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ZZ Biology P1 > bioenergetics > Flashcards

bioenergetics Flashcards

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1
Q

What is the equation for photosynthesis?

A
  • carbon dioxide + water -> 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

Define 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 the leaves which contain palisade cells that contain the chemical chlorophyll
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5
Q

What is the function of chlorophyll and where is it found?

A
  • found in chloroplasts
  • absorbs the light energy needed for photosynthesis
  • energy is transferred from the environment to the chloroplasts via light
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6
Q

What are the factors that effect the rate of photosynthesis?

A
  • temperature
  • light intensity
  • carbon dioxide concentration
  • amount of chlorophyll
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7
Q

What is the effect of light intensity on the rate of photosynthesis?

A
  • initially, as light intensity increases, the rate of photosynthesis increases - at this point, light intensity is the limiting factor (light intensity is what is stopping the rate from increasing)
  • at one point, the graph flattens out and, as we increase the light intensity, the rate of photosynthesis does not change – light is no longer the limiting factor: temperature or CO₂ is
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8
Q

What is the effect of carbon dioxide on the rate of photosynthesis?

A
  • initially, as CO₂ concentration increases, the rate of photosynthesis increases - at this point, the CO₂ is the limiting factor
  • at one point, the graph flattens out, - CO₂ concentration is no longer the limiting factor (light or temperature is)
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9
Q

What is the effect of temperature on the rate of photosynthesis?

A
  • initially, as temperature increases, the rate of photosynthesis increases - particles have more kinetic energy so react faster
  • at a certain point, it reaches a maximum then rapidly decreases; this is because photosynthesis is an enzyme-controlled reaction
  • once it reaches past the optimum temperature, enzymes denature and the rate of reaction rapidly decreases
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10
Q

What is the effect of the amount of chlorophyll on the rate of photosynthesis?

A
  • chlorophyll is a chemical needed for photosynthesis - it is how energy is absorbed by light
  • a lack of chlorophyll will reduce the rate of photosynthesis (magnesium deficiency)
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11
Q

How do we measure the rate of photosynthesis?

A
  • light intensity is inversely proportional to distance squared
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12
Q

Define limiting factor

A
  • An environmental condition which, in low levels, restricts any increase in the rate of photosynthesis
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13
Q

Why are limiting factors important?

A
  • they’re important in the economics of enhancing the conditions in greenhouses to gain the maximum rate of photosynthesis while still maintaining profit
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14
Q

Why is it important that farmers and gardeners know the ideal conditions for photosynthesis?

A
  • they can create an environment that maximises the rate of photosynthesis
  • this maximises the rate of plant growth, thus crop yield and thus profit
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15
Q

Why should a greenhouse be used to maximise the rate of photosynthesis?

A
  • conditions can be easily controlled
  • easier to keep plants free from pests and diseases
  • farmers can add fertilisers to the soil
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16
Q

How do greenhouses work to maximise the rate of photosynthesis for temperature?

A
  • greenhouses trap heat in from the Sun and ensure temperature isn’t a limiting factor
  • if temp is too hot, shades and ventilation by opening windows can cool it down
  • electric heaters can be used to keep temp at optimal levels for photosynthesis
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17
Q

How do greenhouses work to maximise the rate of photosynthesis for light intensity

A
  • artificial light after the Sun goes down to give plants more time for photosynthesis, so rate of growth increases
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18
Q

How do greenhouses work to maximise the rate of photosynthesis for CO2 concentrations?

A
  • using paraffin heaters
  • releases heat and carbon dioxide as a by-product – ensuring CO2 is not limiting
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19
Q

How can farmers ensure crop yields are maximised?

A
  • farmers can spend more money in creating ideal conditions for photosynthesis
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20
Q

What do farmers need to ensure when maximising crop yields?

A
  • the increased cost of conditions must be justified by the increase in crop-yield to ensure that the conditions created are cost-effective and help increase profit
21
Q

Why must limiting factors be taken into account?

A
  • so that plants are only supplied with what they need - there is no money being wasted.
    e.g. if they spend lots of money to pump in loads of CO₂ but it isn’t limiting, money is being wasted
22
Q

What are the uses of glucose?

A
  • Fats
  • Oils
  • Respiration
  • Starch
  • Amino acids
  • Cellulose
23
Q

How is glucose used in relation to fat and oil?

A
  • fats and oils are ways of storing the energy
  • glucose is turned into lipids and used to store energy in seeds and tubers
24
Q

How is glucose used in relation to respiration?

A
  • respiration needs glucose in order to release energy needed for metabolic reactions
25
Q

How is glucose used in relation to starch?

