Energy and Respiration Grade 8 Quiz

What is ATP known as?

• Energy source

• Energy catalyst

• Energy storage

• Energy currency

Answer explanation

ATP is known as the "energy currency" of the cell because it stores and transfers energy for various cellular processes, making it essential for metabolism and energy transfer.

What is the process of adding a phosphate group to glucose called?

• Dehydrogenation

• Phosphorylation

• Oxidation

• Decarboxylation

Answer explanation

The process of adding a phosphate group to glucose is called phosphorylation. This modification is crucial for glucose metabolism, as it helps in trapping glucose within the cell and activating it for further biochemical reactions.

Where does glycolysis occur?

• Mitochondrion

• Cytoplasm

• Cell membrane

• Nucleus

Answer explanation

Glycolysis occurs in the cytoplasm of the cell, where glucose is broken down into pyruvate, producing energy in the form of ATP. This process does not take place in the mitochondrion, cell membrane, or nucleus.

What is produced during anaerobic respiration in animals?

• Lactic acid

• Oxygen

• Ethanol

• Carbon dioxide

Answer explanation

During anaerobic respiration in animals, glucose is converted into lactic acid when oxygen is scarce. This process allows for energy production without oxygen, making lactic acid the correct answer.

What is the end product of anaerobic respiration in plants?

• Ethanol

• Oxygen

• Lactic acid

• Glucose

Answer explanation

In plants, anaerobic respiration occurs in the absence of oxygen, resulting in the production of ethanol and carbon dioxide. Therefore, the correct answer is ethanol.

What happens to NAD during anaerobic respiration?

• It is regenerated

• It is oxidized

• It is reduced

• It is produced

Answer explanation

During anaerobic respiration, NAD is regenerated from NADH, allowing glycolysis to continue. This regeneration is crucial for producing ATP in the absence of oxygen, making 'It is regenerated' the correct choice.

What is the role of the electron transport chain?

• To break down pyruvate

• To synthesize ATP

• To pump hydrogen ions

• To produce glucose

Answer explanation

The electron transport chain primarily functions to pump hydrogen ions across the mitochondrial membrane, creating a proton gradient. This gradient is essential for ATP synthesis, but the main role is the pumping of hydrogen ions.

What is chemiosmosis?

• Breakdown of glucose

• Production of ATP

• Movement of ions across a membrane

• Transport of oxygen

Answer explanation

Chemiosmosis refers to the movement of ions, particularly protons, across a membrane, which creates a gradient used to produce ATP. This process is essential in cellular respiration and photosynthesis.

What is the first step in both aerobic and anaerobic respiration?

• Krebs cycle

• Glycolysis

• Link reaction

• Electron transport chain

Answer explanation

The first step in both aerobic and anaerobic respiration is glycolysis. This process breaks down glucose into pyruvate, producing ATP and NADH, and occurs in the cytoplasm regardless of the presence of oxygen.

What is formed when a phosphate group is removed from ATP?

• FAD

• NAD

• ADP

• AMP

Answer explanation

When a phosphate group is removed from ATP (adenosine triphosphate), it becomes ADP (adenosine diphosphate). This process releases energy that can be used for cellular activities.