8.7 + 8.8

Question 1

What is an Amphibolic Pathway?

Answer 1

A metabolic pathway that can function in both catabolism (breaking down) and anabolism (building up).

Question 2

What is the best example of an amphibolic pathway?

Answer 2

The Krebs Cycle (also called the TCA or Citric Acid cycle).

Question 3

Why is the Krebs Cycle considered amphibolic?

Answer 3

It breaks down Acetyl-CoA for energy, but its intermediates (like alpha-ketoglutarate) are used to build amino acids.

Question 4

Why are amphibolic pathways efficient?

Answer 4

They allow the cell to use the same enzymes and structures for multiple purposes, saving space and energy.

Question 5

Energy Source

Answer 5

Photo- (Light) vs. Chemo- (Chemicals).

Question 6

Carbon Source

Answer 6

Auto- (Inorganic CO_2) vs. Hetero- (Organic food/sugars).

Question 7

Define Phototroph vs. Chemotroph.

Answer 7

Phototroph: Gets energy from light.

Chemotroph: Gets energy from breaking chemical bonds.

Question 8

What category do most human pathogens fall into?

Answer 8

Chemoheterotrophs (they “eat” our organic molecules for both energy and carbon).

Question 9

Define Autotroph vs. Heterotroph.

Answer 9

Autotroph: Uses inorganic carbon (CO_2); “self-feeder.”
Heterotroph: Uses organic carbon (sugars, fats, proteins); “other-feeder.”

Question 10

Which group uses light for energy but must “eat” organic compounds for carbon?

Answer 10

Photoheterotrophs.

Question 11

What is the difference between a Saprobe and a Parasite?

Answer 11

Both are chemoheterotrophs, but Saprobes eat dead organic matter, while Parasites eat living host tissue.