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Bioenergetics Flashcards

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AP® Biology flashcards Biology 101 flashcards
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 is photosynthesis?

A

An endothermic reaction in which energy is transferred from the environment to the chloroplasts by light.

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4
Q

Where does photosynthesis take place?

A

In chloroplasts in green plant cells (containing green pigments like chlorophyll which absorb light).

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5
Q

What do plants use the glucose produced in photosynthesis for?

A
  • used for respiration
  • converted into insoluble starch for storage
  • used to produce fat or oil for storage
  • used to produce cellulose, which strengthens the cell wall
  • used to produce amino acids for protein synthesis
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6
Q

Why do plants use glucose for respiration?

A

Energy is transferred from glucose which enables the plants to convert the rest of the glucose into various other useful substances.

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7
Q

How do plant use glucose from photosynthesis to make proteins?

A

Glucose is combined with nitrate ions absorbed from the soil to make amino acids, which are then made into proteins.

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8
Q

How do plants convert glucose for storage?

A

-Glucose is converted into lipids (oils and fats) for storing in seeds
-Glucose is converted into insoluble starch and stored in roots, stems, and leaves ready for when photosynthesis isn’t happening, like in the winter

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9
Q

Why is starch better for storing energy than glucose?

A

It is insoluble but glucose isn’t. A cell with lots of glucose in would draw in loads of water via osmosis and swell up.

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10
Q

What are the (limiting) factors that affect the rate of photosynthesis?

A

-Light intensity
-Carbon dioxide concentration
-Temperature
-(Chlorophyll)

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11
Q

How does temperature affect the rate of photosynthesis?

A

-Usually, if the temp is the limiting factor its because it’s too low.
-As temperature increases, the rate of photosynthesis also increases - initially
-After optimum temperature is reached, the rate of photosynthesis decreases

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12
Q

What is a limiting factor?

A

A factor which prevents the rate of photosynthesis increasing any further.

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13
Q

How does Carbon Dioxide concentration affect the rate of photosynthesis?

A

-Increasing the levels of carbon dioxide increases the rate of photosynthesis because it is one of the reactants.
-But only up to a point where the graph will plateau (as CO2 increases, the rate of photosynthesis no longer increases)
-This shows CO2 is no longer the limiting factor

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14
Q

Why might a too low temperature be limiting?

A

The enzymes needed for photosynthesis work more slowly at low temperatures.

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15
Q

Why can’t we measure the rate of growth to measure the rate of photosynthesis?

A

Glucose is used for a variety of things other than growth.

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16
Q

Why might a too high temperature be limiting?

A

The enzymes that catalyse the photosynthesis reaction (and the plant’s other reactions) will denature so will be unable to carry out their function.

This happens at around 45°C and causes the rate of photosynthesis to drop sharply until it stops altogether

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17
Q

How does light intensity affect the rate of photosynthesis?

A

-Light provides the energy needed for photosynthesis
-As light levels increase, so does the rate of photosynthesis, but only up to a point (the graph will plateau)
-Then light is no longer the limiting factor (it will be CO2 conc. or temp.)

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18
Q

How does levels of chlorophyll affect the rate of photosynthesis?

A

-The amount of chlorophyll in a plant can be affected by disease (e.g. TMV) or environmental stress, such as a lack of nutrients.
-These factors can cause chloroplasts to become damaged or to not make enough chlorophyll
-This reduces the rate of photosynthesis because they can’t absorb as much light.

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19
Q

When looking at graphs of photosynthesis rates…

A

-If a line levels of it is no longer the limiting factor
-If there are two lines and one is at a lower temp/conc. then at that line, temp/conc. must be the limiting factor

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20
Q

If factors are high, then…

A

…another factor must be limiting.

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21
Q

How are leaves adapted for photosynthesis?

A

-Wide to increase surface area
-Flat to provide a short diffusion path for Carbon dioxide
-Mesophyll cells have lots of chloroplasts (maximum absorption of light)
-Xylem to transport water (and minerals)
-Phloem to transport glucose produced to rest of plant
-Lower epidermis has spores called stomata (CO2 can diffuse into leaf, O2 can diffuse out).

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22
Q

How can farmers manipulate the rate of photosynthesis?

A

-Artificial lights
-Use heaters
-Increase CO₂ concentration
-Ensure plants have enough minerals and nitrates
-Greenhouses

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23
Q

How do greenhouses increase the rate of photosynthesis?

A

Trap the sun’s heat to make sure temperature doesn’t become limiting.

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24
Q

How do heaters/ventilation increase the rate of photosynthesis?

A

In winter a farmer might use a heater to keep temp. at the right level
In summer, they might use shades/ventilation to cool things down when they get too hot

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25
Q

How does using artificial lights increase the rate of photosynthesis?

A

Gives plants more quality photosynthesis time.

