Topic 4 - Bioenergetics

Question 1

What does photosynthesis do?

Answer 1

Uses energy to change carbon dioxide and water to glucose and oxygen, the glucose is food for the plant and the oxygen is a waste product

Question 2

Give the photosynthesis equation

Answer 2

CO2 + H2O –> O2 + C6H12O6

Question 3

What are the five main ways that glucose is used in a plant?

Answer 3

1. Respiration
2. Making cellulose
3. Making amino acids
4. Stored as oils and fats
5. Stored as starch

Question 4

What are the limiting factors of photosynthesis?

Answer 4

1. Light intensity - the higher the light intensity the faster the rate of photosynthesis
2. Carbon dioxide - too little carbon dioxide slows dow the rate of photosynthesis
3. Temperature - the temperature has to be just right in order for the enzymes involved to work the most effectively

Question 5

What are limiting factors?

Answer 5

These are factors that affect the rate of photosynthesis, any of these can have a single do combined affect on .e.g. chlorophyll

Question 6

How can you do an experiment to measure the rate of photosynthesis?

Answer 6

Put pondweed in a test tube and attach a needle through a bung - you can use a lamp, the temperature and the amount of CO2 you inject to measure the affect of limiting factors

Question 7

What is the equation of light intensity?

Answer 7

Light intensity (‘proportional to’) 1/distance^2

Question 8

What is the inverse square law mean?

Answer 8

The inverse square law means that if you halve the distance the light intensity will be four time greater

Question 9

How does photosynthesis help farmers?

Answer 9

Knowing what conditions are required for plant growth can enable farmers to create these artificially .e.g. greenhouses

Question 10

How do greenhouses improve photosynthesis?

Answer 10

They allow light through whilst acting as thermal insulators to ensure that temperature does not become a limiting factor, greenhouses can also supply artificial light or CO2 to plants and being enclosed protects them from diseases

Question 11

Define respiration (remember to use scientific terminology)

Answer 11

Respiration is the process of transferring energy from glucose, which goes into every cell

Question 12

T/F: respiration is endothermic

Answer 12

False: it is exothermic because it transfers energy to the environment (the cell)

Question 13

List three ways the energy from respiration is used within the body

Answer 13

1. Build larger molecules .e.g. protein synthesis
2. Allows muscles to contract
3. Used to regulate body temperature (only in mammals and birds)

Question 14

Define metabolism

Answer 14

The sum of all chemical reactions within an organism

Question 15

Name some reaction where larger molecules are made from smaller ones

Answer 15

1. Lipids are made from glycerol and fatty acids
   2a. Glucose is combined with nitrate ions to make amino acids
   2b. Amino acids join together to make proteins
2. Small glucose molecules join together to form starch

Question 16

Name some reactions where larger molecules are broken down into smaller ones

Answer 16

1. Glucose is broken down in respiration
2. Excess protein is broken down to for urea
3. During digestion enzymes break down molecules

Question 17

What is the difference between aerobic and anaerobic respiration?

Answer 17

Anaerobic respiration occurs when there is not enough oxygen

Question 18

Where does aerobic respiration occur?

Answer 18

Mitochondria

Question 19

Where does anaerobic respiration occur?

Answer 19

Cytoplasm

Question 20

Why is aerobic respiration more effective?

Answer 20

It transfers more energy to the cell and anaerobic respiration produces lactic acid which leads to cramps

Question 21

What is the word equation for aerobic respiration?

Answer 21

Glucose + Oxygen –> Carbon Dioxide + Water + (Energy)

Question 22

Describe anaerobic respiration in a simple sentence

Answer 22

The incomplete breakdown of glucose to produce lactic acid due to a lack of oxygen

Question 23

What is the word equation for anaerobic respiration in plants and yeast cells?

Answer 23

Glucose –> Ethanol + Carbon Dioxide

Question 24

How can we use anaerobic respiration in food production?

Answer 24

1. Bread - CO2 from anaerobic respiration in yeast makes the bread rise
2. Beer and wine - ethanol from anaerobic respiration in yeast produces alcohol

Question 25

Why do you respire more when you exercise?

Answer 25

Your muscles need more energy to move

Question 26

What is oxygen debt?

Answer 26

The amount of extra oxygen you have which needs to react with lactic acid in order to form CO2 and H2O

Question 27

T/F: Oxygen debt is the reason your breathing and heart rate remain high even after you’ve finished exercising

Answer 27

True