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GCSE AQA Biology > Topic 4- Bioenergetics > Flashcards

Topic 4- Bioenergetics Flashcards

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1
Q

What type of a reaction is photosynthesis?

A

Photosynthesis is endothermic- this means energy is transferred from the environment in the process.

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2
Q

What does photosynthesis use?

A

Photosynthesis uses energy to change carbon dioxide and water into glucose and oxygen.

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3
Q

Where in the plant is energy transferred to for photosynthesis?

A

Energy is transferred to the chloroplasts from the environment by light.

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4
Q

Give the word equation for photosynthesis.

A

Carbon dioxide + water ⟶ glucose + oxygen

⟶ (light)

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5
Q

Give the symbol equation for photosynthesis.

A

6CO₂ + 6H₂O ⟶ C₆H₁₂O₆ + 6O₂

⟶(light)

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6
Q

What are the 5 ways in which plants use glucose?

A
  1. For respiration
  2. Making cellulose
  3. Making amino acids
  4. Stored as oils or fats
  5. Stored as starch
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7
Q

Why is glucose used for respiration in plants?

A

For respiration- This transfers energy from glucose which enables the plants to convert the rest of the glucose into various other useful substances.

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8
Q

Why is glucose used for making cellulose in plants?

A

Making cellulose- Glucose is converted into cellulose for making strong plant cell walls.

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9
Q

Why is glucose used for making amino acids in plants?

A

Making amino acids- Glucose is combined with nitrate ions (absorbed from the soil) to make amino acids, which are then made into protein.

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10
Q

Why is glucose stored as oils or fats in plants?

A

Stored as oils or fats- Glucose is turned into lipids (fats and oils) for storing in seeds.

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11
Q

Why is glucose stored as starch?

A

Stored as starch- Glucose is turned into starch and stored in roots, stems and leaves, ready for use when photosynthesis isn’t happening, like in the winter. Starch is insoluble, which makes it much better for storing than glucose- a cell with lots of glucose in would draw in loads of water and swell up.

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12
Q

Give 3 ways in which the rate of photosynthesis would be affected.

A
  1. Intensity of light
  2. Concentration of CO₂
  3. Temperature
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13
Q

Define the limiting factor.

A

Limiting factor just means that it’s stopping photosynthesis from happening any faster.

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14
Q

How can one of the 3 factors become a limiting factor?

A

One of the 3 factors can become a limiting factor due to environmental conditions.

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15
Q

In which environment does light become the limiting factor?

A

At night the light is the limiting factor.

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16
Q

In which environment does the temperature become the limiting factor?

A

In winter it’s often temperature.

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17
Q

In which environment does CO₂ become the limiting factor?

A

If it’s warm enough and bright enough, the amount of CO₂ is usually limiting.

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18
Q

How can chlorophyll be the limiting factor of photosynthesis?

A
  1. The amount of chlorophyll in a plant can be affected by disease (e.g. infection with the tobacco mosaic virus).
  2. Environmental stress, such as lack of nutrients.

These factors can cause chloroplasts to become damaged or to not make enough chlorophyll. This means the rate of photosynthesis is reduced because they can’t absorb as much light.

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19
Q

What is light used for in photosynthesis?

A

Light provides the energy needed for photosynthesis.

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20
Q

What affect does the increase of light have on the rate of photosynthesis?

A

As the light level is raised, the rate of photosynthesis increases steadily- but only up to a certain point.

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21
Q

Why does the increase of light only have an affect on the rate of photosynthesis up to a certain point?

A

Beyond the point, it won’t make any difference- as light intensity increases, the rate will no longer increase. This is because it’ll be either the temperature or the CO₂ level which is now the limiting factor, not light.

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22
Q

How can you change the light intensity on a plant in a lab?

A

In a lab you can change the light intensity by moving a lamp closer to or further away from your plant.

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23
Q

How do you avoid getting a weird-shaped graph when plotting the rate of photosynthesis against “the distance of lamp from the plant”?

A

You need to either measure the light intensity at the plant using a light meter or you use maths with your results.

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24
Q

What happens to the rate of photosynthesis when CO₂ increases?

A

The amount of CO₂ will only increase the rate of photosynthesis up to a point.

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25
Q

What happens to the graph when CO₂ reaches up to the point?

A

The graph flattens out- as the amount of CO₂ increases the rate no longer increases. This shows that CO₂ is no longer the limiting factor.

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26
Q

What will be the limiting factor if light and CO₂ are in plentiful supply?

A

The factor limiting photosynthesis must be temperature.

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27
Q

What happens if the temperature is the limiting factor for photosynthesis?

A

If the temperature is the limiting factor it’s because it’s too low- the enzymes needed for photosynthesis work more slowly at low temperatures.

28
Q

What happens if the plant gets too hot?

A

If the plant gets too hot, the enzymes it needs for photosynthesis and its other reactions will be damaged.

29
Q

At which temperature does the enzymes get damaged in plants?

A

This happens at about 45°C.

30
Q

Give the inverse square law.

A

Light intensity ∝ 1/ distance (d)²

31
Q

What does the inverse square law mean?

A

The inverse square law means that if you halve the distance, the light intensity will be four times greater and if you third the distance, the light intensity will be nine times greater. Likewise, if you double the distance, the light intensity will be four times smaller and if you treble the distance, the light intensity will be nine times smaller.

32
Q

What is the measure for light intensity?

A

1/d² as a measure for light intensity.

33
Q

What is the measure for light intensity?

A

1/d² as a measure for light intensity.

34
Q

What is the most common way to create the ideal environment for plants?

