3. Structure and regulation of biochemical pathways Part 3

Question 1

What is the first step of anaerobic respiration and what are the differences in products due to?

Answer 1

• The first step is glycolysis regardless or the organism

- The difference in products is due to the different enzymes found in the organisms

Question 2

Describe the difference in anaerobic respiration between plants and animals:

Answer 2

• In plants, yeast and bacteria, pyruvate is converted into ethanol and CO2
• In animals, pyruvate is converted into lactic acid (NO CO2)

Question 3

What are the differences in the location between aerobic and anaerobic respiration?

Answer 3

Aerobic respiration occurs in the cytoplasm and the mitochondria, while anaerobic respiration only occurs in the cytoplasm.

Question 4

What are the differences in the stages which occur in aerobic and anaerobic respiration?

Answer 4

• Aerobic respiration includes Glycolysis, Transition Reaction, Krebs Cycle, and the Electron Transport System
• Anaerobic respiration only includes Glycolysis

Question 5

What are the differences in the energy efficiency between aerobic and anaerobic respiration?

Answer 5

36 ATP are produced in aerobic respiration, while only 2 ATP are produced in anaerobic respiration.

Question 6

What are the differences in speed between aerobic and anaerobic respiration?

Answer 6

Aerobic respiration is slower than anaerobic respiration which is much faster.

Question 7

Describe the differences in some of the products produced by aerobic and anaerobic respiration:

Answer 7

• Aerobic respiration produces carbon dioxide (CO2) and water (H2O)
• Anaerobic respiration produces ethanol and carbon dioxide (CO2) in plants, and lactic acid in animals

Question 8

List 3 factors which affect the rate of cellular respiration:

Answer 8

• Temperature
• Supply of glucose
• Supply of oxygen

Question 9

Describe how temperature can affect the rate of cellular respiration:

Answer 9

Plants have lower growth rates and some animals hibernate which results in the minimisation of energy requirements.

Question 10

Describe how the supply of glucose can affect the rate of cellular respiration:

Answer 10

• Cells require an ongoing supply of glucose for cellular respiration
• If glucose stores become depleted pyruvate, lactic acid and lipids may be recycled to generate glucose molecules for cellular respiration.

Question 11

Where can multicellular organism store glucose?

Answer 11

• Plants as starch in granules

- Animals as glycogen in liver cells

Question 12

Describe how the supply of oxygen can affect the rate of cellular respiration:

Answer 12

• The availability of oxygen affects the switch from aerobic to anaerobic respiration.
• Anaerobic respiration is less efficient since only 2 ATP are generated from one glucose molecule compared to the 36 ATP generated from aerobic respiration.
• Anaerobic respiration is faster but requires the removal of accumulated products, such as lactic acid.

Question 13

What is the Endosymbiotic Theory?

Answer 13

Describes how a large host cell and ingested bacteria could easily become dependent on one another for survival, resulting in a permanent relationship.
-It is thought that over millions of years of evolution, mitochondria, and chloroplasts have become more specialised and today they cannot live outside the cell.

Question 14

Give 3 examples of evidence for the Endosymbiotic Theory:

Answer 14

• Mitochondria and chloroplasts make copies of themselves by breaking into two, similarly to how prokaryotes replicate by binary fission.
• Mitochondria and chloroplasts both contain their own circular DNA and ribosomes
• They both have two membranes, the outer one of which may have been derived from the host membrane when it engulfed the bacterium.

Question 15

What is the difference between structural and regulatory genes?

Answer 15

Regulatory genes produce a product which controls other genes, whereas structural genes produce proteins that don’t control other genes.

Question 16

List 3 examples of coenzymes:

Answer 16

ATP, NADPH, and NADH

Question 17

List the inputs and outputs for the overall equation of cellular respiration:

Answer 17

Inputs: Oxygen + Glucose
Outputs: Carbon dioxide + Water

Question 18

What is ATP and describe its function:

Answer 18

A coenzyme, which can help enzymes join small molecules together to make larger molecules (which requires energy).

• The energy in an ATP molecule is contained in one of its 3 phosphate bonds. When one phosphate is removed, energy is released and the ATP becomes ADP and an inorganic phosphate iron. These leave the enzyme, and a new ATP enters the active site of the enzyme ready for the next substrate.
• ADP then needs to go back to the mitochondrion, where it is regenerated to ATP in the process of cellular respiration.

Question 19

What is NADH and describe its function:

Answer 19

Is an energy carrier used is cells which works similarly to ATP.

• An NAD+ molecule gains an H iron thereby becoming NADH. The energy is contained in the bond holding the H. This can be broken to release that small amount of energy for use in the cell.
• NADH is produced and used in Cellular respiration.

Question 20

What is NADPH and describe its function:

Answer 20

Is similar to NADH and is the energy carrier that transports the Hydrogen ions that split off water molecules in the light-dependent stage of photosynthesis, to the light in independent reactions.