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gcse science > Science - Biology - Bioenergetics - B4 > Flashcards

Science - Biology - Bioenergetics - B4 Flashcards

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1
Q

what is photosynthesis ?

A

photosynthesis is the process that produces ‘food’ in plants

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2
Q

what is the food produced from photosynthesis that plants need ?

A

glucose - a sugar

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3
Q

what are the reactants in photosynthesis ?

A
  • water
  • carbon dioxide
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4
Q

what are the products of photosynthesis ?

A
  • glucose
  • oxygen
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5
Q

where does photosynthesis take place ?

A

in the chloroplasts in green plant cells

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6
Q

what do the chloroplasts contain ?

A

a pigment called chlorophyll which absorbs light

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7
Q

what type of reaction is photosynthesis ?

A

an endothermic reaction

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8
Q

what is an endothermic reaction ?

A

a reaction where energy is transferred from the environment in the process

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9
Q

how does carbon dioxide leave the leaf cell, and oxygen enter ?

A

diffusion

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10
Q

how does water reach the cell ?

A

through the xylem

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11
Q

what is the word equation for photosynthesis ?

A

carbon dioxide + water - light - glucose + oxygen

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12
Q

what is the symbol equation for photosynthesis ?

A

6CO2 + 6H20 - light - C6H12O6 + 6O2

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13
Q

what are the main things that glucose is used for ?

A
  • respiration
  • making cellulose
  • making amino acids
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14
Q

what is respiration ?

A

a process which occurs in all living organisms, where energy is released from the breakdown of glucose

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15
Q

what is the energy released from glucose, respiration used for ?

A
  • to convert the rest of the glucose into other useful substances
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16
Q

what is cellulose used for ?

A

making strong cell walls to strengthen and support the cells

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17
Q

what are amino acids ?

A

the building blocks which make up proteins

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18
Q

what is combined with glucose to make amino acids ?

A

nitrate ions

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19
Q

how can glucose be stored ?

A

in -
- starch
- lipids

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20
Q

give an example of how glucose is stored in lipids

A

sunflower seeds

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21
Q

why is glucose stored as starch ?

A

so its ready to use when photosynthesis isn’t happening as much, like in the winter

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22
Q

give an example of how glucose is stored in starch

A
  • in roots
  • in stems
  • seeds
  • leaves
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23
Q

why is starch good for storing glucose ?

A

it is insoluble

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24
Q

what does the rate of photosynthesis depend on ?

A
  • intensity of light
  • volume of carbon dioxide
  • temperature
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25
Q

what is a limiting factor ?

A

the factor which is stopping photosynthesis from happening any faster

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26
Q

give an example of when light is a limiting factor for photosynthesis

A
  • at night there’s much less light than there is during the day, so light intensity is usually the limiting factor at night
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27
Q

give an example for when temperature is a limiting factor for photosynthesis

A
  • in winter it is usually cold, so a low temperature is often the limiting factor
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28
Q

give an example of when the volume of carbon dioxide is a limiting factor for photosynthesis

A
  • if it’s warm enough and bright enough, the amount of carbon dioxide is usually limiting
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29
Q

give an example of how chlorophyll is a limiting factor of photosynthesis

A

the amount of chlorophyll in a plant can be affected by disease or environmental stress. These factors cause chloroplasts to become damaged or not to make enough chlorophyll, so photosynthesis is limited as they can’t absorb as much light

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30
Q

describe the graph showing how light intensity affects the rate of photosynthesis

A

the rate increases with light intensity, then the line goes straight

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31
Q

why does the line in the light intensity graph stop increasing ?

A

the rate stops increasing because the temperature or volume of carbon dioxide then becomes the limiting factor, not light

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32
Q

describe the graph showing how carbon dioxide level affects the rate of photosynthesis

A

the rate steadily increases, then stops because the light or temperature becomes the limiting factor

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33
Q

describe the graph showing how temperature affects the rate of photosynthesis

A

it increases, reaches the optimum temperature, then decreases

34
Q

why does the graph showing how temperature affects the rate of photosynthesis decrease after increasing ?

A

if the plant gets too hot, the enzymes it needs for photosynthesis and its other reactions will become damaged

35
Q

what temperature becomes too hot for photosynthesis ?

A

45 degrees and above

36
Q

what are enzymes, and how do they link to photosynthesis ?

A

enzymes are proteins which increase the speed of chemical reactions in living things, so enzymes increase the rate of photosynthesis in plant cells, the speed at which enzymes work is affected by temperature

37
Q

how does having a low temperature, affect a plants ability to photosynthesize ?

A

the enzymes needed for photosynthesis work more slowly at low temperatures

38
Q

what is the control variable ?

A

the thing you keep the same

39
Q

what is the dependent variable ?

A

what you measure

40
Q

what is the independent variable ?

A

what you change

41
Q

give one way/experiment you can do to investigate the rate of photosynthesis

A

by using an aquatic plant, like pondweed and the rate at which the pondweed produces oxygen corresponds to the rate of oxygen production the faster the rate of photosynthesis

42
Q

describe the experiment for investigating the rate of photosynthesis

A
  • a source of white light is placed at a specific distance from the pondweed
  • the pondweed is left for a couple of minutes to adjust to the new light intensity
  • pondweed is left to photosynthesize for a set amount of time
  • as it photosynthesizes the oxygen released will collect in the capillary tube
  • at the end of this experiment the syringe is used to draw the gas bubble in the tube up alongside a ruler and the length of the gas bubble is measured, which is proportional to the volume of oxygen produced
43
Q

what is the dependent variable with the rate of photosynthesis experiment ?

