Topic 4 - Bioenergetics

Question 1

What is the word equation for photosynthesis?

Answer 1

carbon dioxide + water –>
glucose +oxygen
(in the prescence of light)

Question 2

What is the symbol equation for photosynthesis?

Answer 2

6CO2 + 6H2O → C6H12O6 + 6O2

Question 3

How do plants use glucose?

Answer 3

• Cellulose (making it)
• Respiration
• Oils and fats
• Protein
• Starch

Question 4

What do plants use to make amino acids?

Answer 4

glucose and nitrate ions

Question 5

What can plants store glucose as?

Answer 5

• lipids (in seeds)
• starch (roots, stems, seeds and leaves)

Question 6

What are limmiting factors on photosynthesis?

Answer 6

• Light
• Carbon dioxide level
• Temperature

Question 9

Describe how light intensity effects the rate of photosynthesis in a plant (and as shown on a graph)

Answer 9

• As light intensity increases, so does the rate of photosynthesis.
• At a certain point the graph plateaus as the rate of photosynthesis is no longer increasing.
• This is because either the temperature or CO2 is the limiting factor and not light.

Question 10

Describe the effect of temperature on the rate of photosynthesis in a plant (and as shown on a graph)

Answer 10

• Enzymes needed for photosynthesis will work slower at lower temperatures
• As the temperature gets hotter, the rate of photosynthesis will increase until the optimum temperature is reached
• After this point, enzymes begin to denature and are destroyed (45°C)

Question 10

Describe how the carbon dioxide level effects the rate of photosynthesis in a plant (and as shown on a graph)

Answer 10

• As carbon dioxide levels increase, so does the rate of photosynthesis.
• At a certain point the graph plateaus as the rate of photosynthesis is no longer increasing.
• This is because either the temperature or light intensity is the limiting factor and not the carbon dioxide level.

Question 11

what is the inverse square law?

Answer 11

light intensity is inversely proportional to the distance squared.

Question 12

How can greenhouses help in creating a better environment to grow plants in?

Answer 12

1. Temperature- trap the sun’s heat and make sure that the temperature isn’t limiting
2. Light- always needed for photosynthesis so farmers might use artificial light after the sun goes down to give their plants more quality photosynthesis time
3. CO2 levels- using a paraffin heater for example since it heats the greenhouse while giving off CO2 as a by-product
4. General health of plants- easier to keep free from pests and diseases, can fertilise soil too, less damage if bad weather (e.g. frost)

Question 13

What are the costs of a greenhouse- why is it important the farmer knows optimum conditions for their plants?

Answer 13

• Controlling conditions in a greenhouse cost money but can result in better yield of crop and more frequent harvest.
• It is important the farmer supplies just the right amount of heat, light etc. otherwise it could end up simply being a waste of money.