B4

Question 1

What is photosynthesis?

Answer 1

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

Question 2

Where does photosynthesis take place?

Answer 2

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

Question 3

Is photosynthesis an endothermic or exothermic reaction and why?

Answer 3

Exothermic - energy is transferred from the environment to chloroplasts by light

Question 4

How can you show that a plant gives off oxygen during photosynthesis?

Answer 4

Using a water plant collect has bubbles produced during photosynthesis. The gas will relight a glowing splint as it contains oxygen

Question 5

Give examples of leaf adaptations which maximise the rate of photosynthesis?

Answer 5

Broad leaves - maximise surface area.
• Thin leaves - short diffusion distance.
• Chlorophyll present - trap light energy.
• Veins - transport water to leaves via xylem, remove photosynthesis products via phloem.
• Air spaces - allow CO, to enter and O, to leave.
• Guard cells - control opening of stomata for gaseous exchange and prevent water loss.

Question 6

What are the four main factors that affect the rate of photosynthesis?

Answer 6

Temp
Light intense
Carbon dioxide concentration
Amount if chlorophyll

Question 7

How does temp affect the rate of photosynthesis?

Answer 7

Increasing the temperature increases the rate of photosynthesis as the kinetic energy of particles is increased. The rate decreases past a certain temperature as enzymes become denatured.

Question 8

How does light intensity affect the rate of photosynthesis?

Answer 8

Increasing the light intensity increases the rate of photosynthesis until another factor becomes limiting

Question 9

How does carbon dioxide concentration affect the rate of photosynthesis

Answer 9

Increasing the carbon dioxide concentration increases the rate of photosynthesis as CO2 is required to make glucose

Question 10

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

Answer 10

Decreasing the amount decreases the rate as it’s requires to absorb light energy

Question 11

What’s a limiting factor?

Answer 11

An environmental factor which can restrict the rate of photosynthesis

Question 12

How can you calculate the rate of photosynthesis by measuring oxygen production?

Answer 12

Set up bubble potometer apparatus (pondweed in a sealed tube of water, attached to a capillary tube and a gas syringe).
• Oxygen gas produced causes the bubble in the capillary tube to move. The distance moved by the bubble is used to calculate the volume of oxygen produced.

Question 13

State 5 uses of the glucose produced during photosynthesis?

Answer 13

Respiration
Starch for storage
Cellulose for strength
Amino acid and protein synthesis
Lipids for energy storage in seeds

Question 14

What is aerobic respiration?

Answer 14

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

Question 15

What are the equations for aerobic respiration?

Answer 15

Glucose + oxygen —> carbon dioxide + water

Question 16

Where does aerobic respiration take place?

Answer 16

In the mitochondria

Question 17

Why do organisms require the energy released by respiration?

Answer 17

Synthesis of larger molecules
• Muscle contraction
• Maintenance of body temperature
• Active transport

Question 18

What is anaerobic respiration?

Answer 18

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

Question 19

What is the equation for anaerobic respiration?

Answer 19

Glucose —> lactic acid

Question 20

Why is anaerobic respiration less efficient than aerobic respiration?

Answer 20

Glucose in not completely broken down so less energy is transferred

Question 21

Why can anaerobic respiration lead to muscle fatigue?

Answer 21

Lactic acid builds up in the muscles preventing efficient contraction

Question 22

What is oxygen debt?

Answer 22

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

Question 23

What is fermentation?

Answer 23

A type of anaerobic respiration that occurs in yeast cells

Question 24

What is the equation for fermentation?

Answer 24

Glucose —> ethanol + carbon dioxide

Question 25

Why is fermentation reaction important?

Answer 25

It is used in the production of bread and alcoholic drinks

Question 26

What are the differences between aerobic and anaerobic respiration?

Answer 26

Aerobic requires oxygen; anaerobic does not

Aerobic produces CO2 and water ; anaerobic produces acetic acid or ethanol + CO2

Aerobic transfers a greater amount of energy

Question 27

How do muscles store glucose?

Answer 27

As glycogen

Question 28

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

Answer 28

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

Question 29

What is metabolism?

Answer 29

The sum of all the reaction that take place in a cell or an organism

Question 30

How do cells use the energy transferred by respiration?

Answer 30

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

Question 31

Give examples of metabolic reactions

Answer 31

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