photosynthesis

Question 1

limiting factors of photosynthesis

Answer 1

1. light intensity
2. carbon dioxide concentration
3. temperature

Question 2

relationship between light and photosynthesis

Answer 2

• increased light intensity —> increase rate of photosynthesis until light saturation point is reached

Question 3

relationship between CO2 concentration and photosynthesis

Answer 3

increased CO2 concentration —> increase rate of photosynthesis

Question 4

why does an increase in CO2 concentration increase the rate of photosynthesis?

Answer 4

• more CO2 can combine with RUBP during carbon fixation
• more GP produced —> triose phosphate —> organic compounds

Question 5

relationship between temperature and photosynthesis

Answer 5

• increase in temperature —> increase in rate of photosynthesis
• photosynthesis works best at its optimum temperature

Question 6

The light-dependent reaction of photosynthesis is temperature-
indifferent.

On the other hand, the light-independent reaction (Calvin Cycle) is
temperature-sensitive.

Why is this so?

Answer 6

light dependent reaction: driven mainly by light energy and physical processes
calvin cycle: relies on enzyme-controlled reactions

Question 7

absorption spectrum

Answer 7

a graph that shows the absorbance of different wavelengths of light by a particular pigment

Question 8

action spectrum

Answer 8

a graph that shows the rate of photosynthesis at different wavelengths of light

Question 9

absorption spectrum for chlorophyl and carotenoids

Answer 9

chlorophyl: violet- blue and red-orange
carotenoids: violet and blue-green

Question 10

why does the graph of chlorophyl peak in the violet-blue and red-orange areas?

Answer 10

• absorb light most effectively in those areas
• green only reflected

Question 11

maximum photosynthesis rate at action spectrum

Answer 11

blue and red light

Question 12

why does photosynthesis peak at blue and red light

Answer 12

• chlorophyll absorbs light most effectively
• provides greatest amount of energy for light-dependent reactions

Question 13

2 stages of photosynthesis

Answer 13

1. light-dependent reaction
2. light-independent reaction (calvin cycle)

Question 14

main purpose of light-dependent reaction

Answer 14

solar energy —> chemical energy

Question 15

site of light-dependent reaction

Answer 15

thylakoid membrane (grana)

Question 16

site of calvin cycle

Answer 16

stroma

Question 17

type of phosphorylation is light-dependent reactions

Answer 17

1. non cyclic
2. cyclic

Question 18

non cyclic electron flow

Answer 18

primary pathway of energy transformations in light-dependent reaction (photosystem 1+2)

Question 19

cyclic electron flow

Answer 19

excited electrons take an alternative path
- only ps 1
- only ATP produced

Question 20

photosystem

Answer 20

collections of photosynthetic pigments that absorb light energy and transfer the energy onto electrons

Question 21

what is produced in light reaction

Answer 21

NADPH + ATP + O2 (by-product)

Question 22

photolysis

Answer 22

chemical process in which water molecules are broken down into smaller units through the absorption of light