B8 - Photosynthesis

Question 1

What is the word equation for photosynthesis?

Answer 1

Carbon dioxide + water (+light)&raquo_space;> glucose + oxygen

Question 2

What is the balanced chemical symbol equation for photosynthesis?

Answer 2

6CO2 + 6H2O&raquo_space;> C6H12O6 + 6O2

Question 3

Is photosynthesis an endo- or exothermic reaction?

Answer 3

Endothermic

Question 4

What energy transfer occurs in photosynthesis?

Answer 4

Light energy to chemical energy

Question 5

Where does photosynthesis occur in a plant cell?

Answer 5

Chloroplasts

Question 6

What pigment are chloroplasts filled with?

Answer 6

Chlorophyll

Question 7

What is the function of chlorophyll?

Answer 7

Captures light energy

Question 8

What are the four factors which affect the rate of photosynthesis?

Answer 8

Temperature, light intensity, carbon dioxide concentration, amount of chlorophyll

Question 9

Why does increasing light intensity increase the rate of photosynthesis?

Answer 9

Light provides the energy the plants need to photosynthesise

Question 10

Why does increasing temperature increase the rate of photosynthesis?

Answer 10

A higher temperature increases the rate of the chemical reactions

Question 11

Why does increasing the temperature too far stop photosynthesis?

Answer 11

The enzymes in the plant become denatured and stop working

Question 12

Why does increasing the concentration of carbon dioxide increase the rate of photosynthesis?

Answer 12

Carbon dioxide is a raw material that is needed for photosynthesis

Question 13

How can we investigate the effect of light intensity on the rate of photosynthesis?

Answer 13

1. Place pondweed in a test tube with water
2. Place a light source 10cm away from it
3. Turn light source on a measure the number of bubbles produced in 1 min
4. Move the light source back to 20cm and repeat
5. Repeat until there is a big enough range of results to see a pattern

Question 14

What can be done to stop temperature affecting the rate of photosynthesis?

Answer 14

Use an LED light, or place the boiling tube into a beaker of water

Question 15

What is the inverse square law?

Answer 15

light intensity ( oc symbol) 1/d2

Question 16

How does the inverse square law apply to photosynthesis?

Answer 16

The intensity of light is inversely proportional to the square of the distance from the light source.

Question 17

What does the inverse square law mean in practice when considering how plants grow?

Answer 17

When the light is moved twice as far from the plant it will receive a quarter of the energy

Question 18

Why can’t a commercial grower of plants just increase all three limiting factors of PHS to maximum levels to obtain optimum growth?

Answer 18

Light, temperature and CO2 all cost money to supply

– a balance between expenditure and income must be struck for a profit to be made.

Question 19

Name three ways glucose produced in photosynthesis is used in plants.

Answer 19

• Respiration
• Converted into insoluble starch for storage
• To produce fat or oil for storage
• To produce cellulose, which strengthens the cell wall
• To produce amino acids for protein synthesis.

Question 20

What else, other than glucose, do plants need to produce proteins?

Answer 20

Nitrate ions

Question 21

Where are mineral ions absorbed from and through which plant organ?

Answer 21

From the soil, through the roots.