photosynthesis

Question 1

limiting factor definition

Answer 1

any factor that directly affects a process, hence rate of reaction, if magnitude is changed

Question 2

limiting factors of photosynth

Answer 2

light intensity, co2 concentration, temperature

Question 3

major limiting factor?

Answer 3

co2 concentration

Question 4

how does temperature affect?

Answer 4

both light independent and dependent reactions are enzyme-controlled, so temperature can affect denaturation of enzymes

Question 5

other factors affecting photosynth

Answer 5

o2 concentration - acts as competitive inhibitor for rubisco when co2:o2 ratio is low

Question 6

how o2 affects calvin cycle

Answer 6

on bright hot days, stomata close up to restrict water loss. build up of o2 in leaf, oxygenase function of rubisco occurs

Question 7

light saturation point

Answer 7

point where light is no longer limiting factor (plateau starts)

Question 8

compensation point

Answer 8

light intensity at which rate of photosynthesis is equal to rate of respiration , net gaseous exchange is zero, no net sugars made

point where graph of o2 output against light intensity cuts x-axis

Question 9

absorption spectrum

Answer 9

record of amount of light absorbed by eahc pigment at each wavelength

Question 10

action spectrum

Answer 10

graph showing effectiveness of different wavelengths in stimulating photosynthesis

Question 11

why does action spectrum not match absorption spectrum of chlorophyll a exactly?

Answer 11

accessory pigments like chlorophyll b and carotenoids broaden the spectrum of wavelengths that can be absorbed for photosynthesis, and channel energy they absorb to special chlorophyll a

Question 12

function of thylakoid membrane in phosphorylation

Answer 12

• large surface area to embed many photosynthetic pigments to absorb light
• maintain sequential arrangement of electron carriers in etc
• maintain proton gradiant for atp synthesis
• hydrophobic core impermeable to protons allowing chemiosmosis