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KCSE Cellular Respiration — practice questions — page 3

Explore 86 free Cellular Respiration questions in KCSE Biology. Open each question or exercise to read its content, reference answers and available explanation.

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Cellular Respiration questions and exercises with answers

Showing questions 61–86 of 86.

What happens to the lactic acid that builds up in a working muscle?Read the answer and worked solution →Which enzyme catalyses the conversion of pyruvic acid to lactic acid?Read the answer and worked solution →What inhibits the forward direction of the reaction that turns pyruvic acid into lactic acid?Read the answer and worked solution →What is the current standing of the old belief that lactic acid build-up causes muscle stiffness and soreness?Read the answer and worked solution →In alcohol fermentation, what is produced when a carboxyl group leaves pyruvic acid?Read the answer and worked solution →What range of ethanol tolerance is reported for yeast, depending on strain and conditions?Read the answer and worked solution →How does oxygen affect an obligate anaerobe such as Clostridia?Read the answer and worked solution →Which single form of fermentation does not produce gas?Read the answer and worked solution →Which step of glycolysis would stall if no fermentation pathway were available in the absence of oxygen?Read the answer and worked solution →Into which two pathways do the catabolic routes for carbohydrates, proteins and lipids eventually connect?Read the answer and worked solution →Where is glycogen made and stored in animals?Read the answer and worked solution →What must be removed from an amino acid before its carbon skeleton can enter the pathways of glucose catabolism?Read the answer and worked solution →Glycerol from a triglyceride enters glucose metabolism after being changed into which compound?Read the answer and worked solution →What is the likely order of appearance of glycolysis and photosynthesis in the history of life?Read the answer and worked solution →What did the later form of photosynthesis use as its source of electrons and hydrogen?Read the answer and worked solution →What would happen to metabolic reactions in a cell without any regulatory controls?Read the answer and worked solution →Why does having two different enzymes for the two directions of a reversible reaction improve control?Read the answer and worked solution →Which molecules are most commonly used as allosteric effectors of respiratory enzymes?Read the answer and worked solution →How does an allosteric effector change the behaviour of an enzyme?Read the answer and worked solution →What happens to glucose in a tissue where hexokinase has been inhibited?Read the answer and worked solution →Which enzyme is described as the main controlled enzyme of glycolysis?Read the answer and worked solution →Besides being catabolized further, what else can the pyruvate produced by glycolysis become?Read the answer and worked solution →How is the rate of electron transport through the chain controlled?Read the answer and worked solution →Roughly what free energy do the electrons carried by NADH hold as they enter the electron transport chain?Read the answer and worked solution →Split the two electron carriersRead the answer and worked solution →Fill in the energy currency factsRead the answer and worked solution →

Worked practice questions

What happens to the lactic acid that builds up in a working muscle?

  1. It is stored inside the muscle fibres
  2. It is exhaled from the lungs as a gas
  3. It is carried in blood to the liver
  4. It is passed out unchanged in urine
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Correct answer: C. It is carried in blood to the liver

1. Lactic acid accumulation in muscles must be removed by the blood circulation. 2. The lactate is brought to the liver for further metabolism. 3. Once there, it can be reconverted into pyruvic acid and further catabolized for energy. 4. Urea, not lactate, is the nitrogen waste that leaves the body in urine. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 7 "Cellular Respiration", section 7.5 Metabolism without Oxygen_

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Which enzyme catalyses the conversion of pyruvic acid to lactic acid?

  1. Succinate dehydrogenase
  2. Alcohol dehydrogenase
  3. Pyruvate decarboxylase
  4. Lactate dehydrogenase
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Correct answer: D. Lactate dehydrogenase

1. Lactic acid fermentation converts pyruvic acid and NADH into lactic acid and the oxidized carrier. 2. The enzyme used in that reaction is lactate dehydrogenase. 3. Alcohol dehydrogenase belongs to the second reaction of alcohol fermentation instead. 4. Succinate dehydrogenase is a citric acid cycle enzyme embedded in the inner mitochondrial membrane. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 7 "Cellular Respiration", section 7.5 Metabolism without Oxygen_

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What inhibits the forward direction of the reaction that turns pyruvic acid into lactic acid?

  1. Acidic conditions
  2. Alkaline conditions
  3. Very cold conditions
  4. Very dry conditions
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Correct answer: A. Acidic conditions

1. The lactate dehydrogenase reaction can proceed in either direction. 2. The direction from pyruvic acid to lactic acid is inhibited by acidic conditions. 3. Lactic acid is itself an acid, so its build-up slows the very reaction that makes it. 4. That is a self-limiting arrangement rather than an outside control. 5. Alkaline conditions are not named as an inhibitor anywhere in this reaction. 6. Temperature and dryness play no stated part in the direction this reaction takes. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 7 "Cellular Respiration", section 7.5 Metabolism without Oxygen_

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