Photosynthesis

Question 1

Why do plants need energy?

Answer 1

biological processes such as photosyntehsis, active transport, DNA replication, cell division and protein synthesis.

Question 2

“Plants produce ATP in their chloroplasts during photosynthesis. They also produce
ATP during respiration. Explain why it is important for plants to produce ATP during
respiration in addition to during photosynthesis.”

Answer 2

1. In the dark there is no ATP 
production in 
photosynthesis.
2. Some tissues may be unable to 
photosynthesise and produce 
ATP.
3. ATP cannot be stored.
4. Plant uses more ATP than they 
produce, in photosynthesis;
5. ATP is needed for active transport.

Question 3

What is photophosphorylation?

Answer 3

Adding phosphate to a molecule using light energy.

Question 4

Thylakoids () are stacked up in the chloroplast intro structures called…

Answer 4

GRANA. (singular = granum)

Question 5

Where does the light dependent reaction take place?

Answer 5

thylakoid membranes.

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Question 6

“Describe the light dependent reaction.”

Answer 6

1 Light (energy) excites/raises energy level of electrons in
chlorophyll;
2 Electrons pass down electron transfer chain;
3 passage involves redox reactions;
5 Energy released / carriers at decreasing energy levels;
6 ATP generated from ADP and inorganic phosphate.

Question 7

Where does the light Independent reaction take place?

Answer 7

in the stroma of the chloroplast.

Question 8

“In the light-independent reaction of photosynthesis, the carbon in carbon dioxide
becomes carbon in triose phosphate. Describe how.”

Answer 8

1. Carbon dioxide combines with ribulose
   bisphosphate/RuBP;
2. To produce two molecules of glycerate 3-phosphate/GP;
3. the GP is then Reduced to triose phosphate/TP;
   4.ATP and REDUCED NADP are required for the reduction of GP to triose phosphate.

Question 9

“During photosynthesis, oil-palm trees convert carbon dioxide into organic substances.
Describe how.”

Answer 9

1. Carbon dioxide combines with ribulose
   bisphosphate/RuBP this Produces two molecules of glycerate (3-)phosphate/GP;
2. the GP is then Reduced to triose phosphate/TP;
   2.ATP and REDUCED NADP are required for the reduction of GP to triose phosphate.
3. Triose phosphate converted to other organic substances e.g. glucose.
4. In the light independent reaction/Calvin cycle;

Question 10

Optimum conditions for photosynthesis?

Answer 10

1. High light intensity of a certain wavelength.
2. Optimum temperature (usually 25c). (if temp is too low, enzymes become inactive, if temp is too high, enzymes denature- at high temps, stomata close to avoid losing too much water, so photosynthesis slows down as less CO2 enters leaf when stomata are closed).
3. Carbon dioxide at 0.4%

Question 11

The rate of CO2 production was higher when the apple slices were in nitrogen than when they were in air explain why

Answer 11

Respiring anaerobically

(Anaerobic respiration/respiration with nitrogen) less efficient/produces less ATP;

More anaerobic respiration/ more glucose/substrate must be respired to produce same amount of ATP (so more carbon dioxide produced

Question 12

Graph shows 3 species of plant species X has a higher rate of photosynthesis and high light intensity

species X is the first tree to become established in succession use the graph to explain why

Answer 12

Vegetation consists mainly of low growing species/herbs/annuals/ 3max no/few tress;

Species X has high rate of photosynthesis at high light intensity; Species X grow fastest at high rate of photosynthesis / at high light

outcompete other species

Question 13

Light dependant location

Answer 13

thylakoids

Question 14

Light independent location

Answer 14

stroma

Question 15

Law of limiting factors

Answer 15

At any given moment, the rate of physiological process is limited by the factor with the least favourable value