Topic 4 Rate of photosynthesis +

Question 1

Why can light intensity only increase the rate of photosynthesis up to a certain point

Answer 1

Because either the temperature or the co2 level will now be a limiting factor

Question 2

How can you change the light intensity in a lab

Answer 2

Moving a lamp closer to or further away from the plant

Question 3

To get a smooth graph of light intensity against rate of photosynthesis you must measure light intensity using

Answer 3

A light meter or do maths with your results from distance of lamp from the plant

Question 4

When the line on the graph with the percentage of co2 against rate of photosynthesis flattens out what does this mean

Answer 4

CO2 is no longer a limiting factors but light or temperature needs to be increased

Question 5

What happens if the temperature of the plant is too low

Answer 5

The enzymes needed for photosynthesis work more slowly

Question 6

What happens if the temperature of a pant gets too hot

Answer 6

The enzymes become denatured and no longer work

Question 7

What temperature does it become too hot for plants

Answer 7

Around 45°C

Question 8

What plant is used to measure the effect of light intensity on the rate of photosynthesis

Answer 8

Canadian pond weed

Question 9

What does the rate the pondweed produces oxygen correspond to

Answer 9

The rate at which it is photosynthesising

Question 10

Steps 1-3 of rate of photosynthesis experiment

Answer 10

1) White light is placed at specific distance from the pond weed
2) pondweed is left for a set amount of time and as photosynthesis occurs oxygen will collect in the capillary tube
3) at the end the syringe is used to draw the gas bubble in the tube alongside a ruler to measure the length of the gas bubble which is proportional to the volume of O2 produced

Question 11

What are the control variables of the rate of photosynthesis experiment

Answer 11

Temperature and time the pond weed is left for

Question 12

How can the effect of temperature or co2 be measured

Answer 12

Pondweed put in a water bath at a set temperature
Measured amount of sodium hydrogencarbonate can be dissolved in water
Should be repeated at different temps or with different concentrations of sodium hydrogencarbonate

Question 13

As distances increases between the light and plant

Answer 13

Light intensity decreases therefore they are inversely proportional
Light intensity = 1/distance^2

Question 14

What is the most common way to create an ideal environment for plants to grow

Answer 14

A greenhouse

Question 15

How do greenhouses stop the temperature from becoming limiting

Answer 15

Trap in the suns heat

Question 16

What is used in a green house if it becomes too warm or too hot

Answer 16

Shades and ventilation are used if it becomes too warm
Heaters are used if it becomes too cold

Question 17

What can be used to allow plants to have more photosynthesis time whilst it is dark

Answer 17

Artificial light

Question 18

How can farmers increase the level of co2

Answer 18

Using paraffin heaters that produce co2 as a byproduct

Question 19

What does keeping plants enclosed in a greenhouse make it easier to keep them from

Answer 19

Pests and diseases

Question 20

Why do farmers add fertilisers to the soil

Answer 20

To provide the plants with all the minerals they need for healthy growth

Question 21

How do the farmers make back money from suppling all these conditions

Answer 21

Crops grow much faster and more decent so can make more money selling them