2.14 - Rates of Photosynthesis

Question 1

What are rates of photosynthesis usually measured in?

Answer 1

rate of net CO2 uptake
or
rate of O2 production

Question 2

True or False:
In a plant cell, photosynthesis and cellular respiration happen simutaniously

Answer 2

True

Question 3

What three things affect photosynthesis?

Answer 3

Temperature, CO2 levels, and light intensity

Question 4

What is the optimal temperature range for photosynthesis?
What happens if the 2 extremes are reached?

Answer 4

Ideal Temp: In between too cold and too hot
Too cold: not enough kinetic energy
Too hot: enzymes denature (structure changes, therefore, looses function)

Question 5

What happens when the Calvin Cycle becomes saturated?

Answer 5

CO2 levels increase untill ALL rubisco enzymes are occupied.
In a graph, the line would plateau/ flatten out

Question 6

What happens when CO2 levels decrease in the Calvin Cycle?

Answer 6

It’ll slow down until it stops.
It can decrease further until the rate of photosynthesis becomes negative. This means that it’ll consume O2 instead of producing it. This may be caused by either photorespiration or by the rate of photosynthesis falling below the rate of cellular respiration.

Question 7

What is photorespiration?

Answer 7

Rubisco fixes O2 to RuBP instead of CO2; waste of ATP

Question 8

What is “dark respiration rate”?

Answer 8

When there is no light, photosynthesis stops, and the plant releases CO2 & consumes O2. It used cellular respiration to produce ATP

Question 9

True or False:
The Calvin Cycle needs light for it to work

Answer 9

Both!
While it can function without the direct light rays, it still needs light to fuel it, as the light reactions produce products that take part in the cycle. Without those products, the Calvin Cycle does not work

Question 10

What is the light compensation point?

Light inensity and photosynthesis

Answer 10

As light increases:
photosynthesis = cellular respiration
No net release or uptake of CO2

Question 11

What is the light limited range?

Light inensity and photosynthesis

Answer 11

As light continues to increases:
photosynthesis > cellular respiration

Question 12

What is the light saturation?

Light inensity and photosynthesis

Answer 12

As light intensity peaks:
photosynthesis&raquo_space;> cellular respiration
[top of graph flattens out]