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 nutrition and respiration importance of light for photosynthesis various experiments on photosynthesis experiments on photosynthesis - gases

In the experiment " To show that $CO _{2}$ is given out during respiration" the water level in the bent tube rise after sometime because

  1. germinating seeds consume all the $O _{2}$ and $CO _{2}$ in the flask.
  2. the germinating seeds consume $O _{2}$ and give out $CO _{2}$ which is absorbed by a chemical filled in the small test tube.
  3. $CO _{2}$ is given out by the germinating seeds.

  4. seeds need water for germination and grow.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Germinating seeds respire, consuming O2 and releasing CO2. The KOH solution in the small test tube absorbs the CO2, creating a partial vacuum in the flask, which causes the water level in the bent tube to rise.

Multiple choice biomacromolecules biotechnology cell biology and biotechnology biomolecules biology

What is common between NAD and FAD?

  1. Both are coenzymes

  2. Both are derived from proteins

  3. Both acts as oxygen carriers

  4. All of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Nicotinamide Adenine Dinucleotide (NAD) and Flavin Adenine Dinucleotide (FAD) are coenzymes associated with reversible oxidation and decrease reactions. Then, these lessened coenzymes can give these electrons to some other biochemical response ordinarily engaged with a procedure that is anabolic (like the union of ATP).

So, the correct option is 'Both are coenzymes'.

Multiple choice biology respiration and energy transfer respiratory quotient-basic respiration-plants respiratory quotient

R. Q in anaerobic respiration is 

  1. 0
  2. ${\propto }$

  3. 1

  4. > 1
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The respiratory quotient (RQ) is the ratio of $CO _2$ produced to $O _2$ consumed, while food is being metabolized.
RQ = $CO _2$ eliminated / $O _2$ consumed.
The value of RQ is infinity during anaerobic respiration, because $CO _2$ is produced but $O _2$ is not utilized. Thus, option B is correct and other options are incorrect.

Multiple choice biology respiration and energy transfer respiratory quotient-basic respiration-plants respiratory quotient

In succulent plants R.Q. is less than one because of

  1. Complete oxidation

  2. Complete reduction

  3. Incomplete reduction

  4. Incomplete oxidation
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In succulent plants, the stomata are open during night and during this time plants absorb carbon dioxide. During day time stomata are closed and no carbon dioxide is evolved. These plants respire during night time, when they can take oxygen through open stomata. The volume of carbon dioxide is less than typical aerobic respiration. In fact during night time, these plants fix carbon dioxide into organic acids. The respiratory substrates are incompletely oxidised and thus, respiratory quotient is less than one.

Multiple choice biology respiration and energy transfer respiratory quotient-basic respiration-plants respiratory quotient

When the evolution of $CO _2$ is more than the intake of $O _2$, the respired substrate should be

  1. Fatty acid.

  2. Organic acid.

  3. Glucose.

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

The respiratory quotient depends upon the type of respiratory substrate used during respiration. When organic acids are metabolised more carbon dioxide is evolved than oxygen consumed. Hence, the value of RQ is more than one.

Multiple choice biology respiration and energy transfer respiratory quotient-basic respiration-plants respiratory quotient

Respiratory quotient of which diet is less than unity?

  1. Carbohydrate

  2. Fats

  3. Organic acid

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

Respiratory quotient (RQ) is defined as the volume of carbon dioxide released to the volume of oxygen absorbed during the process of aerobic respiration. 

As fats are considerably much more reduced form of carbon as compared to carbohydrates and organic acids, their respiration requires much more oxygen as compared to respiration of sugars (carbohydrates) or organic acids. Thus, the value of RQ for fats is less than one.

Multiple choice biology respiration and energy transfer respiratory quotient-basic respiration-plants respiratory quotient

R.Q. would depend upon

  1. Nature of enzymes

  2. Nature of substrate
  3. Amount of CO$ _2$ released
  4. Amount of O$ _2$ utilised
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Respiratory Quotient (R.Q.) is the ratio of the volume of CO$ _{2}$ released to the volume of O$ _{2}$ consumed in a respiration process. It depends on the nature of the substrate and its capacity of using O$ _{2}$ and releasing CO$ _{2}$. For example, glucose consumes 6 CO$ _{2}$ and releases 6 O$ _{2}$, so its R.Q. is 1.

