11.3- THE LIGHT-INDEPENDENT REACTION

Question 1

Which products of LDR are used in the second stage of photosynthesis?

Answer 1

ATP and reduced NADP

Question 2

How are ATP and reduced NADP used in the second stage of photosynthesis?

Answer 2

to reduce glycerate 3-phosphate

Question 3

What does the second stage of photosynthesis not need unlike the first stage?

Answer 3

doesn’t require light directly and in theory occurs whether or not light available

Question 4

In practice, why would LIR need light?

Answer 4

requires products of LDR + so rapidly ceases when light absent

Question 5

Where does LIR happen?

Answer 5

in stroma of chloroplasts

Question 6

How does carbon dioxide enter? #1 Calvin cycle

Answer 6

CO2 from atmosphere diffuses into leaf through stomata + dissolves in water around walls of mesophyll cells, Then diffuses through cell-surface membrane, cytoplasm + chloroplast membranes into stroma of chloroplast

Question 7

What happens to the CO2 in the stroma? #2 Calvin cycle

Answer 7

CO2 reacts with 5-carbon compound- ribulose bisphosphate (RuBP) + reaction catalysed by enzyme called rubisco

Question 8

What does the reaction between CO2 + RuBP produce? #3 Calvin cycle

Answer 8

two molecules of 3-carbon glycerate 3-phosphate (GP)

Question 9

What is the reduced NADP from LDR used to do? #4 Calvin cycle

Answer 9

used to reduced glycerate 3-phosphate (GP) to triose phosphate (TP) using energy supplied by ATP

Question 10

What happens to the NADP after it has reduced GP into TP? #5 Calvin cycle

Answer 10

it’s re-formed + goes back to LDR to be reduced again by accepting more protons

Question 11

What happens to some triose phosphate (TP) #6 Calvin cycle

Answer 11

some converted to organic substances that plant requires such as starch, cellulose, lipids, glucose, amino acids + nucleotides

Question 12

What happens to most triose phosphate (TP) #7 Calvin cycle

Answer 12

most used to regenerate ribulose bisphosphate using ATP from LDR

Question 13

Where does LIR happen?

Answer 13

in stroma of chloroplast

Question 14

How is the chloroplast adapted to carry out LIR? (3)

Answer 14

fluid of stroma contains all enzymes needed to carry out LIR

stroma fluid surrounds grana

contains DNA + ribosomes

Question 15

How is the fluid of stroma containing all enzymes needed to carry out LIR an adaptation of chloroplasts for LIR?

Answer 15

stromal fluid is membrane-bound in chloroplast which means chemical environment which has high conc. of enzymes + substrates can be maintained within it- as distinct from environment of cytoplasm

Question 16

How is the stroma fluid surrounding the grana an adaptation of chloroplasts for LIR?

Answer 16

products of LDR in grana can readily diffuse into stroma

Question 17

How is the chloroplast containing both DNA + ribosomes an adaptation of chloroplasts for LIR?

Answer 17

so it can quickly + easily manufacture some of the proteins involved in LIR