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CBSE Questions for Class 11 Medical Biology Respiration In Plants Quiz 1 - MCQExams.com
CBSE
Class 11 Medical Biology
Respiration In Plants
Quiz 1
An enzyme not used in Krebs cycle is
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Aconitase.
0%
Decarboxylase.
0%
Fumarase.
0%
Aldolase.
Explanation
Aconitase, decarboxylase, and fumarase are the enzymes used in the Krebs cycle but enzyme Aldolase is absent in Krebs cycle but present in glycolysis.
So the correct option is 'Aldolase.'
Enzyme of TCA which is located in inner mitochondrial membrane in eukaryotes and cytosol in prokaryotes is ?
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Lactate dehydrogenase
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Malate dehydrogenase
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Isocitrate dehydrogenase
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Succinate dehydrogenase
In which step of Krebs cycle,
CO$$_2$$ is evolved _________________.
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Isocitric acid Oxalosuccinic acid
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Succinic acid Fumaric acid
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Oxalosuccinic acid -ketoglutaric acid
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Maleic acid Oxaloacetic acid
In glycolysis, 6-C compounds are split into 3-C compounds by enzyme
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0%
Isomerase
0%
Aldolase
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Hexokinase
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Dehydrogenase
Explanation
A 6-C molecule i.e., Fructose 1,6-biphosphate is converted into two 3-carbon molecules, glyceraldehyde-3-phosphate (G3P) and dihydroxyacetone phosphate (DHAP), and the reaction is catalyzed by an enzyme aldolase.
So, the correct option is 'Aldolase'.
Which of the following is the product of phosphorylation?
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PGA
0%
Fructose 1,6-diphosphate
0%
DPGA
0%
Pyruvic acid
Explanation
Fructose 1,6-bisphosphate (f
ructose 1,6-diphosphate)
is formed as a result of phosphorylation of fructose-6-phosphate. It is a product of glycolysis. This step occurs in presence of phosphofructokinase.
So, the correct answer is option B.
Glycolysis occurs in
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Generally in all the cells
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In only eukaryotes
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Only in prokaryotes
0%
Only in higher animals
Explanation
Glycolysis occurs in cytoplasm of cells in anaerobic as well as aerobic respiration.
Harden and Young's ester is formed during glycolysis from
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Fructose1,6-bisphosphate
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Glucose-6-phosphate
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Glucose 1,6-bisphosphate
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fructose 6-phosphate
Krebs cycle is categorized as
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Anaerobic respiration
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Photorespiration
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Photosynthesis
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Aerobic respiration
Explanation
Krebs cycle is the cycle of chemical reactions taking place in mitochondria and requires oxygen, so it forms a part of aerobic respiration.
Krebs cycle begins with
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Pyruvic acid
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Hydrochloric acid
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Corticosteroids
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Lysine
Explanation
Pyruvic acid is the final product of glycolysis. It is then used as respiratory substrate for Krebs cycle. Thus, Kreb's cycle begins with pyruvic acid.
Acetyl CoA reacts with OAA to form
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Formaldehyde
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Acetate
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Isocitrate
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Citrate
Explanation
Acetyl CoA thus formed from pyruvic acid in the link reaction can now enter Krebs' cycle by combining with oxaloacetic acid. OAA and acetyl CoA form a 6-carbon compound citric acid as first product of the cycle.
So, the correct answer is 'Citrate'.
Intermediate common to fatty acid and carbohydrate oxidation is ____________.
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Pyruvate
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Acetyl CoA
0%
Oxaloacetate
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Succinate
Ethyl alcohol fermentation can be observed in
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Rhizopus
0%
Lactobacillus
0%
Mesophyll cell
0%
RBC
Explanation
While Saccharomyces cerevisiae is the most important source of industrial alcohol, R. stolonifer and other species of Rhizopus also produce ethyl alcohol which is the most important fermentation product.
So, the correct answer is 'Rhizopus'.
Which one of the following compounds in the photosynthetic electron transport chain contains copper?
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Cytochrome
0%
Ferredoxin
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Plastoquinone
0%
Plastocyanin
In the first step glycolysis, the phosphorylation of glucose is coupled to _______________.
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The reduction of NAD$$+$$
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The synthesis of ATP
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The hydrolysis of ATP
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The loss of electron
The number of $$NAD{ H }_{ 2 }s$$ formed in the complete aerobic respiration of one molecule of glucose are :
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12
0%
4
0%
10
0%
6
Identify from the following, the compound that links glycolysis and Kreb's cycle.
