RESPIRATION IN PLANT - 07-10-23

If O₂ is not present, yeast cells break down glucose to –

• (a) CO₂ + H₂O

• (b) CO₂ + Lactic acid

• (c) CO₂ + Pyruvic acid

• (d) C₂H₅OH and CO₂

NAD⁺ is –

• (a) a protein

• (b) an oxidising agent

• (c) a reducing agent

• (d) formed under only aerobic conditions

In terms of efficiency at converting the energy of glucose in ATP –

• (a) aerobic glycolysis is better than TCA cycle

• (b) eukaryotic cells are more efficient than prokaryotic cells

• (c) Electron transport chain is not necessary for high efficiency

• (d) Anaerobic conditions are much less efficient than aerobic

Which of the following statements about cellular energy-harvesting pathway is false?

• (a) Autotrophs can produce their own food but must obtain energy from it by glycolysis and cellular respiration

• (b) Fermentation usually occurs under anaerobic conditions

• (c) Pyruvate oxidation can only occur under aerobic conditions

• (d) None

Which of the following statements regarding metabolic pathways is false?

• (a) Many of the steps of glycolysis can run in reverse

• (b) Starch, sucrose or glycogen must be hydrolysed before it can enter the glycolysis

• (c) After fats are digested glycerol enters glycolysis by forming DHAP

• (d) After fats digestion, fatty acids can no longer participate in cellular respiration

In Kreb’s cycle –

• (a) Acetyl coenzyme A undergoes 4 oxidations and 2 decarboxylations

• (b) Pyruvic acid undergoes 4 oxidations and 2 decarboxylations

• (c) TCA undergoes 4 oxidations and 4 decarboxylations

• (d) OAA undergoes 4 oxidations and 2 decarboxylations.

Kreb’s cycle is also called TCA (Tri Carboxylic acid Cycle) or citric acid cycle (Organic acid cycle). It is also called metabolic sink as it is –

• (a) Common pathway for carbohydrates, fats and proteins (amino acids)

• (b) Common pathway for carbohydrates and fats only

• (c) Common pathway for carbohydrates and organic acids only

• (d) None of the above

The first reaction of Kreb’s cycle i.e. condensation of acetyl group with OAA and water is catalysed by –

• (a) Citrate synthetase

• (b) Succinate dehydrogenase

• (c) RuBisCo

• (d) PEPCase

Which one is correct?

• (a) Kreb’s cycle and chemiosmosis are inhibited in anaerobic conditions

• (b) Both glucose and fructose readily enter the glycolytic pathway

• (c) Glucose and fructose are phosphorylated by Hexokinase

• (d) All

If 2 acetyl CoA molecules are fed into the Kreb’s cycle, how many ATP molecules are synthesised directly in the cycle?

• (a) 2

• (b) 4

• (c) 36

• (d) 38