Test: Respiration & Enzymes - 2 - ACT MCQ

Glycolysis is an anaerobic process and involves the degradation of one molecule of glucose into two molecules of pyruvic acid, with generation of two molecules of ATP.

An electron transport chain is a series of compounds that transfer electrons from electron donors to electron acceptors via redox reactions and couples this electron transfer with the transfer of protons across a membrane. This creates an electrochemical proton gradient that drives ATP synthesis. Cytochrome a3 is terminal cytochrome of ETC. It has Fe+++ and Cu++ both. With Fe+++, it picks up electrons and through Cu++ it passes electrons to oxygen.

Two molecules of pyruvate are formed from the breakdown of glucose at the end of glycolysis. The pyruvate is then converted to acetyl CoA which is further oxidized in the mitochondria. Acetyl CoA enters Krebs cycle and is oxidized to CO₂, H₂O, ATP, FADH₂ and NADH⁺. This complete oxidation of pyruvate requires 10 molecules of oxygen.
So, the correct answer is '10'

The Krebs cycle occurs in the mitochondrial matrix and as the first stable product of Krebs cycle is citric acid, it is also called as the citric acid cycle.

Because plants are a living thing. The characteristics of a plant cell is similar to all living organisms on the basics of respiration.

In all living organisms including plants energy is released by the process of respiration. Respiration is chemically an oxidative process in which reduced substrates (carbohydrates, fats and amino acids) are oxidised and energy is released. All oxidative steps in the degradation of carbohydrates, fats and amino acids converge at the final stage of cellular respiration, in which the energy of oxidation drives the synthesis of ATP.

NADH is yielded in three steps -
(a) oxidation of isocitrate to oxalosuccinate
(b) oxidation of α-ketogluterate to succinyl CoA
(c) oxidation of malate to oxaloacetate.
Thus, 3 NADH molecules are formed and CO₂ is produced during conversion of oxalosuccinate to α-ketogluterate and the latter to succinyl CoA. So, in 1 cycle 3 NADH and 2 CO₂ are formed.

Oxaloacetic acid is the first member of the TCA cycle. The continued oxidation of acetyl CoA via the TCA cycle requires the continued replenishment of Oxaloacetic acid.

Mitochondria play host to one of the most important processes in your body: cellular respiration. Taking in glucose and oxygen, mitochondria produce energy, which they capture and package as energy-rich molecules of ATP.

Oxygen, for plants, is essential because it makes the process of respiration more efficient (known as aerobic respiration). Plant cells are respiring constantly. When leaves are illuminated, plants generate their own oxygen.

Plants, like all other living organisms, carry out mitochondrial respiration, the oxidation of substrates to CO₂ and the conversion of O₂ to H₂O with the concomitant release of energy. Oxygen is consumed because respiration is essentially an oxidation process in which reduced substrates (produced in photosynthesis) are oxidised.

Anaerobic respiration involves the incomplete breakdown of glucose. It releases around 5% of the energy released by aerobic respiration, per molecule of glucose. In yeast it can be observed, as alcoholic fermentation. A biological process in which molecules such as glucose, fructose, and sucrose are converted into cellular energy and thereby produce ethanol and carbon dioxide as metabolic waste products.

Respiration is an enzyme control process of oxidation of food material that consumes oxygen and as a result, it produces carbon dioxide and water and releases energy. The energy released is stored in the form of ATP. It is a catabolic process.
So, the correct option is 'Respiration'.

The production of GTP (guanosine triphosphate) occurs in the citric acid cycle during the conversion of succinyl CoA to succinate. In this step, succinyl CoA is converted into succinate through the enzymatic action of succinyl-CoA synthetase. During this conversion, a high-energy phosphate group is transferred from succinyl CoA to GDP (guanosine diphosphate), resulting in the production of GTP. GTP can later be used to generate ATP through the action of nucleoside diphosphate kinase.

A number cellular respiration enzymes are controlled by the binding of regulatory molecules at one or more allosteric sites. (An allosteric site is just a regulatory site other than the active site.) Binding of a regulator to the allosteric site of an enzyme changes its structure, making it more or less active.

Adenosine triphosphate (ATP) is a nucleotide with three phosphates. It is the universal energy currency for all cellular metabolic processes. Endergonic processes are driven by energy input using hydrolysis of ATP. Exergonic processes are coupled to ATP synthesis. The process of ATP synthesis is called phosphorylation because ATP is synthesized by phosphorylation of adenosine diphosphate (ADP) or adenosine monophosphate (AMP). The energy obtained by a cell from catabolic reactions is stored immediately in the form of ATP, as it is the energy currency of the cell.

ATP is often called a high energy compound and its phosphoanhydride bonds are referred to as high-energy bonds. There is nothing special about the bonds themselves. They are high-energy bonds in the sense that free energy is released when they are hydrolyzed, for the reasons given above.

