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GCSE AQA Combined Science Biology 9-1 > Topic 4 - Bioenergetics > Flashcards

Topic 4 - Bioenergetics Flashcards

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1
Q

Where does photosynthesis take place?

A

It takes place inside chloroplasts found in plants and algae.

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2
Q

Is photosynthesis endothermic or exothermic?

A

Photosynthesis is endothermic meaning it requires energy.

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3
Q

What does photosynthesis convert carbon dioxide and water into?

A

It converts them into oxygen and glucose.

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4
Q

What is the word equation for photosynthesis?

A

carbon dioxide + water –> oxygen + glucose

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5
Q

What is the energy source for photosynthesis and where is it?

A

The source of energy is sunlight, which is trapped by a chemical called chlorophyll inside chloroplasts in plant cells.

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6
Q

What is the symbol equation for photosynthesis?

A

6CO2 + 6H20 –> C6H12O6 + 6O2

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7
Q

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

A

Chlorophyll concentration, carbon dioxide concentration, temperature and light intensity.

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8
Q

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

A

High chlorophyll concentration gives a high rate of photosynthesis.

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9
Q

How does carbon dioxide concentration affect the rate of photosynthesis?

A

Increasing the carbon dioxide concentration increases the rate of photosynthesis. However, above a certain threshold, further increases in the carbon dioxide concentration do not increase the rate of photosynthesis because another factor (like light intensity) is limiting the rate of reaction.

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10
Q

How does temperature affect the rate of photosynthesis?

A

Increasing the temperature increases the rate of photosynthesis because more energy is provided. However, if the temperature is increased to above about 45°C, the enzymes that catalyse the reaction begin to denature. This causes the rate of the reaction to drop sharply until it stops altogether.

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11
Q

How does light intensity affect the rate of photosynthesis?

A

Increasing light intensity increases the rate of photosynthesis because more energy is provided. However, if the light intensity is increased above a certain threshold, the rate of photosynthesis will not increase because another factor (like temperature) is limiting the rate of reaction.

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12
Q

What is a limiting factor?

A

A limiting factor restricts the rate of reaction.

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13
Q

What is the limiting factor for photosynthesis at night?

A

At night, light intensity is the limiting factor.

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14
Q

What is the limiting factor for photosynthesis at winter?

A

In winter, the temperature is the limiting factor.

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15
Q

What is the limiting factors for photosynthesis in warm and bright conditions?

A

In warm and bright conditions, carbon dioxide concentration is usually the limiting factor.

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16
Q

What is the limiting factors for photosynthesis in mineral-deficient soil?

A

If plants are grown in mineral-deficient soil, they may not absorbs enough minerals to produce lots of chlorophyll. In this case, chlorophyll concentration can be the limiting factor.

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17
Q

How does lighting and heating affect rate of photosynthesis and yield?

A

Lighting and heating increase the rate of photosynthesis that is possible. A high rate of photosynthesis means that crops grow faster and the total yield is bigger.

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18
Q

What happens if the farmers costs are high?

A

If lighting and heating are very expensive, it may not be possible to spend money on increasing the light intensity and temperature of a greenhouse. Farmers must evaluate the trade-off (balance) between the costs of lighting and heating, and the rate of photosynthesis that is possible.

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19
Q

What are the can glucose be converted into?

A

Cellulose, fats and oils, starch and protein.

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20
Q

Why is cellulose a good use of glucose?

A

Cellulose is used to strengthen cell walls. It is particularly important for fast-growing plants.

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21
Q

Why are fats and oils a good use of glucose?

A

They are stored in structures such as seeds.

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22
Q

Why is starch a good use of glucose?

A

Starch is insoluble (cannot be dissolved) and is stored in stems, leaves or roots.

23
Q

Why are proteins a good use of glucose?

A

Proteins are needed for cell growth and repair. A source of nitrogen is also needed for glucose to be converted into proteins. Plants get this nitrogen by absorbing nitrate ions from soil.

24
Q

What is glucose produced by photosynthesis mainly used by?

A

Plants in respiration.

25
Q

How can you test the rate of photosynthesis?

A

Using an aquatic (lives in water) plant like pondweed. To do this, change the distance between the lamp and the pondweed and count the number of bubbles produced.. In this experiment, light intensity is the independent variable and the number of bubbles is the dependent variable.

26
Q

What does the rate that pond weed produces bubbles indicate?