A

the amount of oxygen produced - the size of the oxygen bubble

44
Q

give an example of the control variables in the rate of photosynthesis experiment

A
  • if your plant’s in a flask, keep the flask in a water bath to help keep the temperature constant
45
Q

how do you calculate the rate of photosynthesis in the rate of photosynthesis experiment ?

A

divide the total length of the bubble by the time taken to produce it

46
Q

what is the inverse square law ?

A

the inverse square law means that if you halve the distance, the light intensity will be 4 times greater, and if you third the distance, the light intensity will be 9 times greater, likewise if you double the distance, the light intensity will be 4 times smaller e.t.c

47
Q

how is the inverse square law written out ?

A

light intensity - 1/distance (d2)

48
Q

what are the different ways you can control plant growth ?

A
  • storing them in greenhouses
  • temperature
  • light
  • carbon dioxide concentration
  • general health of plants
49
Q

how can greenhouses maximize plant growth ?

A

greenhouses are made so it has ideal conditions for photosynthesis, which then maximizes the rate of plant growth

50
Q

why do people use greenhouses ?

A

commercial farmers often grow large quantities of plants in commercial greenhouses

51
Q

how is temperature kept in greenhouses?

A

greenhouses help to trap the suns heat, and make sure that the temperature doesn’t become limiting

52
Q

how can temperature be controlled, other than with a greenhouse ?

A
  • in winter, farmers may use a heater in their greenhouse to keep the temperature at an ideal level
  • in summer, greenhouses could get too hot so farmers might use shades and ventilation to cool things down
53
Q

how can greenhouses control the light ?

A

farmers often use artificial light after the sun goes down to give their plants more quality photosynthesis time

54
Q

how can greenhouses control the carbon dioxide concentration ?

A

farmers can increase the carbon dioxide by using a paraffin heater to heat the greenhouse, as the paraffin burns, it makes carbon dioxide as a by product

55
Q

how can greenhouses help keep plants healthy ?

A
  • by keeping plants enclosed in a greenhouse also makes it easier to keep them free from pests and diseases, the farmer can also add fertilizers to the soil as well
56
Q

what is respiration ?

A

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

57
Q

what type of reaction is respiration ?

A

exothermic, it transfers energy to the environment

58
Q

what is an exothermic reaction ?

A

where it transfers energy into the environment

59
Q

what is aerobic respiration ?

A

respiration using oxygen

60
Q

where does aerobic respiration happen in the cell ?

A

mitochondria

61
Q

who does aerobic respiration happen to?

A

plants and animals

62
Q

what is the word equation for aerobic respiration ?

A

glucose + oxygen - carbon dioxide + water

63
Q

what is the symbol equation for aerobic respiration ?

A

C6H12O6 + 6CO2 - 6CO2 + 6H20

64
Q

what do organisms use the energy for respiration for ?

A
  • organisms use energy to build up larger molecules from smaller ones ( proteins from amino acids )
  • animals use energy to allow their muscles to contract - which then allows them to move
  • mammals and birds use energy to keep their body temperature steady
65
Q

what is anaerobic respiration ?

A

respiration that doesn’t require oxygen, it’s the incomplete breakdown of glucose making lactic acid

66
Q

why is anaerobic respiration used ?

A

when you do vigorous exercise and your body can’t supply enough oxygen to your muscles

67
Q

what is the word equation for anaerobic respiration ?

A

glucose - lactic acid

68
Q

why doesn’t anaerobic respiration transfer as much energy as aerobic respiration ?

A

glucose isn’t fully oxidized so anaerobic respiration is only useful in emergencies

69
Q

what is oxygen debt ?

A

the amount of extra oxygen your body needs after exercise, so you have to repay the oxygen you didn’t have to get to your muscles in time because your lungs, heart and blood couldn’t keep up with the demand earlier on

70
Q

what does the oxygen that’s being repaid react with in the muscles to stop the cramps ?

A

lactic acid

71
Q

give another way your body has of coping with the high level of lactic acid

A

the blood that enters your muscles transports the lactic acid to the liver and the lactic acid is converted back to glucose

72
Q

in anaerobic respiration for plants and yeast, what is produced instead of lactic acid ?

A

ethanol and carbon dioxide

73
Q

what is the word equation for anaerobic respiration in plant and yeast cells ?

A

glucose - ethanol + carbon dioxide

74
Q

what is fermentation ?

A

anaerobic respiration in yeast cells

75
Q

why is fermentation by yeast important?

A

it is used to make bread and alcoholic drinks, helps the bread rise, and produces alcohol

76
Q

what does regular physical activity do to your breathing rate and heart rate ?

A
  • increases your breathing rate, and breath volume to meet the demand for extra oxygen
  • increases your heart rate to make your blood flow more quickly, delivering more oxygen and glucose to cells for respiration, and taking more carbon dioxide away
77
Q

what can long periods of exercise cause?

A

muscle fatigue

78
Q

what is the recovery period ?

A

when your breathing rate is higher than usual after anaerobic exercise due to oxygen debt being repaid

78
Q

what is muscle fatigue ?

A

when the muscles get tired and stop contracting efficiently

79
Q

what do enzymes control ?

A

the chemical reactions happening in a cell, many reactions are linked together to form bigger reactions

80
Q

what is metabolism ?

A

all the chemical reactions that happen in a cell or the body

gcse science (27 decks)

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