B4: Bioenergetics

Question 1

What is photosynthesis and where does it take place?

Answer 1

Photosynthesis uses energy to change carbon dioxide and water into glucose and oxygen. It takes place in the chloroplasts in green plant cells, which contain pigments like chlorophyll that absorb light. It is endothermic.

Question 2

What is the word equation for photosynthesis?

Answer 2

Carbon dioxide + water -> glucose + oxygen

Question 3

What is the symbol equation for photosynthesis?

Answer 3

6CO2 + 6H2O -> c6H12O6 + 6O2

Question 4

What are the five main ways in which plants use glucose?

Answer 4

Respiration
Making cellulose
Making amino acids
Storing as lipids
Storing as starch

Question 5

What are the limiting factors that affect the rate of photosynthesis?

Answer 5

Light intensity
Carbon dioxide concentration
Temperature

Question 6

What is an equation for the rate of photosynthesis?

Answer 6

Light intensity is proportional to 1 divided by the distance squared.

Question 7

How can you artificially create the ideal conditions for farming?

Answer 7

Greenhouse - trap suns heats

Extra light

Increased carbon dioxide levels - e.g. Paraffin heater

Keeping plants enclosed to avoid pests and disease.

Question 8

Define respiration.

Answer 8

Respiration is the process of transferring energy from glucose. It happens in every cell in your body continuously. All living things respire. Respiration is exothermic.

Question 9

Give three examples of how organisms use the energy transferred by respiration.

Answer 9

1. To build larger molecules from smaller ones (like proteins from amino acids)
2. In animals it’s used to allow the muscles to contract.
3. In mammals and birds the energy is used to keep their body temperature steady in colder surroundings.

Question 10

Describe the difference between aerobic and anaerobic respiration.

Answer 10

Aerobic respiration requires oxygen to make energy, when not enough oxygen is supplied (for example when exercising) then anaerobic respiration must take place. This occurs without oxygen but also produces lactic acid and leads to an oxygen debt that has to be paid off.

Question 11

What is the word equation for aerobic respiration?

Answer 11

Glucose + oxygen -> carbon dioxide + water

REMEMBER: the equation for respiration is simply the equation for photosynthesis in reverse

Question 12

What is the symbol equation of aerobic respiration?

Answer 12

C6H12O6 + 6O2 -> 6CO2 + 6H2O

Question 13

What is the word equation for anaerobic respiration?

Answer 13

Glucose -> lactic acid

Question 14

What is the word equation for anaerobic respiration in plants and yeast cells (and what is it also called)?

Answer 14

Glucose -> ethanol + carbon dioxide

This is fermentation - how beer and also bread is made.