4.4 Photosynthesis

Question 1

Explain the shape of the graph at point A.

Answer 1

The rate of photosynthesis is increasing as temperature increases.

Becauses enzymes and substrates have more kinetic energy.

So there are more successful collisions.

Question 2

What is the main limiting factor of photosnthesis during winter.

Answer 2

Temperature

Question 3

What is the equation for photosynthesis?

Answer 3

Question 4

Explain the shape of the line at point B on the graph:

Answer 4

Photosynthesis is happening at its optimum rate.

Becauses enzymes and substrates have maximum kinetic energy.

So there are maximum possible successful collisions.

Question 5

DESCRIBE the graph below:

Answer 5

As temperature increases, rate of photosynthesis increases.

A maximum rate is reached.

Then the rate ogf photosynthesis decreases rapidly past the optimum temperature and stops at 45°C

Remember: you must include numbers from axis if they are given!!

Question 6

How do plants make Amino acids?

Answer 6

They combine glucose with nitrates.

Question 7

When using a lamp to look at how light intensity affects rate of photosynthesis, how can we increase the light intensity?

Answer 7

Move the lamp closer.

Question 8

What is the symbol for magnesium ions?

Answer 8

Mg²⁺

Question 9

Identify the limiting factor/s at point B

Explain how you know.

Answer 9

CO₂ conc/Temperature/Chlorophyll/Water

Because when light intensity increases past this point rate of photosynthesis does not - so must be one of the other factors.

Question 10

Identify the limiting factor at point A.

Explain how you know.

Answer 10

CO₂ concentration.

because as CO₂ concentration increases so does the rate of photosynthesis

Question 11

What is the symbol for nitrates?

Answer 11

NO₃^-

Question 12

What is meant by a limiting factor of photosynthesis?

Answer 12

Something that slows down the amount of photosynthesis that a plant can do.

Question 13

Which type of energy allows carbon dioxide and water to be converted into glucose and oxygen?

Answer 13

Light energy

Question 14

DESCRIBE the graph below…

Answer 14

As light intensity is increases rate of photosynthesis increases.

Eventually, the rate of photosynthesis remains constant.

Remember: if numbers are on the axis’ you mst include them in your description!!

Question 15

Where do plants get nitrates?

Answer 15

From the soil

Question 16

Why do plants need magnesium ions from soil?

Answer 16

to make chlorophyll

Question 17

What is the symbol equation for photosynthesis?

Answer 17

Question 18

Identify the limiting factor at point A.

Explain how you know.

Answer 18

Amount of light

because as light intensity increases so does the rate of photosynthesis

Question 19

Identify the limiting factor/s at point B.

Explain how you know.

Answer 19

Light Intensity/Temperature/Chlorophyll/Water

Because when CO₂ concentration increases past this point rate of photosynthesis does not - so must be one of the other factors.

Question 20

What is the main limiting factor of photosynthesis on a Summer day? Explain your answer.

Answer 20

CO₂ concentration.

Because it is generally warmer in Summer.

Because there is a higher light intensity in Summer.

Atmospheric CO₂ is low (0.03%).

Question 21

Explain the shape of the graph at point C.

Answer 21

The rate of photosnthesis is decreasing rapidy past the optimum temperature.

Because enzymes are denaturing.

Change to shape of active site.

Fewer successful collisions.

Question 22

What 5 things do plants use glucose for?

Answer 22

1. Oils - energy store
2. Starch - energy store
3. Cellulose - for cell walls
4. Amino acids - for growth and repair
5. Respiration - for energy

OSCAR (wil help you remember!)

Question 23

DESCRIBE the graph below:

Answer 23

As CO₂ concentration is increases rate of photosynthesis increases.

Eventually, the rate of photosynthesis remains constant.

Remember: if numbers are on the axis’ you mst include them in your description!!

Question 24

A plant tha is lacking magnesium will show what symptoms?

Answer 24

Yellow leaves as less chlorophyll.

Poor growth as less photosynthesis happening.

Question 25

What is the main limiting factor of photosynthesis at night time?

Answer 25

The amount of light

Question 26

Starch is insoluble in the cytoplasm of plant cells. Why is this a useful property?

Answer 26

It does not increase the concentration of cytoplasm.

So water does not move into the cell via osmosis which would cause the cell to swell up.

Question 27

What are the limiting factors of photosynthesis?

Answer 27

1. Light
2. CO₂ concentration.
3. Temperature
4. Amount of chlorophyll
5. Water availability

Question 28

As you move a plant away from a lamp, the light intensity reaching the plant decreases. We say that distance and light intensity are i__________ p_____________.

Answer 28

inversely proportional

Question 29

How can we calculate the light intensity coming from a lamp that is reaching a plant?

Answer 29

The Inverse Square Law

Light intensity = 1 ÷ Distance of plant from lamp²

Question 30

How do farmers optimise conditions for photosynthesis?

Answer 30

The grow crops in a greenhouse.

Question 31

How do greenhouses optimise photosynthesis?

Answer 31

1. Artificial lighting allows photosynthesis to occur at night.
2. Shades - can be shut if it gets too warm.
3. Propane burner - releases CO₂
4. Maintain optimum temp for photosnyhtesis.
5. Glass allows light to reach crops.
6. Fertilisers can be used to supply minerals e.g. magnesium

Question 32

A lamp is 30cm from some pond weed. What is the light intensity?

Answer 32

Light intensity = 1 ÷ Distance of plant from lamp²

1/30² = 0.001

Question 33

A lamp is 10cm away from some pond weed. What is the light intensity?

Answer 33

Light intensity = 1 ÷ Distance of plant from lamp²

1/10² = 0.01

Question 34

A lamp is 20cm away from some pond weed. What is the light intensity?

Answer 34

Light intensity = 1 ÷ Distance of plant from lamp²

1/20² = 0.0025

Question 35

The light intensity of a lamp is 0.0001. How far from the pond weed is the lamp?

Answer 35

Light intensity = 1 ÷ Distance of plant from lamp² is rearranged to:

Distance of plant from lamp = √(1/light intensity)

Therefore:

√(1/0.0001) = 100 cm away