A
  • glucose is turned into starch and stored in roots, stems, and leaves - ready to use when photosynthesis isn’t happening, can still release energy by respiration (e.g. in the winter)
  • starch is insoluble, makes it better for storing than glucose - a cell with lots of glucose would draw in water and swell up
26
Q

How is glucose used in relation to cellulose?

A
  • cellulose is a complex carbohydrate used to strengthen cell walls
27
Q

How is glucose used in relation to amino acids?

A
  • glucose and nitrate ions (absorbed from the soil) are combined to make amino acids
  • these are needed for protein synthesis to allow growth
28
Q

Define cellular respiration

A
  • process of transferring energy from the breakdown of glucose
  • it is continuously occurring in all living cells
  • an exothermic reaction (it releases energy to the surroundings)
  • the energy transferred supplies all the energy needed for living processes
29
Q

Name the two types of respiration

A
  • aerobic respiration (using oxygen) - takes place in the mitochondria
  • anaerobic respiration (without oxygen) - takes place in the cytoplasm
30
Q

What is the equation for aerobic respiration?

A
  • glucose + oxygen -> carbon dioxide + water
31
Q

What is the equation for anaerobic respiration in muscles?

A
  • glucose -> lactic acid
32
Q

Compare the relative amount of energy transferred in aerobic and anaerobic respiration

A
  • aerobic releases a very large amount of energy because the glucose molecule is fully oxidised
  • anaerobic also releases energy, but much less than aerobic respiration - glucose undergoes incomplete oxidation (rather than being fully oxidised like in aerobic)
33
Q

Compare aerobic and anaerobic respiration in relation to oxygen

A
  • aerobic takes place in the presence of oxygen
  • anaerobic only takes place when there is insufficient oxygen
34
Q

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

A
  • glucose -> ethanol + carbon dioxide
35
Q

What is the significance of anaerobic respiration in plant and yeast cells?

A
  • in yeast cells it is called fermentation
  • has economic importance in the manufacture of bread (the carbon dioxide produced allows bread to rise) and the manufacture of alcoholic drinks (ethanol produced can be used in them)
36
Q

What do organisms need energy for?

A
  • to build up larger molecules from smaller ones
  • movement - allows the muscles to contract
  • keeping warm - keep body temp steady
37
Q

What happens during exercise?

A
  • the body needs to react to the increased demand for energy
38
Q

During exercise, what supplies the muscles with more oxygenated blood?

A
  • heart rate
  • breathing rate
  • breath volume
39
Q

Why does heart rate increase during exercise?

A
  • to get the oxygenated blood around the body faster - to muscles so they respire quickly
  • also removes CO₂ more quickly
40
Q

Why does breathing rate increase during exercise?

A
  • get more oxygen into the blood
41
Q

Why does breathing volume increase during exercise?

A
  • get more oxygen in the blood
42
Q

What happens if insufficient oxygen is supplied during exercise?

A
  • anaerobic respiration takes place in the muscles
  • the body is unable to supply the cells with sufficient oxygen
  • incomplete oxidation of glucose causes a build up of lactic acid, creating an oxygen debt
  • during long periods of vigorous activity, muscles become fatigued and stop contracting efficiently
  • pulse and breathing rate remain high whilst there are high levels of lactic acid and CO₂
43
Q

What is 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
44
Q

What happens after intense exercise?

A
  • blood flowing through the muscles transports the lactic acid (produced from anaerobic respiration) to the liver
    *it is converted back into glucose
45
Q

Why is lactic acid bad?

A
  • it causes fatigue - muscles become tired and do not contract properly
46
Q

How can you investigate the effect of exercise on the body?

A
  • measure breathing rate by counting breathes, and heart rate by taking the pulse
  • measure pulse after sitting down, walking, jogging, and running
  • plot results in a bar chart - pulse will increase the more intense the exercise
  • reduce random error by plotting average pulse rate
47
Q

Define metabolism

A
  • the sum of all the (chemical) reactions in a cell or the body
48
Q

How are new molecules synthesised?

A
  • the energy transferred by respiration in cells is used by the organism for the continual enzyme controlled processes of metabolism that synthesise new molecules
49
Q

What does metabolism include?

A
  • converting glucose into cellulose in plants
  • converting glucose into starch in plants
  • converting glucose into glycogen in animals
  • forming lipid molecules from a molecule of glycerol and three molecules of fatty acids
  • the use of glucose and nitrate ions to form amino acids which in turn are used to synthesise proteins
    respiration
  • the breakdown of excess proteins to form urea for excretion

ZZ Biology P1 (4 decks)

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