Question

Why do animals need to breathe in oxygen?
a) To inflate their lungs so they can float.
b) To cool down their blood temperature.
c) To be used in cellular respiration to break down glucose.
d) To create water inside the stomach.
2. Which organism below performs cellular respiration?
a) A sunflower
b) A human
c) A mushroom
d) All of the above

Answer 1

1. c) To be used in cellular respiration to break down glucose.
- Oxygen is the final electron acceptor in aerobic cellular respiration, allowing cells to extract energy (ATP) from glucose. It’s not for inflating lungs, cooling blood, or making water in the stomach (though a small amount of water is produced inside mitochondria as a byproduct of respiration).

2. d) All of the above.
- Sunflowers (plants), humans (animals), and mushrooms (fungi) all perform cellular respiration to produce ATP. Plants do both photosynthesis and respiration; fungi respire as well.