Photosynthesis

A reaction in which plants use light energy to make glucose from carbon dioxide and water.

Carbon dioxide + water, in light, makes glucose + oxygen.

6CO₂ + 6H₂O makes C₆H₁₂O₆ + 6O₂ (in light).

Carbon dioxide and water.

Glucose and oxygen.

It takes in energy from the environment, transferred by light.

In the chloroplasts.

It absorbs the light energy for photosynthesis.

By diffusion through the stomata.

It is taken up by the roots and carried up in the xylem.

In the glucose that is made.

An organism that makes its own food, such as a plant.

Kill and decolourise it, then add iodine solution, which turns blue-black.

To remove the chlorophyll, so the colour change can be seen.

Oxygen.

Name the substance marked X and say where it goes.

Oxygen. It is a product of photosynthesis and leaves the leaf through the stomata.

Label everything that goes into and comes out of the leaf.

Light energy, carbon dioxide and water go in. Oxygen and glucose come out. Photosynthesis happens in the chloroplast.

A factor in short supply that sets the rate of a reaction.

Temperature, light intensity, carbon dioxide concentration and the amount of chlorophyll.

Light provides the energy for the reaction.

It is a reactant, so more is available.

The enzymes are denatured.

Another factor is now limiting.

The factor on the x axis is limiting.

The plant makes less chlorophyll, so absorbs less light.

Amount of product or reactant ÷ time.

A flat part of a graph where the rate stops changing.

Any one of them might be the limiting factor.

To raise the light intensity when it is limiting.

To raise the rate when carbon dioxide is limiting.

If temperature is not the limiting factor, the rate does not increase.

Whether the extra crop is worth more than the cost of adding heat, light or carbon dioxide.

Describe the shape of each graph and say what is limiting.

Light and carbon dioxide: the rate rises then levels off, and another factor is limiting on the flat part. Temperature: it rises to an optimum, then falls because enzymes are denatured.

Oxygen.

The distance of the lamp from the pondweed.

The number of bubbles per minute, or the volume of gas collected.

To provide carbon dioxide, so it is not the limiting factor.

To stop the temperature rising and affecting the rate.

Any three of the same pondweed, temperature, carbon dioxide level, time and size of beaker.

To check reliability and calculate a mean.

The bubbles can differ in size.

Collect it in a gas syringe or measuring tube and measure the volume.

It decreases.

The further away the lamp is, the dimmer the light that reaches the plant.

Light intensity is proportional to 1 ÷ distance².

It falls to one quarter.

It falls to one ninth.

A straight line, while light is the limiting factor.

Name the part marked X and say why it is there.

The ruler. It measures the distance between the lamp and the pondweed, which is the independent variable.

Label the apparatus.

Lamp, ruler, pondweed, bubbles of oxygen, beaker of water with sodium hydrogencarbonate and thermometer.

Respiration, starch, fats and oils, cellulose, and amino acids for proteins.

To release energy for the plant's life processes.

Starch is insoluble, so it does not affect osmosis, and it stores a lot in a small space.

To strengthen the cell walls.

They are a store of energy for the young plant.

Glucose and nitrate ions.

They are absorbed from the soil.

Amino acids.

Add iodine solution. It turns blue-black.

Add Benedict's reagent and heat. It turns green, yellow, orange or brick red.

Add Biuret reagent. It turns purple.

Orange-brown to blue-black.

To provide nitrate ions for plants to make proteins.

In roots, tubers, seeds and fruits.

In the phloem.

Name the use of glucose marked X and say what it does.

Cellulose. It is made from glucose and strengthens the plant's cell walls.

Name the five uses of glucose.

Respiration (energy), starch (insoluble store), fats and oils (stored in seeds), cellulose (cell walls) and amino acids for proteins (with nitrate ions).