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GCSE Biology > Topic 4: Bioenergetics > Flashcards

Topic 4: Bioenergetics Flashcards

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1
Q

where does photosynthesis take place?

A

in the chloroplasts in green plant cells- they contain pigments like chlorophyll that absorb light

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2
Q

what does endothermic mean?

A

that energy in transferred from the environment

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3
Q

what is the equation for photosynthesis?

A

carbon dioxide + water –> glucose + oxygen

6CO2 + 6H2O –> C6H12O6 + 6O2

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4
Q

what do plants use glucose for?

A

1) for respiration: this transfers energy from glucose which enables the plant to make other useful substances
2) Making cellulose: glucose is converted into cellulose to make a strong cell wall
3) Making amino acids: glucose combines with nitrate ions from the soil which combine to make amino acids which are then turned into proteins
4) stored as oils or fats: glucose is turned into lipids for storing seeds
5) stored as starch: Glucose is turned into starch and stored in roots, stems and leaves which makes it better than storing glucose as glucose causes the leaf to draw in water and swell up

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5
Q

what is photosynthesis effected by?

A

1) intensity of light
2) concentration of CO2
3) tempature
4) lack of or damaged chlorophyll

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6
Q

what are limiting factors of photosynthesis?

A
  • at night light is a limiting factor
  • in winter its temperature
  • if warm and bright then CO2
  • from disease, environmental stress (eg lack of nutrients) chlorophyll can get damaged or not make enough chlorophyll
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7
Q

what provides the energy needed for photosynthesis?

A

light

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8
Q

what happens if you increase the amount of light the plant gets?

A

the rate of photosynthesis will increase to a point then it will stay the same as temperature or CO2 will be the limiting factor. a graph would look like this:
__________________________________-
/
/ rate of
/ photosynthesis
/
/
/
light intensity

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9
Q

what happens if you increase the amount of CO2 a plants gets?

A

the rate of photosynthesis will increase to a point then it will stay the same as temperature or light will be the limiting factor. a graph would look like this:
__________________________________-
/
/ rate of photosynthesis
/
/
/
/
% level of CO2

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10
Q

why is temperature a limiting factor?

A

because at low temperatures the enzymes work slowly

but at too high temperatures the enzymes get damaged this is normally at 45 degrees Celsius

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11
Q

what happens if you increase the temperature of a plant?

A

photosynthesis levels will increase to a point and then decrease until 45 degrees (when no photosynthesis happens)

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12
Q

what could a graph of rate of photosynthesis show?

A

it can show more that one factor being explored at once for example level of CO2 and light intensity on the same graph

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13
Q

REQUIRED PRACTICAL: how can Canadian pond weed be used to show rate of photosynthesis?

A

1) a source of whit light is placed at a specific distance from the pond weed
2) The pond-weed is left to photosynthesise for a set amount of time. as it photosynthesises the oxygen released will collect in the capillary tube
3) at the end of the 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. this is proportional to the O2 produced
4) any variables that could effect the experiment should be controlled eg temperature and time
5) the experiment is repeated twice with the light source at the same distance and the mean volume of O2 is calculated
6) the whole experiment is repeated at different distances from the light source

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14
Q

what is the formula that links light intensity and distance?

A

light intensity is directly proportional to 1/distance squared
1/d2

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15
Q

use the inverse square law to calculate the light intensity when the lamp is 10cm from the pond-weed?

A

1/d2
d=10
10 squared = 100
1/100= 0.01 a.u

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16
Q

what is the best way to artificially get a good environment for plants?

A

greenhouse

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17
Q

how do greenhouses work?

A

they trap the suns heat

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18
Q

how could farmers make sure CO2 is not a limiting factor for photosynthesis?

A

they could put a paraffin heater in the greenhouse which produces CO2 as a by product

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19
Q

why would farmers want their plants to photosynthesise?

A

it would make them grow faster

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20
Q

what is respiration?

A

the process of transferring energy from the breakdown of sugar and goes on in every cell constantly

21
Q

what does exothermic mean?

A

energy is transferred to the enviroment

22
Q

how do organisms use the energy transferred from respiration?

A

1) to build up larger molecules from smaller ones
2) allows muscles to contract
3) keeps body temperature steady

23
Q

give 3 examples of large molecules being made from smaller ones?

A

1) lots of glucose molecules are joined together in reactions to form starch
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 turned into proteins

24
Q

give 2 examples of larger molecules being broken down?

A

1) Glucose is broken down in respiration

2) Excess protein is broken down in a reaction to produce urea

25
Q

what is metabolism?

A

the sum of all the chemical reactions in the body

26
Q

what is aerobic respiration?

A

respiring using oxygen

27
Q

where does most aerobic respiration happen?

A

in the mitochondria

28
Q

what is the formula for aerobic respiration?

A

glucose + oxygen –> carbon dioxide + water

C6H12O6 + 6O2 –> 6CO2 + 6H2O

29
Q

what is anaerobic respiration?

A

respiration without oxygen

30
Q

what is the formula for anaerobic respiration?

A

glucose –> lactic acid

31
Q

how do plants respire?

A

without oxygen to produce ethanol

32
Q

what is the formula for respiration in plants?

A

glucose –> ethanol + carbon dioxide

33
Q

what is anaerobic respiration in yeast called?

A

fermentation which is used to produced alcohol

34
Q

what makes bread rise?

A

carbon dioxide

35
Q

what happens when you exercise?

A

1) more contraction of muscles causes you to respire more and therefore you need more oxygen
2) your heart race increases
3) breath volume increases which also helps remove CO2

36
Q

what happens during very vigorous exercise?

A

anaerobic respiration happens and lactic acid is produced

37
Q

after anaerobic respiration what happens?

A

you get oxygen debt which means the amount of oxygen you need to get to react with the lactic acid to remove the lactic acid and produce CO2 and water

38
Q

how can lactic acid be removed?

A
  • through oxygen reacting with it

- blood transports it to the liver where its converted back to glucose

39
Q

how could you measure your pulse?

A 
measure your heart rate when...
-sitting down for 5 mins
-then after 5 mins of gentle walking
-after 5 mins of slow jogging
-then after running for 5 mins
pulse increases with the amount of exercise
40
Q

what can glucose produced from photosynthesis be used for?

A
  • for respiration
  • converted into insoluble starch for storage
  • used to produce fat or oil for storage
  • use to produce cellulose which strengthens the cell wall
  • used to produce amino acids
41
Q

what type of reaction is photosynthesis?

A

endothermic as light energy is transferred from the environment to the chloroplasts by light

42
Q

what is cellular respiration?

A

an exothermic reaction that is constantly occurring in living cells

43
Q

why do organisms need energy?

A
  • chemical reactions to build larger molecules
  • movement
  • to keep warm
44
Q

why is less energy converted in anaerobic respiration?

A

because the oxidation of glucose is incomplete so much less energy is transferred

45
Q

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

A

glucose –> ethanol + carbon dioxide

46
Q

what is respiration in yeast called?

A

fermentation and is important in manufacture of bread and alcohol

47
Q

why does blood flow through muscle?

A

to transport to the liver where it is converted back into glucose

48
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 cells

49
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 molecules of fatty acids
  • the use of glucose and nitrate ions to form amino acid which in turn are used to synthesise proteins
  • respiration
  • breakdown of excess proteins to form urea for excretion

GCSE Biology (4 decks)

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