic respiration. Glycolysis, Kreb's cycle, and the electron transport chain are the processes of aerobic respiration that take place. Except for red blood cells, it is a membrane-bound organelle found in all cells. ETC and Krebs cycle take place in the mitochondrial matrix.

Also Read: Aerobic and Anaerobic Respiration

Answer: a. Two molecules of NADH are produced by one molecule of pyruvate

Explanation.  Within the mitochondria, aerobic respiration occurs, and pyruvate is transferred from the cytoplasm to the mitochondria. When pyruvate reaches the mitochondrial matrix, it undergoes a long chain of events catalyzed by pyruvate dehydrogenase, which results in oxidative decarboxylation. Several coenzymes, including NAD+ and coenzyme, are required for the processes catalyzed by pyruvate dehydrogenase.

Two molecules of NADH are created due to the metabolism of two molecules of acid, resulting in a net gain of six ATP molecules. (6 ATP = 2 NADH)

The acetyl CoA then enters a cyclic route known as the tricarboxylic acid cycle or Krebs' cycle. The Krebs cycle begins with the acetyl molecule of acetyl-CoA reacting with the four-carbon dicarboxylic acid oxaloacetate, to generate citrate, a six-carbon triad xylic acid. The enzyme citrate synthase catalyzes this process, which results in the release of a molecule of CoA.

Answer: b. 6 

Explanation. Citric acid has six carbon atoms.

Acetyl CoA is a two-carbon molecule that reacts with oxaloacetate, a four-carbon molecule, to generate citric acid/citrate, which is a six-carbon molecule. The citric acid cycle is a multi-step process in which citrate is produced in the first phase. It is a colourless and odourless weak organic acid. 

Citric acid is present in the mitochondria of the cell. Many biological fluids, including urine, saliva, cerebrospinal fluid, and breast milk, contain it. Citric acid is present in a variety of foods, including oranges, lemons, raspberries, poppy opium, bamboo shoots, and many more. This means it can function as a biomarker in our bodies for certain foods. The presence of citric acid might also indicate the existence of certain illnesses and conditions, such as rhabdomyolysis, seizures, and mental retardation, among others.

Answer: c. Glycolysis, Krebs cycle, and terminal oxidation

Explanation. Aerobic respiration is a biological mechanism in which living cells create energy from glucose in the form of ATP. 

Glucose (C6H12O6) + oxygen 6 (O2) carbon dioxide 6 (CO2) + water 6 (H2O) + energy (ATP)

There are four phases of aerobic respiration:

1. Glycolysis is the first anaerobic phase of respiration, as it does not require oxygen and generates two molecules of pyruvate from one molecule of glucose. 

2. Acetyl Coenzyme A Formation- Pyruvate is transformed to a two-carbon acetyl group, which is subsequently combined with coenzyme A to generate Acetyl Coenzyme A.

3. Krebs cycle- In this stage, acetyl coenzyme A interacts with oxaloacetate to form citrate in the mitochondria. To resume the cycle, the citrate goes through multiple conversion stages before becoming oxaloacetate. To break down acetyl coenzyme A from a single glucose molecule and create 2 ATP, 6 NADH, and 2 FADH, it takes two revolutions of the citric acid cycle.

4. The electron transport chain is the final stage in the production of significant quantities of ATP, in which NADH and FADH give their electrons. The total amount of ATP produced by one molecule of glucose is 34. 

Also read Difference between Photosynthesis and Respiration

Answer: a. Three 

Explanation. CO₂ is emitted in three separate phases of pyruvic acid aerobic respiration. These are the steps:

• During the synthesis of acetyl Co-A.
• During the Krebs cycle, alpha-ketoglutaric acid is formed.
• During the Krebs cycle, succinic acid is formed.