Test: Respiration in Plants - Gycolysis (July 4) - NEET MCQ

Respiration is a catabolic process, which oxidises reduced substrates, thus, resulting in the energy stored in reduced substrates. The reduced substrates are produced by the process of photosynthesis occurring in green plants and the reduced substrates are oxidised through respiration releasing CO₂, water vapour and energy in the form of ATP.
So, the correct answer is 'It liberates CO₂'

Answer:
The energy obtained by a cell from catabolic reactions is stored immediately in the form of ATP (adenosine triphosphate). Here is a detailed explanation of why ATP is the correct answer:
ATP (Adenosine Triphosphate)
- ATP is a molecule that stores and releases energy within cells. It is often referred to as the "energy currency" of the cell.
- ATP consists of adenosine and three phosphate groups. The energy is stored in the high-energy phosphate bonds between the phosphate groups.
- When ATP is hydrolyzed, meaning one of the phosphate groups is removed, it releases energy that can be used by the cell for various metabolic processes.
- Catabolic reactions, such as cellular respiration, break down molecules like glucose to produce ATP.
- This ATP can then be used by the cell for activities like cellular work, active transport, and synthesis of macromolecules.
In summary, ATP is the immediate form in which energy obtained from catabolic reactions is stored in cells.

Source of Respiration: Stored Food
Respiration is the process by which living organisms obtain energy from the food they consume. In the case of humans and many other organisms, the source of respiration is stored food.
Explanation:
- Respiration is a metabolic process that occurs in all living cells.
- It involves the breakdown of organic molecules, such as carbohydrates, fats, and proteins, to release energy.
- This energy is stored in the form of adenosine triphosphate (ATP), which is the primary energy currency of cells.
- The process of respiration occurs in multiple steps, including glycolysis, the Krebs cycle, and oxidative phosphorylation.
- In each step, stored food molecules are broken down and converted into ATP.
- The main source of stored food used for respiration is glucose, a type of carbohydrate.
- Glucose is obtained from food sources such as carbohydrates (bread, rice, fruits, etc.) and is stored in the body as glycogen in the liver and muscles.
- During respiration, glycogen is broken down into glucose, which is further metabolized to release ATP.
- Other stored food molecules, such as fats and proteins, can also be used as alternative sources of energy during respiration.
Therefore, the correct answer is A: Stored food is the source of respiration.

Respiratory quotient is defined as the ratio of carbon dioxide eliminated to that of oxygen consumed. Dark succulents undergo incomplete oxidation. When incomplete oxidation takes place, the value of R.Q. is zero. It is because during incomplete oxidation no carbon dioxide is released. Thus, the correct answer is option D.

Explanation:
Aerobic respiration of glucose is a process that occurs in the presence of oxygen and results in the breakdown of glucose molecules to release energy. This process takes place in the mitochondria of cells and involves several enzymatic reactions.
The overall equation for aerobic respiration is:
Glucose + Oxygen → Carbon dioxide + Water + Energy
The energy released during aerobic respiration is measured in kilocalories (K.cal) and can be calculated using the following equation:
Energy released = Number of glucose molecules x 686 K.cal
Now, let's calculate the energy released during aerobic respiration of glucose:
Given: Aerobic respiration of glucose
To calculate the energy released, we need to know the number of glucose molecules involved in the process. Let's assume we have 1 mole of glucose (C6H12O6) for simplicity.
1 mole of glucose = 6 moles of carbon dioxide + 6 moles of water
From the balanced equation, we can see that the number of moles of carbon dioxide and water produced is equal to the number of moles of glucose consumed.
1 mole of glucose = 6 moles of carbon dioxide + 6 moles of water
Now, let's calculate the energy released:
Energy released = Number of moles of glucose x 686 K.cal
Since we assumed 1 mole of glucose, the energy released would be:
Energy released = 1 x 686 K.cal = 686 K.cal
Therefore, the correct answer is option C: 686 K.cal.

Chemiosmotic Theory of P. Mitchell (1978) and ATP Synthesis

The chemiosmotic theory, proposed by Peter Mitchell in 1978, explains how ATP (adenosine triphosphate) is synthesized on membranes. According to this theory, ATP synthesis occurs due to a proton gradient across the membrane. Let's explore this concept in more detail:

1. Chemiosmotic Theory:

• The chemiosmotic theory describes the generation of ATP through the movement of protons (H+) across a membrane.


