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Photosynthesis and respiration flash cards

Flash cards on photosynthesis and respiration: word and symbol equations, chloroplasts, mitochondria, limiting factors, aerobic and anaerobic respiration and fermentation.

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The cards, front and back

1
Front
Word equation for photosynthesis
Back
Carbon dioxide + water → glucose + oxygen, using energy from light absorbed by chlorophyll.
2
Front
Balanced symbol equation for photosynthesis
Back
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
3
Front
Where does photosynthesis take place?
Back
In the chloroplasts, mostly in the leaf cells of green plants and in algae.
4
Front
What does chlorophyll do?
Back
It is a green pigment in chloroplasts that absorbs light energy, which is used to make glucose.
5
Front
Is photosynthesis endothermic or exothermic?
Back
Endothermic. Energy from light is transferred to the chemical store of glucose.
6
Front
What is a limiting factor?
Back
The factor in shortest supply that stops the rate of photosynthesis going any higher. The main ones are light intensity, carbon dioxide concentration and temperature.
7
Front
Why does photosynthesis slow down at very high temperatures?
Back
The enzymes that control the reactions become denatured, so they no longer work.
8
Front
Name four ways a plant uses the glucose it makes.
Back
Respiration; making starch for storage; making cellulose for cell walls; making amino acids (with nitrate ions) for proteins. It is also used to make fats and oils for storage.
9
Front
How do carbon dioxide and oxygen get in and out of a leaf?
Back
By diffusion through tiny pores called stomata, mostly on the underside of the leaf. Guard cells open and close the stomata.
10
Front
How do you test a leaf for starch?
Back
Boil it in water, soak it in ethanol to remove the chlorophyll, rinse it, then add iodine solution. It turns blue-black where starch is present.
11
Front
What is respiration?
Back
A series of chemical reactions in every living cell that releases energy from glucose. It is not the same as breathing.
12
Front
Word equation for aerobic respiration
Back
Glucose + oxygen → carbon dioxide + water, releasing energy.
13
Front
Balanced symbol equation for aerobic respiration
Back
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O
14
Front
Where does aerobic respiration mainly happen?
Back
In the mitochondria.
15
Front
Is respiration endothermic or exothermic?
Back
Exothermic. It transfers energy to the surroundings and to processes in the cell.
16
Front
Word equation for anaerobic respiration in muscles
Back
Glucose → lactic acid, releasing a small amount of energy. It happens when muscles cannot get enough oxygen.
17
Front
Word equation for anaerobic respiration in yeast and plant cells
Back
Glucose → ethanol + carbon dioxide. In yeast this is called fermentation and is used to make bread and alcoholic drinks.
18
Front
Compare aerobic and anaerobic respiration.
Back
Aerobic needs oxygen and releases much more energy per glucose molecule. Anaerobic needs no oxygen, releases much less energy and makes lactic acid (animals) or ethanol and carbon dioxide (yeast and plants).
19
Front
What is oxygen debt?
Back
The extra oxygen needed after exercise to break down the lactic acid built up in the muscles during anaerobic respiration.
20
Front
What is ATP?
Back
The molecule cells use to carry energy. Respiration releases energy from glucose and stores it in ATP, which the cell uses for processes such as muscle contraction and active transport.
21
Front
How are photosynthesis and respiration linked?
Back
The products of one are the reactants of the other: photosynthesis uses carbon dioxide and water to make glucose and oxygen, and aerobic respiration uses glucose and oxygen to make carbon dioxide and water.

How to use this template

This deck covers the two big energy processes in biology. You will learn the word and balanced symbol equations for photosynthesis and aerobic respiration, where each happens, limiting factors, how plants use glucose, how gases move through stomata, the starch test, anaerobic respiration in muscles and yeast, oxygen debt and a simple idea of ATP. It suits GCSE and IGCSE biology or combined science, Year 10 and Year 11 science, high school biology and AP or IB courses as a quick refresher before the detailed biochemistry. Use Learn mode to get the equations right, then Test mode, and let spaced repetition bring back the comparison cards. Print it double-sided to quiz a friend.

Tips

Write the two word equations next to each other. Seeing that one is roughly the reverse of the other makes both easier to remember.
Balance the symbol equations yourself on paper each time, counting carbon, hydrogen and oxygen atoms, rather than memorising them as a string.
For limiting factor graphs, practise saying which factor is limiting on the rising part of the curve and what might be limiting where it levels off.
Never write that respiration makes energy. Energy is released or transferred, and examiners do not accept made.
Learn the products of anaerobic respiration as two separate facts: lactic acid in animals, ethanol and carbon dioxide in yeast and plants.

Make it fit

If your course goes further, add cards on the light-dependent reactions, the Calvin cycle, glycolysis and the Krebs cycle.
Add a card for the required practical on light intensity and pondweed, with the method and the variables.
Make reverse cards with the equation on the front and the name of the process on the back.
Split the deck into a photosynthesis set and a respiration set if you are learning them in different weeks.

Updated October 28, 2026

The cards, front and back

How to use this template

Tips

Make it fit

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