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Pyruvic acid
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Oxalo acetic acid
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Acetyl Co-A
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Lactic acid
The number of times hydration takes place in one Kreb's cycle is :
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6
0%
4
0%
3
0%
2
Co-operation between PS I and PS II is shown below by figure, find out $$A, B, C$$ and $$D, E$$ in given figure.
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(A) $$NADP$$ (B) $$NADPH + H^{+}$$ (C) $$FADH_{2}$$ (D) $$NADH_{2}$$
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(A) $$NADPH + H^{+}$$ (B) $$NADP$$ (C) $$ATP$$ (D) $$ADP$$
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(A) ADP (B) ATP (C) NADP (D) NADPH (E) Inorganic phosphate
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(A) ADP (B) ATP (C) NADP (D) NADPH (E) electrons
What is the site of the Krebs cycle in cells?
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Nucleus
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Cytoplasm
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Plastids
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Mitochondria
Explanation
The Krebs cycle or Tricarboxylic acid cycle takes place in the matrix of the mitochondria. Here, substrates like Carbohydrates, fats and proteins are oxidised in presence of various enzymes and Oxygen to release ATP.
So, the correct answer is '
Mitochondria'
Foul smell in the water of tanks, ponds etc., is due to:
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Anaerobiosis
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Aerobiosis
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Biological magnification
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Psammophytes
Explanation
Organic loading is occurrence of excess organic matter inside water. Its putrefaction decreases dissolved oxygen. Anaerobic putrefaction or anaerobiosis produces pollutants like methane, hydrogen sulphide and ammonia. They kill aquatic plants and animals. The water body comes to have foul smell, brown colouration, bad taste and oil.
How many pyruvate produced by oxidation of $$1$$ glucose molecule?
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Two
0%
Three
0%
One
0%
Four
Explanation
Glycolysis is the cellular metabolic pathway of simple sugar glucose to yield pyruvate and ATP as an energy source.
Two pyruvate molecules are produced by the oxidation of each one glucose molecule as shown in the above diagram.
Mechanism of aerobic respiration was discovered by
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Kreb
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Calvin
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Hatch and Slack
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Pasteur
Explanation
Mechanism of aerobic respiration was given by Kreb. Thus it was named as Krebs cycle. Aerobic respiration is the respiration, which involves the breakdown of the substrate in the presence of oxygen (oxidation process).
R.Q (respiratory quotient) is defined as:
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Volume of $$CO_{2}$$ evolved$$ = $$Volume of $$O_{2}$$ consumed
0%
Volume of $$O_{2}$$ consumed/
Volume of $$CO_{2}$$ evolved
0%
Volume of $$CO_{2}$$ consumed/
Volume of $$O_{2}$$ evolved
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Volume of $$CO_{2}$$ evolved/
Volume of $$O_{2}$$ consumed
Explanation
Respiratory quotient is the ratio, which could be calculated by dividing the volume of $$CO_2$$ eliminated to that of the volume of $$O_2$$ consumed.
Which statement is wrong for Krebs cycle?
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The cycle starts with condensation of acetyl group (acetyl Co-A) with pyruvic acid to yield citric acid.
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There are three points in the cycle where NAD$$^+$$ is reduced to NADH + H$$^+$$.
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There is one point in the cycle where FAD$$^+$$ is reduced to FADH$${_2}$$.
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During conversion of succinyl Co-A to succinic acid, a molecule of GTP is synthesised.
Explanation
Krebs cycle is t
he reactions that help in converting pyruvic acid to carbon dioxide and water in mitochondria.
In the first step, acetyl-CoA undergoes condensation with the oxaloacetic acid to yield citric acid. This reaction is catalyzed by the enzyme citric acid synthetase. Since citric acid is the first intermediate formed in Krebs cycle it is also called
citric acid cycle.
Thus the correct answer is option A.
Conversion of glucose to glucose-$$6$$-phosphate, the first irreversible reaction of glycolysis, is catalysed by?
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Aldolase
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Hexokinase
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Enolase
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Phosphofructokinase
Explanation
Hexokinase catalyses the conversion of Glucose to Glucose-$$6$$-phosphate. It is the first step of activation phase of glycolysis.