Respiration is the catabolic process, which releases energy stored in reduced substrates and also results in the synthesis of important biochemical intermediates. Respiration can be aerobic when it occurs in presence of oxygen or anaerobic when it occurs in absence of oxygen. Aerobic respiration releases considerably more energy and results in complete oxidation of reduced substrates. Anaerobic respiration is an incomplete oxidation process. during germination seed respire in the absence of oxygen.

The oxidation process of glycolysis that involves the production of NADH is the conversion of triose-phosphate to triose-bisphosphate. During this step, the enzyme glyceraldehyde-3-phosphate dehydrogenase catalyses the oxidation of glyceraldehyde-3-phosphate (a triose-phosphate) to 1,3-bisphosphoglycerate (a triose-bisphosphate). In this process, NAD⁺ (nicotinamide adenine dinucleotide) is reduced to NADH₂.

Cytochromes are required both by the process of respiration and photosynthesis.Both respiration and photosynthesis require cytochromes as these are the haem bound proteins that help in electron transfer also called electron transfer agents that help in the release of energy which is obtained in the form of energy.

Cytochromes are iron containing proteins, which are embedded in the inner mitochondrial membrane. These proteins serve as electron carrier proteins during mitochondrial electron transport chain. The mitochondrial electron transport chain is an important constituent of cellular respiration process.

Isoenzymes are an unique example in which the same reaction may be catalyzed by two or more different molecular forms of an enzyme. The multiple forms, called isozymes or isoenzymes, may occur in the same species, in the same tissue, or even in the same cell. The different forms of the enzyme generally differ in kinetic or regulatory properties, in the cofactor they use (NADH or NADPH for dehydrogenase isozymes, for example), or in their subcellular distribution (soluble or membrane-bound). Isozymes may have similar, but not identical, amino acid sequences, and in many cases they clearly share a common evolutionary origin. One of the first enzymes found to have isozymes was lactate dehydrogenase (LDH), which, in vertebrate tissues, exists as at least five different isozymes separable by electrophoresis. However, isoenzymes follow the same general mechanism of enzyme action, i.e., decreasing the activation energy of substrates for a reaction.

Glycolysis, the metabolic pathway that converts glucose into pyruvate, results in the net production of 2 ATP molecules, 2 NADH molecules, and 2 pyruvate molecules. During the energy-yielding phase of glycolysis, two molecules of ATP are produced through substrate-level phosphorylation. Additionally, for each glucose molecule, two molecules of NADH are generated through the reduction of NAD⁺ to NADH. Finally, two molecules of pyruvate are formed as the end product of glycolysis.

Kreb cycle is also known as the citric acid cycle or tricarboxylic acid cycle takes place in the inner membrane of mitochondria. It occurs there because the necessary enzyme for the Krebs cycle, succinic dehydrogenase is only found in the inner membrane of the mitochondria.
This is the only enzyme that has FAD as coenzymes and thus there is a formation of FADH₂ molecule.
Mitochondria are only associated with aerobic respiration.
So, the correct option is 'Mitochondrial matrix'.

During germination the respiration rate of seed is very high which release very high amount of energy and around 30 to 40% of energy is converted into ATP and utilize by the plant for its growth and rest is evolved in the form of heat which can be detected.
So the correct option is 'Heat'.

Respiration occurs in two stages. In the first stage called as glycolysis, which occurs in the absence of oxygen, one molecule of hexose glucose is broken down into two molecules of three carbon atom containing pyruvic acid. Each molecule of pyruvic acid is then oxidatively decarboxylated by the enzyme pyruvate dehydrogenase. The pyruvate dehydrogenase releases one molecule of carbon dioxide from each molecule of pyruvic acid during its conversion to Acetyl CoA. The Acetyl CoA is subsequently metabolised in Krebs cycle generating reduced coenzymes.

The respiration process can be aerobic or anaerobic. In both the processes glycolysis, which occurs in absence of oxygen is common. Glycolysis converts one molecule of glucose into two molecules of pyruvic acid. In aerobic respiration pyruvic acid is completely metabolised to carbon dioxide and water releasing lot of energy. In anaerobic respiration the pyruvic acid is incompletely metabolised to ethanol or lactate releasing far less amount of energy as compared to aerobic respiration.

Sequence of chemical reactions catalyzed by cellular enzymes occurring in the cytoplasm of cells that breaks down glucose, that releases energy stored as ATP is called glycolysis.
One molecule of glucose makes two molecules of pyruvate and two molecules of ATP. The pyruvate either enters into the tricarboxylic acid cycle (mitochondrial matrix) in presence of adequate oxygen or is fermented into lactic acid or ethanol. Thus, glycolysis produces both ATP for cellular energy requirements and building blocks for synthesis of other cellular products.This process occurs in all organisms, and is responsible for converting glucose to pyruvate and generating ATP in the process. Glycolysis does not require oxygen to function.

The universal hydrogen acceptor is NAD (Nicotinamide adenine dinucleotide). It is knows as universal hydrogen acceptor because it gets easily reduced by combining with a hydrogen bond.