B1.4 Photosynthesis Flashcards
What is photosynthesis?
A chemical reaction that happens in the chloroplasts of plant cells. It produces glucose for use by the plant, and oxygen as a waste product.
What is the word equation for photosynthesis?
Carbon dioxide + water –> glucose + oxygen
light energy and chlorophyll should go over/below the arrow
What is chlorophyll?
A green pigment found in the chloroplasts that absorbs light energy (it is therefore necessary for photosynthesis to happen)
During what parts of the day is the rate of photosynthesis equal to the rate of respiration in plants?
Early morning/late evening
Van Helmont grew a willow tree in a weighed amount of soil. After five years, he discovered that the willow tree weighed about 74 kg more than it did at the start. yet the weight of the soil had hardly changed, what did he conclude?
Van Helmont concluded that plant growth cannot only be due to minerals from the soil. He thought that the extra plant material had come from the water alone.
What insoluble substances can glucose be converted into?
oils, fats and starch
What are the advantages of using insoluble substances such as starch for storage, rather than soluble substances such as glucose?
They do not affect the water concentration inside cells
They do not move away from the storage areas in the plant
Glucose can be converted into cellulose, what do plants use cellulose for?
To make cell walls.
Plants can convert glucose into protein, what do plants use protein for?
Proteins for growth and repair
to make hormones and enzymes
What three factors can limit the speed of photosynthesis?
- light intensity, carbon dioxide concentration and temperature.
Photosynthesis is a process with two main stages, what are these stages?
- Light energy is used to split water, releasing oxygen gas and hydrogen ions
- Carbon dioxide gas combines with the hydrogen to make glucose
Describe the effect of increasing carbon dioxide concentration on the rate of photosynthesis.
Increasing carbon dioxide concentration initially increases the rate of photosynthesis, however after a certain point it has no effect, the rate of photosynthesis plateaus.