So, the correct answer is '
Hexokinase'
Which of the following reaction needs catalyses by decarboxylase enzyme?
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Conversion of citric acid to cis-aconitic acid
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Fumaric acid to malic acid
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Oxalosuccinic acid to $$\alpha$$-ketoglutaric acid
0%
Malic acid to oxaloacetic acid
Explanation
Oxalosuccinate is decarboxylated to form $$\alpha$$-ketoglutarate through the enzyme decarboxylase. It is one of the steps involved in Krebs cycle. It releases one molecule of $$CO_2$$.
Oxalosuccinate$$\overset{Decarboxylase}{\underset{Mg^{2+}}{\rightarrow}} \alpha$$-ketoglutarate$$+CO_2$$
After glycolysis, the fate of glucose in mitochondrial matrix is
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Oxidation.
0%
Reduction.
0%
Oxidative decarboxylation.
0%
Hydrolysis.
Explanation
After glycolysis, pyruvate forms acetyl Co-A which undergoes oxidation to form $$\displaystyle { CO }_{ 2 }$$ and $$\displaystyle { H }_{ 2 }O$$ through Krebs cycle in mitochondrial matrix.
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Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
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Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
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Assertion is correct but Reason is incorrect
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Both Assertion and Reason are incorrect
Explanation
One of the two phosphates of 1, 3-biphosphoglycerate (BPGA) is linked by high energy bond. It can synthesize ATP and form 3-phosphoglycerate by phosphoglycerate kinase enzyme. The direct synthesis of ATP from metabolites is called substrate-level phosphorylation.
Glycolysis is found in cytoplasm of virtually all type of aerobic/anaerobic cells. In the process, glucose is converted into a compound which is
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0%
PEP
0%
Pyruvic acid
0%
Acetyl CoA
0%
Citric acid
Explanation
Glycolysis process takes place in cytoplasm of cell. It is the metabolic pathway the converts glucose to pyruvate. The free energy released in this process are used to form the high-energy compounds ATP and $$NADH_2$$.
ATP formation occurs through which of the following.
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Photophosphorylation
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Oxidative phosphorylation
0%
Substrate level phosphorylation
0%
All of these
Explanation
In the process of photosynthesis, the phosphorylation of ADP to form ATP using the energy of sunlight is called photophosphorylation.
Oxidative phosphorylation is the process in which ATP is formed as a result of the transfer of electrons from NADH or$$FADH_2$$ to $$O_ 2$$ by a series of electron carriers. This process, which takes place in mitochondria, is the major source of ATP in aerobic organisms.
Substrate-level phosphorylation is a metabolic reaction that results in the formation of ATP or GTP by the direct transfer of a phosphoryl group to ADP or GDP from another phosphorylated compound.
Hence, ATP formation occurs through Photophosphorylation, Oxidative phosphorylation and Substrate level phosphorylation.
So, the correct answer is 'All of these'
Respiratory quotient of carbohydrate is
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0%
Unity
0%
Greater than unity
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Less than unity
0%
Equal to five
Explanation
Respiratory quotient of carohydrate will be always unity, because the volume of $$CO_2$$ eliminated is the same as the volume of $$O_2$$ consumed.
The organism in which the Krebs cycle does occur in mitochondria is
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Yeast.
0%
Man.
0%
Ulothrix.
0%
Moulds.
Explanation
Respiration is a catabolic energy release process in which reduced substrates are broken down. The respiration can be aerobic or anaerobic. The process of glycolysis is common to aerobic and anaerobic respiration. It is a cytosolic process. After glycolysis, in aerobic respiration, Krebs cycle occurs in the mitochondrial matrix, followed by oxidation of reduced coenzymes through electron transport chain in the inner mitochondrial membrane. Krebs cycle and electron transport chain do not play a role in anaerobic respiration. Mitochondria is absent in prokaryotes like
E. coli.
Hence, prokaryotes like
E. coli
cannot carry out aerobic respiration.
In which of the following, respiration takes place in absence of oxygen?
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Man
0%
Potato
0%
Yeast
0%
Spirogyra
Explanation
Respiration is the catabolic process in which reduced substrates are broken down. The process of respiration can occur in presence of oxygen (aerobic respiration) or absence of oxygen (anaerobic respiration). The process of anaerobic respiration is also called as fermentation. In some microorganisms like yeast, the process of anaerobic respiration (fermentation) results in incomplete breakdown of glucose to ethanol and carbon dioxide.