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26
Q

How do farmers increase the rate of photosynthesis by manipulating levels of carbon dioxide?

A

By using a paraffin heater to heat the greenhouse. As the paraffin burns, it makes CO2 as a by-product.

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27
Q

Pros of farmers using light and heaters to increase the rate of photosynthesis in crop farming.

A

Gas heaters will warm up the greenhouse and give off carbon dioxide, increasing the rate of photosynthesis.
Artificial lights means plants can be lit during the night, increasing the rate of photosynthesis particularly within the winter months.

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28
Q

Cons of farmers using light and heaters to increase the rate of photosynthesis in crop farming.

A

Gas used in gas heaters is a fossil fuel, adding additional CO2 to the atmosphere, contributing to the enhanced greenhouse effect.
Artificial lights run on mains electricity which can be expensive.

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29
Q

Limiting factors are important in the economics of …

A

… enhancing the conditions in greenhouses to gain the maximum rate of photosynthesis while still maintaining profit.

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30
Q

What does the inverse square law state?

A

Light intensity decreases in proportion to the square of the distance.

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31
Q

Inverse square law formula:

A

light intensity ∝ 1/d²

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32
Q

The inverse square law means that if you halve the distance, the light intensity will be…

A

four times greater

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33
Q

The inverse square law means that if you double the distance, the light intensity will be…

A

four times smaller

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34
Q

What is a measure of light intensity?

A

1/d²

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35
Q

What is cellular respiration?

A

An exothermic reaction that transfers energy from the breakdown of glucose. It is continuously occurring in all living cells.

36
Q

What does the energy transferred in respiration do?

A

Supplies the energy needed for all living processes.(for cells)

37
Q

In what way can respiration take place in cells?

A

Aerobically or Anaerobically.

38
Q

What is aerobic respiration?

A

Respiration with oxygen

39
Q

What is anaerobic respiration?

A

Respiration without oxygen.

40
Q

Is more energy transferred in aerobic or anaerobic respiration?

A

Aerobic

41
Q

Why is less energy transferred in anaeorobic respiration?

A

The oxidation of glucose is incomplete (it doesn’t combine with oxygen).

42
Q

What do organisms need energy for?

A
  • chemical reactions to build larger molecules (like proteins from amino acids)
    *movement (muscle contractions in animals)
  • keeping warm (mammals and birds - to keep body temp steady in colder surroundings).
43
Q

What is the equation for aerobic respiration?

A

glucose + oxygen carbon dioxide + water

44
Q

What is the symbol equation for aerobic respiration?

A

C6H12O6 + 6O2 → 6CO2 + 6H2O

45
Q

What is the word equation for anaerobic respiration?

A

glucose → lactic acid

46
Q

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

A

glucose → ethanol + carbon dioxide

47
Q

What is anaerobic respiration in yeast cells called?

A

Fermentation

48
Q

Why is fermentation of economic importance in the manufacture of bread and alcoholic drinks?

A

-In bread-making, the CO2 makes the bread rise.
-In beer and wine making, it’s the fermentation process that produces alcohol.

49
Q

aerobic respiration

A

-Respiration using oxygen
-The most efficient way to transfer energy from glucose
-Most of the reactions in aerobic respiration happen inside mitochondria
-Transfers energy from glucose

50
Q

anaerobic respiration.

A

-Used when your body can’t supply enough oxygen to your muscle cells for aerobic respiration
-it is the incomplete breakdown of glucose, making lactic acid as a waste product
-Doesn’t transfer as much energy as aerobic respiration as oxidation of glucose is incomplete
-So, only useful in emergencies e.g. during exercise when it allows you to use your muscles for longer.

51
Q

Where does energy come from in humans and how is it transferred?

A

Food and by respiration

52
Q

Why is respiration an exothermic reaction?

A

It transfers energy to the environment.

53
Q

During exercise the human body…

A

… reacts to the increased demand for
energy

54
Q

Explain what happens to the human body when exercising.

A

-Muscles contract when a person is exercising which requires energy from aerobic respiration

-The heart rate increases to increase the blood flowing to muscles, providing them with more oxygen and glucose for increased aerobic respiration

-The breathing rate and breathing volume increase to supply the lungs with more air, so more oxygen enters the bloodstream

-This removes CO₂ more quickly at the same time.

-Anaerobic respiration occurs due to a lack of oxygen which leads to an oxygen debt

-Muscles become fatigued

-Anaerobic respiration can also cause a build-up of lactic acid, causing muscular pain

55
Q

How does the body react to supply muscles with more oxygenated blood during exercise?

A

The heart rate, breathing rate and breath volume increase.

56
Q

What happens if insufficient oxygen is supplied to muscles?

A

Anaerobic respiration takes place in
muscles.

57
Q

What is the problem with anaerobic respiration?