A

The most common way to artificially create the ideal environment for plants is to grow them in a greenhouse.

35
Q

What do greenhouses help with?

A

Greenhouses help to trap the Sun’s heat, and make sure that the temperature doesn’t become limiting.

36
Q

What do gardeners/ farmers do in winter and summer to keep the temperature at an ideal level?

A

In winter a farmer or gardener might use a heater to keep the temperature at the ideal level. In summer it could get too hot, so they might use shades and ventilation to cool things down.

37
Q

What do commercial farmers do to provide light for their plants?

A

Commercial farmers often supply artificial light after the Sun goes down to give their plants more quality photosynthesis time.

38
Q

How do farmers and gardeners increase the level of CO₂ in the greenhouse?

A

They use a paraffin heater to heat the greenhouse. As the paraffin burns, it makes carbon dioxide as a by-product.

39
Q

Why is it easier to keep plants enclosed in a greenhouse?

A

It is easier to keep the plants free from pests and diseases.

40
Q

What do farmers do to provide minerals to their plants?

A

The farmers can add fertilisers to the soil, to provide all the minerals needed for healthy growth.

41
Q

What is important for the farmers/ gardeners to do when managing greenhouses?

A

It’s important that a farmer supplies just the right amount of heat, light, etc- enough to make the plants grow well, but not more than the plants need, as this would just be wasting money.

42
Q

Why is it important to keep the conditions just right for photosynthesis for plants?

A

It is important because then the plants will grow much faster and a decent crop can be harvested much more often, which can then be sold.

43
Q

a) What is respiration?
b) What type of reaction is respiration?
c) What do all living things do?

A

a) Respiration is the process of transferring energy from the breakdown of glucose (sugar)- and it goes on in every cell in you body continuously.

or

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

b) Respiration is exothermic- it transfers energy to the environment.
c) All living things respire.

44
Q

Give 3 ways in which organisms use the energy transferred by respiration.

A
  1. To build up large molecules from smaller ones (like proteins from amino acids).
  2. In animals it’s used to allow the muscles to contract (so they can move about).
  3. In mammals and birds the energy is used to keep their body temperature steady in colder surroundings. (Unlike other animals, mammals and birds keep their bodies constantly warm.)
45
Q

What are chemical reactions in a cell controlled by?

A

Enzymes

46
Q

Define enzymes.

A

Enzymes are biological catalysts.

47
Q

Give 3 examples in which larger molecules are made from smaller ones.

A
  1. Lots of small glucose molecules are joined together in reactions to form starch (a storage molecule in plant cells), glycogen (a storage molecule in animal cells) and cellulose (a component of plant cell walls).
  2. Lipid molecules are each made from one molecule of glycerol and three fatty acids.
  3. Glucose is combined with nitrate ions to make amino acids, which are then made into proteins.
48
Q

Give 2 examples in which larger molecules are broken down into smaller ones.

A
  1. Glucose is broken down in respiration. Respiration transfers energy to power all the reactions in the body that make molecules.
  2. Excess protein is broken down in a reaction to produce urea. Urea is then excreted in urine.
49
Q

Define metabolism.

A

It is the sum (total) of all the reactions that happen in a cell or the body.

50
Q

Define aerobic respiration.

A

Aerobic respiration is respiration using oxygen. It’s the most efficient way to transfer energy from glucose. Aerobic respiration goes on all the time in plants and animals.

51
Q

Where does most of the reactions in aerobic respiration happen?

A

Most of the reactions in aerobic respiration happen inside mitochondria.

52
Q

Give the word equation for aerobic respiration.

A

glucose + oxygen ⟶ carbon dioxide + water

53
Q

Give the symbol equation for aerobic respiration.

A

C₆H₁₂O₆ + 6O₂ ⟶ 6CO₂ + 6H₂O

54
Q

When does your body start to do anaerobic respiration and aerobic respiration?

A

When you do vigorous exercise and your body can’t supply enough oxygen to your muscles they start doing anaerobic respiration as well as aerobic respiration.

55
Q

Define anaerobic respiration.

A

“Anaerobic” just means “without oxygen”. It’s the incomplete breakdown of glucose, making lactic acid.

56
Q

Give the word equation for anaerobic respiration.

A

glucose ⟶ lactic acid

57
Q

Why does anaerobic respiration not transfer nearly as much energy as aerobic respiration?

A

Glucose isn’t fully oxidised (because anaerobic respiration doesn’t combine with oxygen).

58
Q

Why does anaerobic respiration not transfer nearly as much energy as aerobic respiration?

A

Glucose isn’t fully oxidised (because anaerobic respiration doesn’t combine with oxygen).

59
Q

When is anaerobic respiration useful?

A

Anaerobic respiration is only useful in emergencies, e.g. during exercise when it allows you to keep on using your muscles for a while longer.

60
Q

What are the products of plant and yeast cells when they respire without oxygen?

A

Plants and yeast cells can respire without oxygen too, but they produce ethanol (alcohol) and carbon dioxide instead of lactic acid.

61
Q

Give the word equation for anaerobic respiration in plant and yeast cells.

A

glucose ⟶ ethanol + carbon dioxide

62
Q

What is anaerobic respiration in yeast cells called?

A

Fermentation

63
Q

Why is fermentation by yeast of great value to food and drinks industry?

A

It’s used to make bread and alcoholic drinks, e.g. beer and wine.

64
Q

How does the bread rise in bread-making?

A

In bread-making, it’s the carbon dioxide from fermentation that makes bread rise.

65
Q

How is alcohol produced?

A

In beer and win-making, it’s the fermentation process that produces alchol.

GCSE AQA Biology (7 decks)

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