Krebs cycle takes place in the
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0%
Vesicles of E.R.
0%
Mitochondrial matrix.
0%
Dictyosomes.
0%
Lysosomes.
Explanation
Respiration is a catabolic energy release process. Respiration comprises of breakdown of glucose through glycolysis and Krebs cycle and energy production through oxidative phosphorylation. The glycolysis occurs in cytoplasm, Krebs cycle in mitochondrial matrix and oxidative phosphorylation occurs through the electron transport carriers embedded in inner mitochondrial membrane.
Which of the following is widely accepted to respire in absence of oxygen?
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Yeast
0%
Potato
0%
Chlorella
0%
Grass
Explanation
Yeast can respire both aerobically as well as anaerobically. Under anaerobic conditions yeast carries out alcoholic fermentation. Thus, it yields carbon dioxide as a product after this process.
The end products of fermentation when sugar is used as raw materials is/are
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Alcohol and $$CO_2$$.
0%
Alcohol and pyruvate.
0%
$$CO_2$$.
0%
Alcohol.
Explanation
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. Glycolysis occurs in cell cytoplasm. The anaerobic respiration is a cytosolic process, which results in production of lactic acid (lactic acid fermentation) or ethanol and carbon dioxide (alcoholic fermentation).
Which of the following is formed during respiration?
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$$O_{2}$$ (Oxygen)
0%
$$CO_{2}$$ (Carbon dioxide)
0%
$$NO_{2}$$ (Nitrogen dioxide)
0%
$$SO_{2}$$ (Sulphur dioxide)
Explanation
During the process of respiration, oxygen is utilized, and carbon
dioxide, water and energy are released as products.
Krebs cycle is a type of
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Aerobic respiration
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Photosynthesis
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Transpiration
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Anaerobic respiration
Explanation
The respiration can be aerobic or anaerobic. The process of glycolysis is common to both aerobic and anaerobic respiration.
After glycolysis, in aerobic respiration, the Krebs cycle occurs in the mitochondrial matrix, followed by oxidation of reduced coenzymes through the electron transport chain in the inner mitochondrial membrane.
The Krebs cycle and electron transport chain do not play a role in anaerobic respiration.
So the correct answer is option A.
Krebs cycle takes place in the
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Mitochondrial matrix.
0%
Cytoplasm.
0%
Lysosome.
0%
Mitochondrial intermembrane space.
Explanation
The Krebs cycle is a part of cellular respiration. The Krebs cycle comes after the link reaction and provides the hydrogen and electrons needed for the electron transport chain. It takes place inside the matrix of mitochondria.
Alternate name for Krebs cycle is
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Glyoxylate cycle.
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Glycolate cycle.
0%
Citric acid cycle.
0%
EMP pathway.
Explanation
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.
In which part of the mitochondria does the Krebs cycle take place?
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Inner mitochondrial membrane
0%
Outer mitochondrial membrane
0%
Cristae
0%
Mitochondrial matrix
0%
Inter-membrane space
Explanation
The
Krebs cycle is also known as
citric acid cycle or tricarboxylic acid (TCA) cycle. This cycle involves series of reactions in which the energy is released by the break down of the molecules like carbohydrates, proteins and fats. The energy is released in the form of ATP. The reaction of this cycle is carried out in the mitochondrial matrix. The enzymes for this pathway are present in the matrix of the mitochondria.
Thus, the correct answer is option D.
Krebs' cycle takes place in
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Cytoplasm
0%
Chloroplast
0%
Nucleus
0%
Mitochondria
Explanation
Kreb's cycle takes place in the mitochondrial matrix. The pyruvate formed by the reduction of glucose in the glycolysis is broken into acetyl-CoA which enters the Kreb's cycle and condenses with oxaloacetate to form citrate. One pyruvate molecules produce 15 ATP and two pyruvate molecules lead to the production of 30 ATP.
So, the correct answer is option D.
The most common respiratory substrate is
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Glucose
0%
Sucrose
0%
Maltose
0%
Glycogen
Explanation
The various organic substances such as carbohydrates, fats and proteins are respired completely to carbon dioxide and water are called respiratory substrates. Under natural conditions only carbohydrates are used. Glucose being the simplest monosaccharide hexose molecule acts as the chief respiratory substrate.
Thus, the correct answer is option A.