A

The incomplete oxidation of glucose causes a build up of lactic acid and creates an oxygen debt. The build up of lactic acid in the muscles causes painful muscle cramps. During long periods of vigorous activity muscles become fatigued and stop contracting efficiently.

58
Q

What happens to the lactic acid produced?

A

Blood flowing through the muscles transports the lactic acid to the liver where it is converted back into glucose.

59
Q

What is the oxygen debt?

A

The amount of extra oxygen the body needs after exercise to react with the accumulated lactic acid and remove it from the cells.

60
Q

How is the oxygen debt repaid?

A

-Breathing volume stays high after you stop exercising to get more oxygen into your blood, which is transported to the muscle cells.
-Pulse and breathing rate stay high whilst there are high levels of lactic acid and CO2
-Lactic acid is transported to the liver by blood that enters your muscles where it is either oxidised to carbon dioxide and water, or converted to glucose, then glycogen for storage.

61
Q

How can we measure breathing rate?

A

Counting breaths.

62
Q

How can we measure heart rate?

A

Taking the pulse.

63
Q

How can we reduce the effect of random errors on experimental results? (effects of exercise on the body)

A

Do it as a group and plot the average pulse rate for each exercise.

64
Q

What is metabolism?

A

The sum of all the chemical reactions in a cell or body.

65
Q

How do respiration and metabolism relate?

A

The energy transferred by respiration in cells is used by the organism for the continual enzyme controlled processes of metabolism , (the reactions that) synthesise new molecules.

66
Q

What does metabolism include?

A
  • conversion of glucose to starch, glycogen and cellulose
  • the formation of lipid molecules from a molecule of glycerol and three fatty acid molecules
  • the use of glucose and nitrate ions to form amino acids which in turn are used to synthesise proteins
  • glucose broken down in respiration
  • breakdown of excess proteins to form urea for excretion.
67
Q

Describe two differences between aerobic and anaerobic respiration in humans.

A

Anaerobic respiration produces lactic acid and aerobic doesn’t.

Anaerobic releases less energy than aerobic.

Aerobic produces carbon dioxide/water and anaerobic does not.

Aerobic occurs mainly in the mitochondria and anaerobic does not.

68
Q

Describe how energy for the photosynthesis reaction is gained by plants.

A

Light is absorbed by chlorophyll.

69
Q

Why might a result be anomalous?

A

Scale misread
Different masses
Temp change

70
Q

Why is measuring the number of gas bubbles produced per unit time not a completely valid experimental method for measuring the rate of photosynthesis?

A

We make the assumption that all the gas in the bubbles is oxygen, even though we know it’s not.

As plants are continually respiring, some of the gas in the bubbles will be carbon dioxide.

71
Q

Validity

A

How appropriate an experimental method is at achieving the aim of an experiment.

72
Q

Reliability

A

The ability of an experiment to produce consistent results.

73
Q

Accuracy

A

How close a measured value is to its true value.

74
Q

How can you improve the accuracy of your measurements in the photosynthesis experiment?

(counting bubbles can be tricky and imprecise).

A

The measurements can be improved by using a gas syringe or upturned measuring cylinder filled with water.

75
Q

Light intensity, temperature or amount of chlorophyll limit the rate of photosynthesis because…

A

…they either reduce reactants for the reaction to take place, reduce the energy which aids the chemical reaction, or reduce the pigment which absorbs light.

76
Q

How can we control limiting factors which affect the rate of photosynthesis?

A

By growing plants in a greenhouse.

77
Q

Negative of using greenhouses to increase the rate of photosynthesis.

A

Cost.

If lighting and heating are very expensive, it may not be economical.

78
Q

Farmers must evaluate the trade-off between what?

A

The costs of lighting and heating, and the rate of photosynthesis that is possible

79
Q

Why is mineral deficient soil a problem?

A

If plants are grown in mineral-deficient soil, they may not absorb enough minerals to produce lots of chlorophyll.

In this case, chlorophyll concentration can be the limiting factor.

80
Q

Why is nitrogen from the soil important to plants?

A

Nitrate ions are important components of amino acids.

Nitrogen therefore plays a substantial role in the growth of plant cells and tissues.

81
Q

What type of reaction is photosynthesis and why?

A

Endothermic because it requires energy.

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

82
Q

Where does the photosynthesis reaction take place?

A

Photosynthesis takes place mainly in the leaves of a plant, specifically in the chloroplasts which contain the green pigment chlorophyll.

It also takes place inside chloroplasts in algae.

83
Q

Define photosynthesis

A

Photosynthesis is an endothermic reaction in which energy transferred by light is converted to a chemical stored in glucose.

84
Q

What can a plant do if it wanted to use the energy generated by photosynthesis again in the future?

A

It can release the energy through respiration in the mitochondria.

85
Q

Why does increasing the temperature increase the rate of photosynthesis?

A

More energy is provided.

Biology (18 decks)

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