What is glucose used for in photosynthesis

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The glucose produced in photosynthesis may be:
- Used for respiration (both aerobic and anaerobic)
- Converted into insoluble starch for storage in the stems, leaves and roots
- Used to produce fat or oil for storage (especially in seeds)
- Used to produce cellulose, which strengthens the cell wall
- Combined with nitrate ions absorbed from the soil to produce amino acids for protein synthesis

The fate of glucose

A test to show that a plant is photosynthesising is to test the leaf for the presence of starch using iodine
This can be used to show the effect of light on photosynthesis

Starch testing of leaves shows that photosynthesis has been taking place

Remember that plants always respire to release energy – but they only photosynthesise during the day if conditions are right.

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Photosynthesis is essential for the majority of all food chains on Earth, so learning the equation above is essential!

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State where a land-based plant would obtain the reactants of photosynthesis named in part (a).

Figure 2 shows a plant cell with three cellular components labelled.

Identify which of the following options gives the correct name and function of P, Q and R.

	P	Q	R
A	Chloroplast - stores water	Cytoplasm - where chemical reactions take place	Vacuole - stores water
B	Vacuole - the site of photosynthesis	Chloroplast - stores water	Cytoplasm - where chemical reactions take place
C	Vacuole - stores water	Cytoplasm - where the chemical reactions take place	Chloroplast - the site of photosynthesis
D	Chloroplast - the site of photosynthesis	Cytoplasm - where chemical reactions take place	Vacuole - stores water

Factors that Affect Photosynthesis

Global warming means there are lots of floods and so there is plenty of water.
If water availability is low, plants close their stomata to stop transpiration, meaning that photosynthesis is limited by carbon dioxide.
Water cannot be measured using a measuring cylinder.
Water is not needed for photosynthesis, only for respiration.

Factors that Affect Photosynthesis

Interactions of Limiting Factors
Factors that Affect Photosynthesis

Investigating Photosynthesis

The student evaluated his method and decided that counting bubbles is an inaccurate way of measuring the rate of photosynthesis for two reasons.

Suggest a more accurate method which could be used to collect information about the amount of oxygen gas produced as the aquatic plant photosynthesizes.

[1 mark]

Investigating Photosynthesis

Glucose produced in photosynthesis has been stored as starch in the leaf
The plant has been carrying out transpiration so the leaves lack starch
Starch has been made in the leaf during the process of respiration
Glucose is stored as starch to be used protein synthesis

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State where a land-based plant would obtain the reactants of photosynthesis named in part (a).

Figure 2 shows a plant cell with three cellular components labelled.

Identify which of the following options gives the correct name and function of P, Q and R.

	P	Q	R
A	Chloroplast - stores water	Cytoplasm - where chemical reactions take place	Vacuole - stores water
B	Vacuole - the site of photosynthesis	Chloroplast - stores water	Cytoplasm - where chemical reactions take place
C	Vacuole - stores water	Cytoplasm - where the chemical reactions take place	Chloroplast - the site of photosynthesis
D	Chloroplast - the site of photosynthesis	Cytoplasm - where chemical reactions take place	Vacuole - stores water

Factors that Affect Photosynthesis

Global warming means there are lots of floods and so there is plenty of water.
If water availability is low, plants close their stomata to stop transpiration, meaning that photosynthesis is limited by carbon dioxide.
Water cannot be measured using a measuring cylinder.
Water is not needed for photosynthesis, only for respiration.

Factors that Affect Photosynthesis

Interactions of Limiting Factors
Factors that Affect Photosynthesis

Investigating Photosynthesis

The student evaluated his method and decided that counting bubbles is an inaccurate way of measuring the rate of photosynthesis for two reasons.

Suggest a more accurate method which could be used to collect information about the amount of oxygen gas produced as the aquatic plant photosynthesizes.

[1 mark]

Investigating Photosynthesis