Question

At the start of the Krebs cycle, acetyl CoA reacts with which molecule to form citrate, a six-carbon molecule?


alpha-ketoglutarate

fumarate

oxaloacetate

succinate

Answer 1

Unfortunately, this is not something I can offer you a good explanation for... Rather, you just have to memorize it: the answer is oxaloacetate. You can apply a bit of logic: acetyl-CoA is a two carbon molecule, Citrate is a 6 carbon: thus, your molecule in question must be four carbons. Unfortunately for that approach, all of your answer choices are four carbon compounds.

See http://en.wikipedia.org/wiki/Citric_acid_cycle for a visual, which might help a bit more.

Answer 2

Which of these cellular metabolic processes occurs in all living things?


glycolysis

Krebs cycle

Electron Transport System


photosynthesis

Answer 3

Give this one a try - reason it out and let me know what you get!

Answer 4

photosynthesis

Answer 5

?

Answer 6

Do we undergo photosynthesis?

Answer 7

or glyco

Answer 8

something

Answer 9

krebs cycle

Answer 10

When an organism is in contact with oxygen, it generally undergoes aerobic respiration. This consists of glycolysis, Krebs Cycle, and the ETC (with oxygen acting as the electron acceptor).

Without oxygen, the latter two do not occur. Instead, alternative pathways are used...however, glycolysis is still the first step in those pathways.

Cna you figure it out from here?