Bioenergetics

Question 1

What is photosynthesis?

Answer 1

The process by which plants synthesise glucose glucose using light energy from the sun which is converted into chemical energy.

Question 2

Where does photosynthesis take place?

Answer 2

Within chloroplasts in leaf palisade cells. They contain chlorophyll a green pigment which absorbs light energy.

Question 3

Word equation for photosynthesis?

Answer 3

Carbon Dioxide + Water –> Glucose + Oxygen

Question 4

Symbol equation for photosynthesis?

Answer 4

6CO2 + 6H2O –> C6H12O6 + 6O2

Question 5

What kind of reaction is photosynthesis?

Answer 5

Endothermic reactions - energy is transferred from the environment to chloroplasts by light.

Question 6

5 leaf adaptations that maximise the rate of photosynthesis?

Answer 6

Broad leaves - maximise surface area.
Thin leaves - short diffusion distance.
Chlorophyll - traps light energy
Air spaces - allow CO2 to enter and O2 to leave
Guard Cells - control the opening of stomata for gas exchange to prevent water loss.

Question 7

4 main factors that affect the rate of photosynthesis?

Answer 7

Light intensity
Carbon Dioxide concentration
Temperature
Amount of chlorophyll

Question 8

How does temperature affect the rate of photosynthesis?

Answer 8

Increasing temp = Increased rate of photosynthesis as the kinetic energy of the particles is increased. The rate decreases part a certain temperature as the enzymes denature.

Question 9

How does light intensity affect the rate of photosynthesis?

Answer 9

Increasing light intensity = increase rate of photosynthesis until another factor becomes limiting.

Question 10

How does carbon dioxide concentration affect the rate of photosynthesis?

Answer 10

Increasing CO2 = Increased rate of photosynthesis until another factor becomes limiting as carbon dioxide is required to make glucose.

Question 11

How does the amount of chlorophyll affect the rate of photosynthesis?

Answer 11

Decreasing the amount of chlorophyll decreases the rate of photosynthesis as chlorophyll is required to absorb light energy.

Question 12

What is a limiting factor?

Answer 12

An environmental factor which can restrict the rate of photosynthesis.

Question 13

State the law that the describes the relationship between the distance of a light source from a plant and light intensity?

Answer 13

Inverse Law
Light intensity = 1/d^2

Question 14

5 uses of the glucose produced during photosynthesis?

Answer 14

Respiration
Produce fat or oil for storage
Cellulose to strengthen the cell wall
Produce amino acids for protein synthesis
Converted into insoluble starch for storage

Question 15

What is aerobic respiration?

Answer 15

An exothermic reaction in which glucose reacts with oxygen to release energy which can be used by cells.

Question 16

Word equation for aerobic respiration?

Answer 16

Glucose + Oxygen –> Carbon Dioxide + Water

Question 17

Symbol equation for aerobic respiration?

Answer 17

C6H12O6 + 6O2 –> 6CO2 + 6H20

Question 18

Where does aerobic respiration occur?

Answer 18

Mitochondria

Question 19

Why do organisms need the energy released by respiration?

Answer 19

Active transport
Muscle contraction
Maintaining body temperature
Synthesis of large molecules

Question 20

What is anaerobic respiration?

Answer 20

An exothermic reaction in which glucose is broken down to release energy in the absence of oxygen.

Question 21

Equation for anaerobic respiration?

Answer 21

Glucose –> Lactic Acid

Question 22

Why is anaerobic respiration less efficient than aerobic?

Answer 22

Glucose is not completely broken down so less energy is transferred.

Question 23

Why can anaerobic respiration lead to muscle fatigue?

Answer 23

Lactic acid (product of anaerobic respiration) builds up in muscles which prevents efficient contraction.

Question 24

What is oxygen debt?

Answer 24

The amount of oxygen needed to convert lactic acid back into glucose after anaerobic respiration.

Question 25

What is fermentation?

Answer 25

A type of anaerobic respiration that occurs in yeast cells.

Question 26

Equation for fermentation?

Answer 26

Glucose –> Ethanol + Carbon Dioxide

Question 27

Why is the fermentation reaction important?

Answer 27

It is used in the production of bread and alcoholic drinks.

Question 28

Difference between aerobic and anaerobic respiration?

Answer 28

Aerobic respiration requires energy whereas anaerobic respiration doesn’t.
Aerobic produces carbon dioxide and water whereas anaerobic produces lactic acid or ethanol + carbon dioxide.
Aerobic respiration transfers a greater amount of energy.

Question 29

How do muscles store glucose?

Answer 29

As glycogen

Question 30

What changes take place when muscular activity increases in the body?

Answer 30

Heart rate increases and arteries dilate which increases the flow of oxygenated blood to muscles.
Stored glycogen is converted back into glucose.
Breathing rate increases - increases the rate of gas exchange

Question 31

How is lactic acid transported away from the muscles?

Answer 31

Blood flow through the muscles transports lactic acid to the liver where it is oxidised back into glucose.

Question 32

What is metabolism?

Answer 32

The sum of all the reactions that take place in a cell or organism.

Question 33

How do cells use the energy transferred by respiration?

Answer 33

To continuously carry out enzyme-controlled processes which lead to the synthesis of new molecules.

Question 34

6 examples of metabolic reactions?

Answer 34

Respiration
Photosynthesis
Breakdown of excess proteins into urea
Glucose into starch/glycogen/cellulose
Glycerol and fatty acids into lipids.
Glucose and nitrate ions into amino acids