BIOLOGY PART 2

The number of ATP molecules produced by the Krebs Cycle per glucose molecule is

• 2

• 3

• 4

• 0

Answer explanation

The Krebs Cycle produces 2 ATP molecules per glucose molecule through substrate-level phosphorylation. This occurs during the conversion of succinyl-CoA to succinate, making the correct answer 2.

Krebs Cycle takes place in the:

• Cytoplasm

• Mitochondrial matrix

• Ribosome

• Intermembrane Space

Answer explanation

The Krebs Cycle, also known as the citric acid cycle, occurs in the mitochondrial matrix, where it plays a crucial role in cellular respiration by generating energy through the oxidation of acetyl-CoA.

Main products of the Calvin Cycle

• Oxygen, NADP+, ADP

• Glucose, CO2, ADP

• ADP, NADP+, Glucose

• ATP, NADPH, Oxygen

Answer explanation

The Calvin Cycle primarily produces ATP and NADPH, which are essential for the synthesis of glucose. Oxygen is released as a byproduct during photosynthesis, but it is not a main product of the Calvin Cycle itself.

The Calvin Cycle occurs in the

• Thylakoid

• Grana

• Inner membrane of chloroplast

• Stroma

Answer explanation

The Calvin Cycle, which is part of photosynthesis, occurs in the stroma of chloroplasts. This is where the necessary enzymes and substrates are available for the cycle to convert carbon dioxide into glucose.

Which of the following is true of the Calvin Cycle?

• carbon dioxide and energy (ATP and NADPH) are used to make organic compounds

• energy is absorbed from sunlight and converted to chemical energy stored in ATP and NADPH

• Occurs in the thylakoid

• Occurs in the cytoplasm

Answer explanation

The Calvin Cycle uses carbon dioxide along with energy from ATP and NADPH to synthesize organic compounds, making the first choice correct. The other options describe processes that occur in different stages of photosynthesis.

Nitrogen fixation...

• animals eat the plants and other animals that contain nitrogen and release it through their waste

• Bacteria in the soil and lightning in the atmosphere "fix" the nitrogen

• Once in the ground, bacteria in the soil also nitrify the nitrogen

• plants absorb nitrogen through their roots and return it back to the atmosphere

Answer explanation

Bacteria in the soil and lightning are key processes in nitrogen fixation, converting atmospheric nitrogen into forms usable by plants, making this the correct choice.

Nitrification...

• animals eat the plants and other animals that contain nitrogen and release it through their waste

• Bacteria in the soil and lightning in the atmosphere "fix" the nitrogen

• Once in the ground, bacteria in the soil also nitrify the nitrogen

• plants absorb nitrogen through their roots and return it back to the atmosphere

Answer explanation

Nitrification is the process where bacteria in the soil convert ammonia into nitrates, making nitrogen available for plants. Thus, the correct choice highlights that bacteria in the soil nitrify the nitrogen once it is in the ground.

13. Ammonification...

• a. animals eat the plants and other animals that contain nitrogen and release it through their waste

• b. Bacteria in the soil and lightning in the atmosphere "fix" the nitrogen

• c. Once in the ground, bacteria in the soil also nitrify the nitrogen

• d. plants absorb nitrogen through their roots and return it back to the atmosphere

Answer explanation

Ammonification occurs when animals consume nitrogen-containing plants and animals, releasing nitrogen back into the soil through their waste. This process is essential for recycling nitrogen in ecosystems.

Assimilation...

• animals eat the plants and other animals that contain nitrogen and release it through their waste

• Bacteria in the soil and lightning in the atmosphere "fix" the nitrogen

• Once in the ground, bacteria in the soil also nitrify the nitrogen

• plants absorb nitrogen through their roots and return it back to the atmosphere

Answer explanation

The correct answer is that plants absorb nitrogen through their roots and return it back to the atmosphere. This process is essential for the nitrogen cycle, allowing nitrogen to be utilized by living organisms.

15. Denitrification...

• animals eat the plants and other animals that contain nitrogen and release it through their waste

• Bacteria in the soil and lightning in the atmosphere "fix" the nitrogen

• nitrogen is released back into the atmosphere from the animal's waste or decomposers

• plants absorb nitrogen through their roots and return it back to the atmosphere

Answer explanation

Denitrification is the process where nitrogen is released back into the atmosphere, primarily from decomposers breaking down organic matter and from animal waste, making this choice the correct answer.