Biology · AQA Paper 1
Photosynthesis
How plants make glucose by photosynthesis, what limits its rate, how to investigate the effect of light intensity, and what plants do with the glucose they make. It covers the equation, endothermic reactions, temperature, light intensity, carbon dioxide concentration and chlorophyll, and for Higher tier students the inverse square law and the economics of growing plants in greenhouses. Matches AQA GCSE Biology 4.4.1 (photosynthesis). Every lesson is for both Combined Science and separate Biology; the Higher tier extras are marked.
Lessons
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1
The Photosynthetic Reaction
Photosynthesis is the reaction that feeds almost every food chain on Earth. This lesson covers the equation for photosynthesis, why it is an endothermic…
8 terms -
2
Rate of Photosynthesis and Limiting Factors
A plant does not always photosynthesise as fast as it could. This lesson explains how temperature, light intensity, carbon dioxide concentration and…
8 terms -
3
Investigating Light Intensity and Photosynthesis
This is the required practical on photosynthesis. This lesson describes how to use pondweed to investigate the effect of light intensity on the rate of…
8 terms -
4
Uses of Glucose from Photosynthesis
Glucose is only the start. This lesson shows how a plant uses the glucose it makes: for respiration, and to make starch, fats and oils, cellulose and proteins…
8 terms
Key terms in this chapter
All 32, gathered from every lesson.
- Photosynthesis
- The reaction in which plants use light energy to make glucose and oxygen from carbon dioxide and water.
- Producer
- An organism that makes its own food, such as a plant.
- Chlorophyll
- The green pigment in chloroplasts that absorbs light for photosynthesis.
- Chloroplast
- The part of a plant cell where photosynthesis happens.
- Endothermic reaction
- A reaction that takes in energy from its surroundings.
- Reactant
- A substance that is used up in a chemical reaction.
- Product
- A substance made in a chemical reaction.
- Glucose
- A sugar made in photosynthesis, which is a source of energy.
- Limiting factor
- A factor that is in short supply and so limits the rate of a reaction.
- Light intensity
- How bright the light is.
- Carbon dioxide concentration
- The amount of carbon dioxide in the air around a plant.
- Optimum temperature
- The temperature at which the rate of reaction is greatest.
- Denatured
- Having a changed shape so an enzyme can no longer work.
- Rate of reaction
- How fast a reaction happens.
- Plateau
- A flat part of a graph, where the rate has stopped rising.
- Greenhouse
- A glass building used for growing plants in controlled conditions.
- Pondweed
- A water plant, such as Elodea or Cabomba, used in photosynthesis experiments.
- Independent variable
- The variable that the investigator changes.
- Dependent variable
- The variable that is measured.
- Control variable
- A variable that is kept the same so the test is fair.
- Sodium hydrogencarbonate
- A chemical added to water to provide carbon dioxide.
- Reliable
- Giving similar results each time the investigation is repeated.
- Inverse square law
- The rule that light intensity falls in proportion to 1 divided by the square of the distance.
- Mean
- An average, found by adding the values and dividing by how many there are.
- Starch
- An insoluble carbohydrate that plants use to store glucose.
- Insoluble
- Does not dissolve in water.
- Cellulose
- A carbohydrate that makes up plant cell walls.
- Amino acid
- A small molecule that is joined with others to make proteins.
- Protein
- A large molecule made of amino acids, used for growth and as enzymes.
- Nitrate ion
- A mineral ion that plants take from the soil, needed to make amino acids.
- Fat
- A lipid used for storage of energy.
- Tuber
- An underground part of a plant where food is stored.