Plants And Photosynthesis

Front 1

State the equation for photosynthesis.

Back 1

Carbon dioxide + water ---> glucose + oxygen

Above the arrow: sunlight

Below the arrow: chlorophyll

Front 2

What is photosynthesis?

Back 2

The process by which plants are able to use sunlight energy to convert CO2 into glucose (food).

Front 3

Inside which organelle does photosynthesis happen?

Back 3

The chloroplasts.

Front 4

What is the substance found inside chloroplasts that is essential for photosynthesis?

Back 4

Chlorophyll.

Front 5

Where does photosynthesis happen in green plants?

Back 5

In the leaves.

Front 6

Name three tissues or organs present in plant leaves.

Back 6

1) Mesophyll tissue: where most of the photosynthesis occurs

2) Xylem and phloem: they transport things like water, mineral ions and sucrose around the plant.

3) Epidermal tissue: covers the whole plant.

Front 7

What is the rate of photosynthesis affected by?

Back 7

The intensity of light, the volume of CO2 and the temperature.

Water is also needed for photosynthesis, but if a plant is so short of water that it becomes the limiting factor in photosynthesis, this is the least of its problems!

Front 8

What does the term 'limiting factor' mean?

Back 8

The factor (thing) that is stopping photosynthesis from happening any faster.

(At night, light is the limiting factor; in Winter, it's often the temperature.)

Front 9

Describe what's happening in the graph.

Back 9

1) Light provides the energy needed for photosynthesis.

2) As the light intensity increases, so does the rate of photosynthesis - but only to a certain point.

3) The rate of photosynthesis stops increasing because either the temperature or the CO2 level are the limiting factors.

Front 10

Describe what's happening in the graph.

Back 10

1) CO2 is one of the raw materials needed for photosynthesis.

2) As the amount of CO2 increases, so does the rate of photosynthesis - but only to a certain point.

3) The rate of photosynthesis stops increasing because either the temperature or the light intensity are the limiting factors.

Front 11

Describe what's happening in the graph.

Back 11

1) If temperature's the limiting factor, it's usually because it's too low - the enzymes needed for photosynthesis work slowly at low temperatures.

2) But if the plant gets too hot, the enzymes will become denatured.

3) This happens at about 45 degrees Celsius - the enzymes no longer work, so photosynthesis does not occur.

Front 12

How does using a greenhouse create the ideal environment for plants to grow in? (Think: photosynthesis)

Back 12

By increasing the rate of photosynthesis. A greenhouse traps the sun's heat, which makes sure that the temperature doesn't become limiting.

A farmer can also increase the level of carbon dioxide. A paraffin heater can be used to do this - as the paraffin burns, it makes carbon dioxide as a by-product.

Front 13

Name another way that a greenhouse creates the ideal environment for plants to grow in.

Back 13

Keeping the plants enclosed in a greenhouse makes it easier to keep them free from pests and disease.

The farmer can also add fertilisers to the soil to provide all the minerals needed for healthy growth.

Front 14

Name the 5 ways that plants use glucose (produced during photosynthesis).

Back 14

1) For respiration

2) Making cell walls

3) Making proteins

4) Stored in seeds

5) Stored as starch

Front 15

Describe how glucose is used in respiration.

Back 15

1) Plants manufacture glucose in their leaves.

2) They then use some of the glucose for respiration.

3) This releases energy which enables them to convert the rest of the glucose into various other substances, which they can use to build new cells and grow.

4) To produce some of these substances they also need to gather a few minerals from the soil.

Front 16

Describe how glucose is used in making cell walls.

Back 16

Glucose is converted into cellulose for making strong cell walls, especially in a rapidly growing plant.

Front 17

Describe how glucose is used in making proteins.

Back 17

Glucose is combined with nitrate ions (absorbed from the soil) to make amino acids, which are then made into proteins.

Front 18

Describe how glucose is used when storing it in seeds.

Back 18

Glucose is turned into lipids (fats and oils) for storing in seeds. Sunflower seeds, for examples, contain a lot of oil. Seeds also store starch.

Front 19

Describe how glucose is used when it is stored as starch.

Back 19

Glucose is turned into starch and stored in roots, stems and leaves, ready for use when photosynthesis isn't happening (like in Winter).

Starch is insoluble (doesn't dissolve in water) which makes it better for storing than glucose - a cell with lots of glucose in would absorb lots of water and swell up.