LIGHT INDEPENDENT REACTIONS

Question 1

What occurs in a light independent reaction? (1)

Answer 1

in these reactions, carbon dioxide is converted to carbohydrates.

Question 2

where do light independent reactions occur? (1)

Answer 2

occur in the stroma of chloroplasts surrounding the grana.

Question 3

what is the Calvin cycle? (1)

Answer 3

carbon dioxide readily diffuses into sugars in a cyclic process

Question 4

what is a summary of the Calvin cycle? (1)

Answer 4

Co2 is combined with an acceptor molecule in the presence of a special enzyme (ribose bio phosphate carboxylase) - the stroma is packed full of rubisco which easily makes up the bulk of the protein in a green plant.

Question 5

what are the stages of the Calvin cycle? (3)

Answer 5

Carbon fixation, reduction and regeneration

Question 6

what occurs in carbon fixation? (1)

Answer 6

the acceptor molecule is a sugar called ribulose bio phosphate and CO2 are added in a process called carbon fixation by the catalyse of the enzyme rubisco. the product is a compound called glycerate - 3 - phosphate.

Question 7

what occurs in carbon reduction? (1)

Answer 7

glycerate - 3 - phosphate is reduced to form a compound called glyceraldhyde - 3 - phosphate ( some of this leaves the cycle in order to make the cycle stable once more)

Question 8

what occurs in carbon regeneration? (1)

Answer 8

glyceraldhyde - 3 - phosphate is converted into ribulose bio phosphate once more

Question 9

what happens with the remainder of the glyceraldhyde - 3 - phosphate? (1)

Answer 9

the reminder is converted into carbohydrate products of photosynthesis mainly glucose and starch or serves as intermediates that are starting points for all metabolites that plant requires.

Question 10

what are intermediates? (1)

Answer 10

all the substances of a metabolic pathway from which the end products are assembled.

Question 11

what else is glucose used for? (1)

Answer 11

glucose is also the substrate for respiration, the intermediates for respiration are also starting points for the synthesis of other metabolites.

Question 12

what is a limiting factor? (1)

Answer 12

in any process controlled by more than one factor then the rate of the overall process will be determined by the availability of the least favourable factor.

Question 13

what factors effect photosynthesis? (3)

Answer 13

light intensity, carbon dioxide and temperature