Biology

Cellular Respiration and Enzymes

1,551 Questions

Explore key concepts of cellular respiration, including glycolysis, the Krebs cycle, and the electron transport chain. These questions also cover ATP production, anaerobic respiration, and essential metabolic pathways. This topic forms a core part of the biology syllabus for many competitive examinations.

Glycolysis and metabolic pathwaysKrebs cycle processesElectron transport chainATP production countAnaerobic respiration products

Cellular Respiration and Enzymes Questions

Multiple choice biology mineral nutrition in plants hydroponics nutrients and nutrition hydroculture

There is no direct transfer of electron from cyt b to cyt c as

  1. Energy is not available

  2. The two are not nearby

  3. Electrons are transported in pairs

  4. Electrons have no affinity for cytochromes
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In the electron transport chain, cytochrome b and cytochrome c are separated by the Q-cycle and the Rieske iron-sulfur protein. They are not directly adjacent in the membrane complex.

Multiple choice zoology the endocrine system adrenal gland thymus and adrenal gland adrenal glands

The sympathetic nervous system is responsible for the fight-or-flight response in humans. One neurotransmitter involved in this response is epinephrine. This excitatory molecule increases blood glucose by signaling the conversion of pyruvate into glucose.
Identify a potential target receptor cell of epinephrine in the fight-or-flight response.

  1. Liver cells.

  2. Cells in the pancreas that produce insulin.

  3. There is a specific target cell since epinephrine will work on all cells in the body and only cause a response in cells with intracellular receptors.

  4. Lung cells.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Liver cells contain glucose stored in the form of glycogen (glucagon enzyme), which is converted to glucose and released in the blood stream to provide muscle cells and brain with the required energy to respond to the stimulus instantaneously during a fight-or -flight response.

So, epinephrine should have receptors sites on liver cells or adipose cells which store energy molecules
So, the correct answer is 'Liver cells'

Multiple choice zoology excretion and osmoregulation micturition urine and urine formation urine formation
Electron transport chain (ETC) is a set of __________ electron carries present in a specific sequence along mitochondrial membrane.

  1. seven, inner

  2. six, inner

  3. seven, outer

  4. six, outer
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In electron transport chain, there are 7 electron acceptors, which are as follows $Co-Q\rightarrow Cyt \,b\rightarrow Cyt \,{c} _{1} \rightarrow Cyt \,c\rightarrow Cyt a\rightarrow Cyt \,{a} _{3}\rightarrow{O} _{2}$. Oxygen is the ultimate electron acceptor. These electron acceptors are present in a specific sequence along inner mitochondrial membrane.

Multiple choice chemistry endothermic and exothermic reactions endothermic reactions what are enthalpy changes energy change in chemical reactions

The process of respiration is:

  1. an oxidation reaction which is endothermic

  2. a reduction reaction which is exothermic

  3. a combination reaction which is endothermic

  4. an oxidation reaction which is exothermic
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The process of respiration is an oxidation reaction which is exothermic.
Respiration is considered as an exothermic reaction because in respiration oxidation of glucose takes place which produces large amount of heat energy. 

Multiple choice chemistry endothermic and exothermic reactions endothermic reactions what are enthalpy changes energy change in chemical reactions

To start, every biochemical reaction is:

  1. exergonic

  2. endergonic
  3. both $A$ and $B$

  4. none of the above.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Since any chemical reaction requires some energy of activation to start with, so this step is endergonic or since biochemical reaction is also a type of chemical reaction, so its first step is endothermic or endergonic.

Multiple choice microbiology: organisms in industry option b: biotechnology and bioinformatics biology

The citric acid cycle _________________.

  1. Contains intermediates for amino acid synthesis

  2. Generates fewer molecules of ATP than glycolysis

  3. Is an anaerobic process

  4. Is the major anabolic pathway for glucose synthesis
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The citric acid cycle provides precursors (intermediates) for the biosynthesis of various amino acids, making it amphibolic.

Multiple choice microbiology: organisms in industry option b: biotechnology and bioinformatics biology

Alcoholic dehydrogenase gets activated by?