A

It indicates the rate of photosynthesis. The bubbles released are oxygen, a waste product of photosynthesis.

27
Q

What is the inverse square law?

A

Light intensity = 1 / distance^2

28
Q

Why do organisms need energy?

A

Contraction - to contract the muscles of animals, allowing them to move.
Construction - to make larger molecules from smaller molecules.
Homeostasis - to keep the body temperature of warm-blooded animals relatively constant.

29
Q

What is respiration?

A

Respiration is an exothermic reaction (releases energy) that supplies all the energy needed by living organisms. This reaction happens continuously in all living cells.

30
Q

What is aerobic respiration?

A

Aerobic means with oxygen. Glucose reacts with oxygen in the mitochondria of cells to give carbon dioxide, water and energy.

31
Q

What is the word equation for aerobic respiration?

A

Glucose + oxygen –> carbon dioxide + water (+energy)

32
Q

What is the symbol equation for aerobic respiration?

A

C6H12O6 + 6O2 –> 6CO2 + 6H20 (+energy)

33
Q

How does anaerobic respiration work in plants?

A

Anaerobic means without oxygen. In plants and yeast cells, glucose is converted into ethanol and carbon dioxide. In yeast cells, this is called fermentation. This is an important step in the manufacture of both bread and alcohol.

34
Q

What is the word equation for anaerobic respiration in plants?

A

Glucose –> ethanol + carbon dioxide

35
Q

How does anaerobic respiration work in animals?

A

Glucose is not broken down completely, making it a less efficient way of transferring energy than aerobic respiration. In animals, glucose is converted to lactic acid.

36
Q

What is the word equation for anaerobic respiration in animals?

A

Glucose –> lactic acid

37
Q

When does anaerobic respiration happen?

A

When insufficient oxygen reaches the muscles during periods of intense activity.

38
Q

What is metabolism?

A

Metabolism is the combination of all the chemical processes that happen in an organism. Many of these create new molecules with the help of enzymes.

39
Q

What are examples of metabolic reactions?

A

Converting glucose, making lipids, breaking down excess proteins and making amino acids.

40
Q

How does the metabolic reaction of converting glucose work?

A

Converting glucose into starch (plants), glycogen (animals) and cellulose (plants).

41
Q

How does the metabolic reaction of making lipids work?

A

Combining glycerol and fatty acid chains to make lipid molecules.

42
Q

How does the metabolic reaction of breaking down excess proteins work?

A

Breaking down excess proteins to form urea, which is excreted (got rid of) in urine.

43
Q

How does the metabolic reaction of making amino acids work?

A

Combining glucose and nitrate ions to make amino acids. Amino acids can then be combined to make proteins.

44
Q

Why do we need to increase the rate of respiration when exercising?

A

Exercise increases the body’s energy demands. The rate of respiration must increase in order to meet these new demands.

45
Q

What are the main responses to increase the rate of respiration?

A

Increase in breath volume, blood vessels dilate, increased heart rate and increase in breathing rate.

46
Q

Why do we need an increase in breath volume to increase the rate of respiration?

A

Increase in breath volume also increases the rate of gas exchange.

47
Q

Why do blood vessels dilate to increase rate of respiration?

A

Blood vessels dilate (open wider) to ensure more blood reaches the muscles.

48
Q

Why does our heart rate increase to increase the rate of respiration?

A

Increase in heart rate delivers more blood (containing glucose and oxygen) to the muscles.

49
Q

Why does our breathing rate increase to increase the rate of respiration?

A

An increase in breathing rate increases gas exchange in the lungs, with more oxygens taken in and more carbon dioxide released.

50
Q

What happens when muscles are not supplied with enough oxygen during intense exercise?

A

Muscle cells may start to respire anaerobically, this can lead to oxygen debt.

51
Q

What is lactic acid?

A

Lactic acid is a by-product of anaerobic respiration. Lactic acid is toxic and can build up in muscles, leading to muscular pain and fatigue. Lactic acid also stops muscles contracting efficiently.

52
Q

What is oxygen debt?

A

Oxygen debt refers to the extra oxygen required after exercise to oxidise (combine with oxygen) lactic acid and remove it from cells.

53
Q

How do you repay oxygen debt?

A

Blood transports the lactic acid to the liver, where it reacts with oxygen to produce carbon dioxide and water. Heavy breathing after exercise helps to repay the oxygen debt by taking more oxygen into the lungs.

GCSE AQA Combined Science Biology 9-1 (7 decks)

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