Fermentation by yeast produces
I. Carbon dioxide
II. Oxygen
III. Water
IV. Alcohol
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0%
I only
0%
I and II
0%
I, II and III
0%
I, III and IV
0%
I and IV
Explanation
Fermentation is a metabolic process occurs in yeast and bacteria. It occurs in the absence of oxygen. The products produced by yeast includes carbon dioxide, water and ethanol. Glycolysis is the first step of fermentation pathways as well which produces pyruvate, however other steps Kreb's cycle etc. does not take place in the absence of oxygen. Hence option D is correct.
This process is extensively used in alcohol industry.
Excess ATP inhibits respiration by inhibiting one of the following enzymes
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Phosphofructokinase
0%
Hexokinase
0%
Pyruvic decarboxylase
0%
Aldolase
Explanation
Allosteric inhibition is caused by the inhibitor which attaches at the site other than active site and brings a conformational change in the enzyme which prevents the formation of enzyme substrate complex. Phosphofructokinase helps in the phosphorylation of fructose- 6- phosphate to fructose 1,6 biphosphate.
High levels of ATP
allosterically
inhibits the enzyme phosphofructokinase.
So, the correct answer is option A.
An initial reactant and final product of the Krebs cycle is
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Pyruvate.
0%
Glucose.
0%
Citric acid.
0%
NADH.
0%
Oxaloacetic acid.
Explanation
During the first step of Krebs cycle, oxalo acetic acid reacts with acetyl CoA to form citric acid. As Krebs cycle is a cyclic pathway, the initial reactant oxalo acetic acid also acts as final product of the cycle.
All of the following are products of the Krebs cycle, except
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0%
NADH
0%
FADH$$_2 $$
0%
ATP
0%
C$$_6$$H$$_{12}$$O$$_6$$
0%
CO$$_2$$
Explanation
Krebs cycle was discovered by Sir Hans Krebs. It is also called as the citric acid cycle because citric acid is the first product of this cycle. In eukaryotic organisms, Krebs cycle takes place in the matrix of mitochondrion because enzymes of this cycle are found in matrix except for succinic dehydrogenase which is located in the inner membrane of the mitochondrion. In prokaryotes, Krebs cycle occurs in the cytoplasm.
Krebs cycle is basically a catabolic reaction as it oxidizes acetyl Co-A and organic acids into C
O
2
and
H
2
O. One molecule of pyruvic acid after entering into mitochondrion undergoes three decarboxylation and five oxidation steps. On oxidation, one molecule of pyruvic acid through Krebs cycle yields 15 ATP. Krebs cycle involves eight steps to oxidise two molecules of acetyl Co-A produced in transition reaction completely into 4C
O
2
, 10
H
2
O , 2ATP, 2FAD
H
2
and 6NADH +
H
+
. Hence
C
6
H
12
O
6
is not the product of Krebs cycle.
So, the correct answer is '
C
6
H
12
O
6
'.
Which of the following is true for TCA cycle in eukaryotes?
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Takes place in mitochondria
0%
Produces no ATP
0%
Takes place in Golgi complex
0%
Independent of electron transport chain
Explanation
The cyclic process through which acetyl co A is oxidized to form carbon dioxide and NADH$$_2$$ and FADH$$_2$$ (not ATP directly ) is known as Kreb cycle or TCA cycle. As it takes place in mitochondria matrix it is also known as the mitochondrial cycle. Thus, the correct answer is option A.
Ethyl alcohol or lactic acid is produced by the process of
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0%
Protein synthesis
0%
Respiration
0%
Digestion
0%
Photosynthesis
0%
Fermentation
Phosphorylation of glucose with the help of ATP and hexokinase produces
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0%
Glucose 1 - phosphate
0%
Glucose 6 - phosphate
0%
Glucose 1,6 - biphosphate
0%
Fructose, 1,6 - biphosphate
Explanation
The mechanism of respiration is initiated by breaking down of glucose to pyruvic acid without the help of oxygen. The initial process occurs in the cytosol of cells which requires glucose as well as ATP molecules which provide energy for the process to start. The first step of glycolytic pathway involves the phosphorylation of glucose in the presence of ATP to form glucose-6-phosphate. The reaction is catalyzed by enzyme hexokinase which requires a divalent magnesium ion as a cofactor. ATP is converted into ADP in this reaction.
Thus, the correct answer is option B.
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