Bioenergetics

Question 1

State the balanced symbol equation for photosynthesis

Answer 1

6 CO₂ + 6 H₂O → C₆H₁₂O₆ + 6 O₂

Question 2

State the word equation for photosynthesis

Answer 2

light

carbon dioxide + water → glucose + oxygen

Question 3

Name 5 uses of glucose (for plants)

Answer 3

• Respiration
• Making Cellulose
• Making Amino Acids
• Stored as Oils or Fats
• Stored as Starch

Question 4

How glucose is used for respiration (in plants)?

Answer 4

Respiration transfers energy from glucose = enables plant to convert rest of glucose into other useful substances

Question 5

How glucose is used to make cellulose (in plants)?

Answer 5

Glucose is converted into cellulose for making strong plant cell walls

Question 6

How glucose is stored as oils or fats (in plants)?

Answer 6

Glucose is turned to lipids (fats & oils) for storing in seed

Question 7

How glucose is used to make amino acids (in plants)?

Answer 7

Glucose combined with nitrate ions (from soil) to make amino acids = made then into proteins

Question 8

Where is starch stored and why is it stored?

Answer 8

Glucose turned into starch and stored in roots, stems & leaves, ready for use when photosynthesis isn’t happening (like in winter)

Question 9

Why is starch better for storing than glucose?

Answer 9

Because starch is insoluble - cell with lots of glucose would draw in loads of water and swell up

Question 10

What is a limiting factor?

Answer 10

Is something that can stop photosynthesis from happening any

Question 11

Name 4 things the rate of photosynthesis is affected by?

Answer 11

• Temperature
• Intensity of light
• Concentration of carbon dioxide
• Chlorophyll

Question 12

How can amount of chlorophyll in plant be affected?

Answer 12

Can be affect by disease or environmental stress (lack of nutrients)

Question 13

How does amount of chlorophyll affect the rate of photosynthesis?

Answer 13

If chloroplasts are damaged or don’t make enough chlorophyll (e.g. due to disease), means rate of photosynthesis decreases as they can’t absorb as much light

Question 14

In winter, what is usually the limiting factor?

Answer 14

Temperature

Question 15

At night, what is usually the limiting factor?

Answer 15

Light

Question 16

When it’s warm enough and bright enough, what is usually the limiting factor?

Answer 16

Carbon dioxide

Question 17

Why does photosynthesis require light?

Answer 17

Because it provides energy

Question 18

As the light level is raised, what happens to the rate of photosynthesis?

Answer 18

It increases steadily BUT only up to a certain point

Question 19

Why might the rate of photosynthesis not increase as the light intensity increases?

Answer 19

Because either temperature or CO2 level is a limiting factor

Question 20

As the CO2 level is raised, what happens to the rate of photosynthesis?

Answer 20

It increases steadily BUT only up to a certain point

Question 21

Why does the temperature affect the rate of photosynthesis?

Answer 21

Because it affects enzymes involved

Question 22

What does it mean if the limiting factor is temperature?

Answer 22

Means the temperature is too low

Question 23

Why does increasing the temperature make the rate of photosynthesis increases?

Answer 23

Because the collisions between enzymes and substrates occur more frequently

Question 24

What happens to the rate of photosynthesis when a plant gets too hot and why?

Answer 24

Enzymes become denatured causing photosynthesis to stop completely

Question 25

Why is respiration important?

Answer 25

It transfers energy that cells needs to do everything - this energy is used for all living processes

Question 26

What is respiration?

Answer 26

Process of transferring energy from glucose, which goes on in every cell

Question 27

Name 3 things respiration transfers energy for?

Answer 27

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

Question 28

What is aerobic respiration?

Answer 28

Respiration using oxygen - most efficient way to transfer energy from glucose

Question 29

State the word equation for aerobic respiration

Answer 29

glucose + oxygen → carbon dioxide + water

Question 30

State balanced symbol equation for aerobic respiration

Answer 30

C₆H₁₂O₆ + 6 O₂ → 6 CO₂ + 6 H₂O

Question 31

When is anaerobic respiration is used?

Answer 31

If there's not enough oxygen

Question 32

Why doesn't anaerobic reposition transfer nearly as much energy as aerobic respiration?

Answer 32

Because glucose isn't fully oxidised (doesn't combine with oxygen)

Question 33

What is anaerobic respiration?

Answer 33

It's the incomplete breakdown of glucose, making lactic acid

Question 34

State the word equation for anaerobic respiration (occurs in animals)

Answer 34

glucose → lactic acid

Question 35

When is anaerobic respiration useful?

Answer 35

Only useful in emergencies

Question 36

When plants and yeast cells respire without oxygen, what do they produce?

Answer 36

They produce ethanol and carbon dioxide (instead of lactic acid)

Question 37

What is anaerobic respiration called in yeast cells?

Answer 37

fermentation

Question 38

In bread-making, what makes bread rise?

Answer 38

The carbon dioxide from fermentation

Question 39

In beer and wine-making, what produces alcohol?

Answer 39

The fermentation process

Question 40

State the word equation for anaerobic respiration that occurs in plants and yeast cells

Answer 40

glucose → ethanol + carbon dioxide

Question 41

Why do muscles need energy from respiration?

Answer 41

To contact

Question 42

Name 3 things that happens when you exercise (to increase respiration)

Answer 42

* Breathing rate increases * Breath volume increase * Heart rate increases

Question 43

Why does your breathing rate and breath volume increases when you exercise?

Answer 43

To get more oxygen into blood

Question 44

Why does your heart rate increases when you exercise?

Answer 44

To get this oxygenated blood around body faster & also removes CO2 more quickly at same time

Question 45

When you do really vigorous exercise (e.g. Sprinting), what happens?

Answer 45

Your body can't supply oxygen to your muscles quickly enough so they start respiring anaerobically

Question 46

Why anaerobic respiration not the best way transfer energy from glucose?

Answer 46

Because lactic acid builds up in muscles which gets painful

Question 47

After resorting to anaerobic respiration, when you stop exercising you'll have an ...

Answer 47

"oxygen debt"`

Question 48

What is an oxygen debt?

Answer 48

Amount of extra oxygen your body needs to react with build up lactic acid and remove it from cells

Question 49

When oxygen reacts with lactic acid, what is formed?

Answer 49

(Harmless) CO2 and water

Question 50

Why do you have to keep breathing hard for a while after you stop exercising?

Answer 50

To get more oxygen into your blood (transported to muscle cells)

Question 51

When does your pulse and breathing rate stay high?

Answer 51

Whilst there's high levels of lactic acid and CO2

Question 52

What the other way your body copes with high levels of lactic acid?

Answer 52

Blood that enters your muscles transports lactic acid to liver. In liver, lactic acid is converted back to glucose.

Question 53

How can you increase carbon dioxide levels in a greenhouse?

Answer 53

Using paraffin heater = heats & makes CO2 as by-product

Question 54

What's the benefit of keeping plants in a greenhouse?

Answer 54

Keep free from pests & diseases

Question 55

Why does a fitter person have a lower heart rate?

Answer 55

A fitter person's heart is stronger → can pump more blood in each beat = doesn't have to work as hard

Question 56

Name 2 short-term internal effects of exercise

Answer 56

* Glucagon turns glycogen back into glucose for respiration * Vasodilation

Question 57

Define heart rate

Answer 57

Beats per min

Question 58

Define cardiac output

Answer 58

Vol. of blood pumped in a minute

Question 59

Define stroke volume

Answer 59

Vol. of blood in one beat

Question 60

How do you calculate cardiac output

Answer 60

Stroke Volume x Heart Rate