Bioenergetics Flashcards

Paper 1 - B4

1
Q

What is the word equation for photosynthesis?

A

carbon dioxide + water –light–> glucose + oxygen

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2
Q

What is the symbol equation for photosynthesis?

A

6CO2 + 6H2O –> C6H12O6 + 6O2

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3
Q

What type of reaction is photosynthesis and why?

A

Endothermic because energy is transferred from the environment to the chloroplasts by light

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4
Q

State the four factors that affect the rate of photosynthesis

A

Temperature, light intensity, carbon dioxide concentration and amount of chlorophyll

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5
Q

Why does a change in temperature affect the rate of photosynthesis?

A

Because photosynthesis involves enzymes which work better at higher temperatures but denature at extremes of temperature

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6
Q

Why would the line on a graph of rate of photosynthesis against light intensity level off?

A

Because at high light intensities, something else is limiting the rate, such as carbon dioxide concentration

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7
Q

How could we use the inverse square law to work out the light intensity in the pondweed investigation?

A

Calculate 1/distance^2 so when the distance doubles, the light intensity is divided by 4.

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8
Q

Why do plant growers need to consider limiting factors when deciding how much to spend on enhancing conditions in a greenhouse?

A

Increasing a limiting factor (e.g. light intensity) can increase the rate of photosynthesis, but only up to a point. Increasing it further wouldn’t make a difference and can also be expensive.

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9
Q

What are the ways in which the plants use the glucose produced in photosynthesis?

A

Respiration; converted to starch; fats and oils; cellulose to strengthen cell wall; amino acids for protein synthesis

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10
Q

Why is glucose converted to starch for storage by plants and not just left as glucose?

A

Starch is insoluble. This means it will not move out of the cell and will not affect osmosis

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11
Q

Plants can convert glucose from photosynthesis into amino acids for protein synthesis. What ions are added from the soil to do this?

A

Nitrate ions

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12
Q

What type of reaction is cellular respiration and why?

A

Exothermic because energy is released

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13
Q

What is the purpose of respiration?

A

To transfer energy for living processes

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14
Q

Which type of respiration requires oxygen?

A

Aerobic respiration

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15
Q

Which type of respiration does not require oxygen?

A

Anaerobic respiration

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16
Q

Which type of respiration releases less energy per molecule of glucose?

A

Anaerobic respiration

17
Q

What is produced in anaerobic respiration but not in aerobic respiration?

A

Lactic acid

18
Q

Give 3 reasons why energy from respiration is needed in the body

A

For chemical reactions to build larger molecules; for movement; for keeping warm

19
Q

Write the word equation for aerobic respiration

A

glucose + oxygen –> carbon dioxide + water

20
Q

What is the symbol equation for respiration?

A

C6H12O6 + 6O2 –> 6CO2 + 6H2O

21
Q

Write the word equation for anaerobic respiration in muscles

A

glucose –> lactic acid

22
Q

Write the word equation for anaerobic respiration in plant and yeast cells

A

glucose –> ethanol + carbon dioxide

23
Q

Why is less energy transferred in anaerobic respiration than in aerobic respiration

A

Oxidation (breakdown) of glucose is incomplete, so not all the energy is released

24
Q

What is the name of anaerobic respiration in yeast cells?

A

Fermentation

25
Why is fermentation useful?
Produces ethanol for alcoholic drinks and carbon dioxide to make bread rise
26
State 3 things that increase in the body during exercise
Heart rate, breathing rate and breath volume
27
Why does heart rate increase during exercise?
To supply the muscles with more oxygenated blood for respiration
28
Why might a person doing exercise experience muscle pain and fatigue?
There is insufficient oxygen for aerobic respiration, so they do anaerobic respiration too. This causes lactic acid to build up in the muscles.
29
What is meant by the 'oxygen debt' during exercise?
The amount of extra oxygen the body needs after exercise to react with lactic acid and remove it from the cells.
30
What happens to the lactic acid after exercise and in which organ?
Converted back into glucose in the liver
31
What is metabolism?
The sum of all the reactions in a cell or body
32
What are some examples of metabolism in humans?
Conversion of glucose to starch, glycogen & cellulose; formation of lipids from glycerol & 3 fatty acids; use of glucose & nitrate ions to form amino acids for protein synthesis; respiration; breakdown of excess proteins to form urea for excretion.