Explain what might happen if the third step of the Calvin cycle did not occur.?

Answer 1

I assume you have the Holt, Rinehart and Winston worksheets.

So your question was :

'If the RuBP consumed in Step 1 was not regenerated in Step 4 of the Calvin Cycle, then,

a. CO2 would stop diffusing into the stroma.

b. the cycle would speed up because of an increase in CO2 molecules.

c. the plant cell would lack G3P molecules.

d. the plant cell would stop bonding carbon atoms from CO2 into organic compounds

The two you can immediately cross out are A and B because diffusion of CO2 has nothing to do with RuBP. As for B, the cycle would not speed up. If anything, it would slow down or stop.

Now, we are left with:

c. the plant cell would lack G3P molecules.

d. the plant cell would stop bonding carbon atoms from CO2 into organic compounds

The article you read on the front sheet [I will not copy that down] never specified much on whether or not the cell would stop bonding carbon atoms from CO2 into organic compounds, so I personally settled for C. My reasoning behind this is that G3P is made from RuBP, and without it, the cell, like the answer states would lack G3P.

TL;DR the answer is 'D'

I do hope this helped. Good luck with Bio!

Edit: answer is D

Answer 2

I happen :)