Topic 4-Bioenergetics

Question 1

What role do chloroplasts and chlorophyll play in photosynthesis?

Answer 1

Chloroplasts contains chlorophyll which absorbs light needed for photosynthesis.

Question 2

What type of reaction is photosynthesis?

Answer 2

Endothermic, energy is transferred from the environment in the process.

Question 3

What is the photosynthetic word equation?

Answer 3

Carbon + Water = Glucose + Oxygen

Dioxide

Question 4

What 5 main ways is glucose used in plants?

Answer 4

1. Respiration- covert the rest of glucose into useful substances.
2. Making cellulose- make cell walls strong.
3. Making amino acids- made into proteins.
4. Stored as oils and fats- turned into lipids for storing in seeds.
5. Stored as starch- stored in roots, stems and leaves. Ready to use in photosynthesis when it’s winter or dark. Starch is insoluble, makes it better for storing glucose. Cells with lots of glucose draw in water and swell up.

Question 5

Name 3 factors that limit the rate of photosynthesis.

Answer 5

Light intensity
Carbon dioxide levels
Temp.

Question 6

How is the rate of photosynthesis affected?

Answer 6

All 3 limiting factors work together, so if one factor is limited the rate of photosynthesis becomes limited.
At night- light limits it
In winter- temp. limits it
If it’s warm and bright enough- carbon dioxide levels are limited

Question 7

How can chlorophyll be a limiting factor of the rate of photosynthesis?

Answer 7

Amount of chlorophyll can be affected by disease or environmental stress. These can mean chloroplasts become damaged or to not make enough chlorophyll.
This means the rate is reduced as not as much light needed for photosynthesis can be absorbed.

Question 8

Why does temp. affect the rate of photosynthesis?

Answer 8

Temp. too low= enzymes needed for photosynthesis work slowly at low temps.
Temp. too hot= enzymes needed for photosynthesis become denatured (shape of active site is changed). This happens about 45 degrees.

Question 9

What is the law between light intensity and distance?

Answer 9

Light is directly proportional to 1
Intensity ——-
distance x distance

Question 10

How do greenhouses make perfect conditions for farming?

Answer 10

Trap the suns heat, make sure temp. doesn’t become a limiting factor.
Artificial light- so photosynthesis can happen when it’s dark.
Paraffin heater- produces more carbon dioxide
Keeping greenhouse enclosed- keep pests and pathogens out.
Add fertilisers- provide minerals that are needed.

Question 11

What is respiration?

Answer 11

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

Question 12

What respires?

Answer 12

All living things.

Question 13

What type of reaction is respiration?

Answer 13

Exothermic- transfers energy into the environment.

Question 14

How does organisms use energy produced in respiration?

Answer 14

1. Build up larger molecules from smaller ones (proteins from amino acids)
2. Muscles to contract
3. Keep body temp. steady in cold conditions

Question 15

What is metabolism?

Answer 15

Metabolism is all the chemical reactions happening in an organism.

Question 16

What happens in some reactions?

Answer 16

Larger molecules are made from smaller ones. E.g. lipids are each made up of one glycerol molecule and 3 fatty acids.
Larger molecules can be broken down into smaller ones. E.g. excess protein is broken down in a reaction to produce urea, urea is then excreted in urine.

Question 17

What is the word equation for aerobic respiration?

Answer 17

Glucose + oxygen = carbon + water

dioxide

Question 18

What is the word equation for anaerobic respiration?

Answer 18

Glucose = lactic acid + little energy

Question 19

What releases the most energy, aerobic of anaerobic respiration?

Answer 19

Aerobic respiration

Question 20

What is the word equation for fermentation (anaerobic respiration in a yeast cell)?

Answer 20

Glucose = ethanol + carbon dioxide

Question 21

What is fermentation used for?

Answer 21

In the food and drink industry as it makes bread and alcoholic drinks.

Question 22

Why do you respire more during exercise?

Answer 22

Muscles need more energy to contract as they contract more frequently.
Your cells need more oxygen in them.
Breathing rate and breath volume increase to get more oxygen in the blood. Heart rate increases to get more oxygenated blood around the body faster.
When sprinting anaerobic exercise occurs as your cells can’t respire quick enough.
Anaerobic respiration leads to lactic acid build up in the muscles.
Long periods of exercise result in muscle fatigue.

Question 23

How does anaerobic respiration lead to oxygen debt?

Answer 23

After anaerobic exercise you’ll experience oxygen debt.
Oxygen debt= amount of extra oxygen your body needs to react with the build up of lactic acid and remove it from cells.
You breathe harder after exercise so more oxygen is put into your body.
The pulse and breathing rate stay high whilst lactic acid and carbon dioxide levels are high.
The blood that enters your muscles transports the lactic acid to the liver, where the lactic acid is converted back to glucose.