  1. $Mg^{++}$

  2. Mo
  3. $Zn^{++}$

  4. K
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Alcoholic dehydrogenase is an enzyme required during the anaerobic respiration to convert the aldehyde to the ethanol. Its activity is enhanced by the presence of Mg$^{++}$ ions that allow the NADPH to combine for oxidation to NADP.

Hence, the correct answer is 'Mg$^{++}$'.

Multiple choice muscle contraction locomotion and movements biology

In hurdle race, what is the major energy source of the leg muscle?

  1. ATP

  2. Glycolysis

  3. Pyruvate and lactate

  4. Oxidative metabolism
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • The source of energy that is used to power the movement of contraction in working muscles is adenosine triphosphate (ATP).
  • ATP is considered as the energy currency of the cell.
  • Hence In a hurdle race, what is the major energy source of the leg muscle ATP. It helps in muscle contraction that facilitates running in the race.
  • So, the correct answer is 'ATP'.
Multiple choice muscle contraction locomotion and movements biology

In hurdle race, what is major source of energy to leg muscle?

  1. Preformed ATP

  2. Oxidative metabolism

  3. Pyruvate and lactate

  4. Glycolysis
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

  • In the hurdle race, a person requires energy production faster than our bodies can adequately deliver oxygen. 
  • In those cases, the working muscles generate energy anaerobically. This energy comes from glucose through a process called glycolysis, in which glucose is broken down or metabolized into a substance called pyruvate through a series of steps.
  •  When oxygen is limited, the body temporarily converts pyruvate into a substance called lactate, which allows glucose breakdown and thus energy production to continue.
  •  The working muscle cells can continue this type of anaerobic energy production at high rates for one to three minutes, during which lactate can accumulate to high levels.
Hence, In the hurdle race,  Oxidative metabolism is a major source of energy to the leg muscle.
   So, the correct answer is 'Oxidative metabolism'.

Multiple choice muscle contraction locomotion and movements biology

Immediate source of energy for muscle contraction is

  1. Glucose

  2. GTP

  3. Creatine phosphate

  4. ATP
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
  •  Active sites for myosin are present on actin which are masked by troponin in resting state. When Ca++ level increases it leads to the binding of calcium with a subunit of troponin on actin(thin) filaments and thereby remove the masking of active sites for myosin.
  • Utilizing the energy from ATP hydrolysis, the myosin head now binds to the exposed active sites on actin to form a cross bridge. 
  • This pulls the attached actin filaments towards the centre of ‘A’ band.
  •  The ‘Z’ line attached to these actins are also pulled inwards thereby causing a shortening of the sarcomere, i.e., contraction. The myosin, releasing the ADP and P1 goes back to its relaxed state. Hence immediate source of energy for muscle contraction is ATP.
  • So, the correct answer is 'ATP'.
Multiple choice properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology

An enzyme acts by

  1. Reducing the energy of activation.

  2. Increasing the energy of activation.

  3. Decreasing the pH.

  4. Increasing the pH.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The reactants do not undergo chemical change automatically. They do so in transition state. Transition state has more free energy than reactants or products. The inability of reactants to undergo change due to requirement of extra energy for converting them to transition state is called as 'Energy Barrier'. Energy required to overcome energy barrier is called as 'Activation Energy'.

Multiple choice properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology

Select the correct option: 

Enzymes catalyze the biochemical reactions by .......... the activation energy.

  1. lowering

  2. increasing

  3. unaltering

  4. either (a) or (b)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Enzymes are macromolecular biological catalysts. which accelerates chemical reactions. Catalysts lower the activation energy (energy required to start a reaction.) for reactions. The lower the activation energy for a reaction, the faster the rate.

So, the correct answer is 'lowering'.

Multiple choice properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology
Enzymes that catalyse removal of groups from substrates by mechanisms other than hydrolysis, and addition of groups to double bonds, are called

  1. Ligase

  2. Lyase

  3. Hydrolase

  4. Dehydrogenase
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Lyases enzymes catalyse the breakage of specific covalent bonds and removal of group with out hydrolysis producing double bonds or removal of double bonds by adding group,e.g., histidine decarboxylase that splits $C-C$ bond of histidine,forming $CO _2$ and histamine.

${\overset{X}{\overset{|}C}}-{\overset{Y}{\overset{|}C}} \xrightarrow{lyase}X-Y+C=C$