Question

A scientist cultured some single-celled amoebae which he fed with cells of smaller single-celled
organisms. If he genetically modified these amoebae so that the hydrogen ion pumps found in the membrane of lysosomes only worked at temperatures below 16°C, what would happen if the temperature was raised to 20°C?

a. The lysosomes would burst open.
b. The amoebae would die instantly because of the high level of hydrogen ions in the cytoplasm.
c. The amoebae would swell and burst.
d. The amoebae would starve to death.
e. The lysosomes would disappear.

Answer 1

Answer given is d

The hydrogen ion pumps are in lysosome but not in mitochondria.... so why will it starve to death?
thanks :)

Answer 2

The amoebae will starve to death because there will not be enough hydrogen ions (protons) to sustain the proton gradient that makes the mitochondria work, that's to produce ATP.

Answer 3

but it's not talking about mitochondria but " the membrane of lysosomes"

Answer 4

Hmm....

Here's what I'm thinking: without working hydrogen ion pumps, the pH of the lysosomes steadily increases (H+ content drops). Without a thoroughly acidic environment, the enzymes of the lysosomes fail to function (this is the mechanism preventing them from gobbling up the cell itself when released!). Thus, without working hydrolytic enzymes, the amoeba cannot digest the smaller cells --> D; the amoeba would starve.

You may wonder, since the H+ content of the lysosomes is decreasing (and that of the cytoplasm is increasing) why C does not occur. This is a result of the amoeba's contractile vacuole - it is well adapted to excreting(?) water.

The other answer choices don't really make much sense, so I disregarded them.