• It suggests that the energy released during electron transport in the electron transport chain is used to pump protons across the membrane, creating a proton gradient.


• This proton gradient is established by the movement of electrons through membrane-bound protein complexes, such as the respiratory chain in mitochondria or the photosynthetic chain in chloroplasts.

2. ATP Synthesis:

• The proton gradient created by the chemiosmotic process provides the necessary energy for ATP synthesis.


• ATP synthase, an enzyme complex located in the membrane, utilizes the energy of the proton gradient to drive the synthesis of ATP.


• As protons flow back across the membrane through ATP synthase, the enzyme uses this energy to convert ADP (adenosine diphosphate) and inorganic phosphate (Pi) into ATP.


• This process is known as oxidative phosphorylation in mitochondria or photophosphorylation in chloroplasts.

3. Significance of the Proton Gradient:

• The proton gradient plays a crucial role in ATP synthesis as it provides the energy needed to drive the production of ATP.


• By coupling the movement of protons with ATP synthesis, the chemiosmotic theory explains how cells efficiently generate ATP, which is the primary energy currency of the cell.


• It also highlights the importance of membrane structures, such as the inner mitochondrial membrane or thylakoid membrane, in creating and maintaining the proton gradient.

In conclusion, according to the chemiosmotic theory proposed by Peter Mitchell, ATP synthesis on membranes occurs due to a proton gradient. This theory revolutionized our understanding of cellular energy production and provided a mechanistic explanation for ATP synthesis in various cellular processes.

Breakdown of carbohydrates (glucose) takes place in the body by glycolysis followed by tricarboxylic acid cycle (Kreb's cycle) resulting in the energy in the form of ATP. Glucose can alternatively also undergo a different pathway to produce other products required by the cells. One of these alternate pathways is the pentose phosphate pathway or also called as hexose monophosphate pathway in which oxidation of glucose 6-phosphate takes place to produce pentoses. The fate of glucose whether to undergo glycolysis or the hexose monophosphate pathway is decided by the relative concentrations of NADP+ and NADPH. The phase starts with the oxidation of glucose 6-phosphate by the enzyme glucose 6-phosphate dehydrogenase to yield 6-phosphogluconolactone. This enzyme is an NADP dependent enzyme, where NADP+accepts an electron to form NADPH + H+.

Inhibitors, resemble with substrate molecules, join in the active site of the enzyme and inhibit the enzyme activity are called Competitive enzyme inhibitors.

Malonate is a competitive inhibitor of succinic dehydrogenase. The binding of succinic dehydrogenase to the substrate, succinate, is completely inhibited. Succinic dehydrogenase catalyzes the oxidation of succinate to fumarate in the Kreb cycle was an experiment demonstrated as an example of competitive inhibition.

So, the correct option is, 'succinic dehydrogenase by malonic acid'.

Hexose monophosphate shunt is a secondary pathway for the metabolism of glucose in tissues other than skeletal muscles, in which five-carbon sugars are synthesized and NADPH is produced with the loss of CO₂ in the cytoplasm outside the mitochondria, whereas there is no CO₂ production in glycolysis.

The formation of Acetyl Co-A from pyruvic acid is the result of its
Oxidative decarboxylation:
- Pyruvic acid, a product of glycolysis, enters the mitochondria for further metabolism.
- In the mitochondria, pyruvic acid undergoes oxidative decarboxylation to form Acetyl Co-A.
- This process involves the removal of a carboxyl group from pyruvic acid, resulting in the release of carbon dioxide as a waste product.
- The remaining two carbon fragment combines with Coenzyme A (Co-A) to form Acetyl Co-A.
Key points:
- Acetyl Co-A serves as an important intermediate in various metabolic pathways, including the citric acid cycle (Krebs cycle) and fatty acid synthesis.
- The conversion of pyruvic acid to Acetyl Co-A is a crucial step in aerobic respiration, as it connects glycolysis to the citric acid cycle.
- This process occurs in the presence of the enzyme pyruvate dehydrogenase, which catalyzes the oxidative decarboxylation reaction.
- The formation of Acetyl Co-A generates high-energy electrons, which are later used in the production of ATP through oxidative phosphorylation.
- Acetyl Co-A is an important molecule that links carbohydrate, lipid, and protein metabolism, making it a central player in cellular energy production.