Photosynthesis pt3

Question 1

What happens during the carbon fixation (Calvin cycle) reactions of photosynthesis?

Answer 1

ATP & energized electrons (NADH) are used to make a 3-carbon sugar phosphate (PGAL) from carbon dioxide.

Question 1

Where do the carbon fixation reactions occur in a chloroplast?

Answer 1

In the chloroplast stroma

Question 2

The enzyme that ‘fixes’ or captures CO2 in the carbon fixation reactions is called ___.

Answer 2

All of the RUBP names are correct

Question 3

The prime end-product of photosynthesis is ____.

Answer 3

the 3-carbon sugar-phosphate PGAL

Question 4

What human activities are causing atmospheric CO2 to increase and global climate change?

Answer 4

Both fossil fuel consumption and deforestation

Question 5

What may happen, especially when CO2 is low and O2 is high as when stomata close during the day to conserve water?

Answer 5

RuBisCO may catalyze a reaction between RuBP and oxygen rather than CO2 and photorespiration occurs.

Question 6

Following photorespiration, what organelles in the affected cells are responsible for salvaging the resulting glycolate (at the loss of carbon, ATP & NADPH) to the amino acid serine and then bringing it back to the carbon fixation reactions?

Answer 6

chloroplast, peroxisome,, and mitochodrion.

Question 7

How do adapted plants essentially eliminate photorespiration?

Answer 7

C4 photosynthesis

Question 8

What is true about the Hatch-Slack Pathway?

Answer 8

the initial carbon fixing enzyme is PEP carboxylase is very efficient an capturing CO2.

Phosphenol pyruvate combines with CO2 to form oxaloacetate and then malate.

CO2 is removed from malate and used to permanently fix carbon by combining with RuBP in the presence of RUBISCO.

The process expends more energy per PGAL produced than if the carbon fixation reactions (C3) occur alone without it.

all of these options except the ‘none’ option are true

Question 9

in C4 plants

Answer 9

there is spatial division of labor: ordinary mesophyll cells efficiently obtain CO2 by the Hatch-slack pathway and bundle sheath cells use the resulting malate to fix carbon and make PGAL.

Question 10

in CAM plants

Answer 10

There is temporal separation: cells obtain CO2 by the Hatch-slack pathway at night and use the resulting malate to fix carbon and make PGAL during the next day while stomata are closed to save water

Question 11

Opuntia species prickly pear cacti

Answer 11

All of these options are correct