 Hence, the correct answer is 'Nature of substrate'

Multiple choice biology respiration and energy transfer respiratory quotient-basic respiration-plants respiratory quotient

When the Respiratory Quotient (R.Q.) is greater than 1, it indicates

  1. Only aerobic respiration is taking place

  2. Only anaerobic respiration is taking place

  3. Both aerobic and anaerobic respiration are taking place

  4. None of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The respiratory quotient is used in calculations of BMR when estimated from carbon dioxide production. It is calculated from the ratio of carbon dioxide produced by the body to oxygen consumed by the body. A  value of 0.7 indicates that lipids are being metabolized, 0.8 for proteins, and 1.0 for carbohydrates. RQ can be used as an indicator of over or underfeeding. Underfeeding, which forces the body to utilize fat stores, will lower the RQ and is marked by an RQ below 0.85, while overfeeding, which causes lipogenesis, will increase it and is indicated by RQ greater than 1.0.

So, the correct option is 'none of these'. 

Multiple choice biology respiration and energy transfer respiratory quotient-basic respiration-plants respiratory quotient

The most common respiratory substrate is

  1. Glucose

  2. Sucrose

  3. Maltose

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

Multiple choice zoology respiratory system phases in respiration human respiratory system parts of respiration

Cellular respiration is

  1. Continuous

  2. Intermittent

  3. Performed at intervals

  4. Held when energy is required
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Cellular respiration is a continuous process of oxidation of food to produce energy. The energy produced is utilized by human beings to carry out all the life processes such as digestion, excretion, circulation etc. Since these are continuous processes and do not stop, so they require continuous energy. If the energy is produced intermittently it will slow down these processes and affect the individual. 

Thus, the correct answer is option A. 

Multiple choice zoology respiratory system phases in respiration human respiratory system parts of respiration

Full name of NADP is

  1. Nicotinamide dinucleotide phosphate

  2. Nicotine adenine dinucleotide phosphate

  3. Nicotinamide adenine dinucleotide phosphate

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Nicotinamide adenine dinucleotide phosphate, abbreviated NADP is a cofactor used in anabolic reactions, such as lipid and nucleic acid synthesis, which require NADPH as a reducing agent.

Multiple choice zoology respiratory system phases in respiration human respiratory system parts of respiration

Pyruvic acid is converted into a compound before formation of oxaloacetic acid in the citric acid cycle, this compound is

  1. Acetyl COA

  2. Acetoacetic acid

  3. Lactic acid

  4. Cis aconitic acid
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The end product of glycolysis is pyruvic acid. The next step is the formation of acetyl coenzyme A (acetyl CoA). Acetyl CoA is the initiator of the citric acid cycle. In carbohydrate metabolism, acetyl CoA is the link between glycolysis and the citric acid cycle. The initiating step of the citric acid cycle occurs when a four-carbon compound (oxaloacetic acid) condenses with acetyl CoA (2 carbons) to form a citric acid (6 carbons).

Multiple choice zoology respiratory system phases in respiration human respiratory system parts of respiration

State whether the following statements are true or false.
Because $NAD^+$ and FAD are critical coenzymes in cellular respiration, huge quantities must be synthesized in the cell to ensure there is no shortage.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

NAD+ and FAD are co-enzymes required for the completion of many biochemical pathways. However, there is no need for an enormous amount of synthesis of either of these co-enzymes as there as a mechanism of recycling the co-enzymes after completion of one step in the metabolic pathway. These co-enzymes are predominantly required for the synthesis of ATP (energy currency of the cell) and will be used in the electron transport chain for the production of the same. So, they are not required to be synthesized in huge quantities but they play a crucial role in cell energetics.

So, the correct statement is 'False'.