Topic 4 - Photosynthesis

What type of reaction is Photosynthesis?

Endothermic

What does endothermic mean?

Means energy is transferred from the environment in the process

Where does photosynthesis take place?

In chloroplasts

What absorbs the light in chloroplasts?

A green pigment called chlorophyll

What is the word equation for photosynthesis?

What is the balanced symbol equation for photosynthesis?

What are the 5 uses of glucose in plants?

1. C - Cellulose - glucose is converted into cellulose for making strong plant cell walls

2. R - Respiration - transfers energy from glucose, enables plants to convert glucose into other useful substances.

3. O - Oils/fats - glucose is turned into lipids for storing in seeds

4. P - Proteins - Glucose is combined with nitrate ions to make amino acids.

5. S - Starch - Glucose is turned into starch and stored in roots, stems and leaves.

When might a plant use starch?

Ready for when photosynthesis isn’t happening, like in winter

What is the advantage of using starch to store glucose

Starch is insoluble - a cell with lots of glucose would draw lots of water and swell up

What is meant by a limiting factor in photosynthesis?

A factor that limits the rate of photosynthesis

What are the limiting factors for the rate of photosynthesis?

1. Intensity of light

2. Concentration of carbon dioxide

3. Temperature

4. Water available

5. Amount of chlorophyll

How can the amount of chlorophyll be affected?

1. Diseases

2. Environmental stress (lack of nutrients)

Describe how the light intensity affects the rate of photosynthesis?

As the light level is raised, the rate of photosynthesis increases steadily, but only until a certain point - when the light intensity is no longer the limiting factor, as shown by the flat line.

Describe how the % level of carbon dioxide affects the rate of photosynthesis?

As the % level of carbon dioxide increases, the rate of photosynthesis increases steadily - but only until a certain point when the carbon dioxide is not the limiting factor anymore - as shown by the flat line.

Describe how the temperature affects the rate of photosynthesis

Since photosynthesis uses enzymes, if the temperature is too low, enzymes work slower. As the temperature increases, the rate of photosynthesis increases steadily, until it reaches the optimum temperature. After the optimum temp, the rate of photosynthesis rapidly decreases as the enzymes are destroyed in too hot conditions.

1. What is the independent variable (change) of the measuring the rate of photosynthesis practical

2. What is the dependent variable (measure)

3. What is the control variable

1. Light intensity - power of lamp/distance between light and plant

2. Rate of photosynthesis - time/number of bubbles/volume of oxygen

3. Temp/pond weed (length or species)/power of lamp/sodium hydrogencarbonate solution

USE PMT FLASHCARDS FOR R.P 6

What is the inverse square law?

What might a farmer use in the winter for a greenhouse?

A paraffin heater - heats the greenhouse and makes carbon dioxide as a by - product

What might a farmer use in the summer for a greenhouse?

Use shades and ventilation

What might farmers use in the night/winter?

Artificial light

What is an advantage of using a green house?

Prevents diseases and pests.