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IGCSE Biology Specification > Structure and Functions in Living Organisms - Nutrition > Flashcards

Structure and Functions in Living Organisms - Nutrition Flashcards

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1
Q

what is photosynthesis?

A

Production of Glucose in plant cells using light energy from the Sun

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2
Q

what is the equation for photosynthesis?

A

Carbon Dioxide + Water → Glucose + Oxygen

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3
Q

what happens during photosynthesis?

A
  • Light energy from the sun is absorbed by chlorophyll to produce glucose which is stored as starch for growth, and oxygen as a waste product
  • Glucose produced in photosynthesis is passed down the food chain from one organism to another
  • Photosynthesis only occurs under the presence of sunlight
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4
Q

what factors affect the rate of photosynthesis?

A

carbon dioxide concentration, light intensity and temperature

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5
Q

how does carbon dioxide concentration affect the rate of photosynthesis?

A
  • As the concentration of carbon dioxide increases, the rate of photosynthesis will increase
  • Carbon dioxide is a reactant in photosynthesis, an increase in concentration will allow more photosynthesis to occur
  • However, as the concentration increases beyond a certain point, the rate of photosynthesis with plateau as another factor will be the limiting factor
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6
Q

how does temperature affect the rate of photosynthesis?

A
  • As temperature increases towards optimum, the rate will increase
  • This is because the increase in temperature towards optimum will allow optimum enzyme activity
  • However, as temperature increases above optimum, enzymes involved in Photosynthesis will denature, therefore causing so rate decreases
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7
Q

how does light intensity affect the rate of photosynthesis?

A
  • As light intensity increases, the rate will increase
  • Photosynthesis can only occur under the presence of light, an increase in light intensity will therefore allow more Photosynthesis to occur
  • However, as light intensity increases beyond a certain point, the rate will plateau as another factor is the limiting factor
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8
Q

what are the layers of a leaf?

A

waxy cuticle, upper epidermis, palisade mesophyll, spongy mesophyll, lower epidermis

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9
Q

what is the waxy cuticle?

A

The outermost protective layer that prevents water loss via evaporation

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10
Q

what is the upper epidermis?

A

A thin and transparent layer of cells that allows light to enter palisade mesophyll

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11
Q

what is the palisade mesophyll?

A

Layer tightly packed with chloroplasts to maximise light absorption for photosynthesis

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12
Q

what is the spongy mesophyll?

A

Layer containing internal air spaces to increase surface area to volume ratio for the diffusion of gases

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13
Q

what is the lower epidermis?

A

Layer containing:
- Guard cells: cells that control the opening and closing of stomata by absorbing and losing water to regulate gas exchange and prevent water loss
- Stomata: mouth-shaped opening controlled by guard cells

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14
Q

how is the leaf adapted for photosynthesis?

A
  • large surface area
  • thin
  • a large amount of chlorophyll
  • a large network of veins
  • stomata
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15
Q

how does the large surface area of a leaf increase the rate of photosynthesis?

A

Increases surface area to volume ratio for diffusion

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16
Q

how does the thinness of a leaf increase the rate of photosynthesis?

A

Short diffusion length which increases the rate of diffusion

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17
Q

how does the large amount of chlorophyll increase the rate of photosynthesis?

A

present in large amounts in the palisade mesophyll to maximise light absorption

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18
Q

how does the large network of veins increase the rate of photosynthesis?

A
  • supports the leaf
  • transports water for photosynthesis and transpiration (via Xylem)
  • transports carbohydrates produced by Photosynthesis (via Phloem)
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19
Q

how do the stomata increase the rate of photosynthesis?

A

Regulates gas exchange by allowing carbon dioxide to diffuse into the leaf for use and Oxygen to diffuse out as a waste product

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20
Q

what mineral ions do plants require for growth?

A

magnesium ions and nitrate ions

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21
Q

what do magnesium ions do in plants?

A

to build chlorophyll for growth
when plants are magnesium deficient leaves turn yellow

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22
Q

what do nitrate ions do in plants?

A

to produce Amino acids to build Protein and DNA
when plants are nitrate deficient eaves turn yellow and stunted growth

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23
Q

how would you investigate the effect of light intensity on photosynthesis in pondweed?

A
  • place pondweed in a beaker of water
  • change the light intensity
  • leave for 5 minutes to allow pond weed to adapt to the environment
  • count the number of air bubbles produced in a fixed period of time
  • increase or decrease the light intensity by a fixed increment
  • repeat process to obtain a range of data
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24
Q

what does a balanced diet consist of?

A

appropriate proportions of carbohydrates, proteins, lipids, vitamins, minerals, water and dietary fibre

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25
Q

what are carbohydrates found in?

A

pasta, rice, sugar

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26
Q

what are the functions of carbohydrates?

A

provide energy

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27
Q

what are lipids found in?

A

butter, oily fish

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28
Q

what are the functions of lipids?

A

provide energy, act as an energy source and provide insulation

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29
Q

what are proteins found in?

A

meat and fish

30
Q

what are the functions of proteins?

A

growth and repair and to provide an emergency energy store

31
Q

what is vitamin A found in?

A

liver

32
Q

what is the function of vitamin A?

A

helps to improve vision

33
Q

what is vitamin C found in?

A

fruit, e.g. oranges

34
Q

what is the function of vitamin C?

A

needed to prevent scurvy

35
Q

what is vitamin D found in?

A

eggs

36
Q

what is the function of vitamin D?

A

needed for calcium absorption

37
Q

what is calcium found in?

A

milk, cheese

38
Q

what is the function of calcium?

A

needed to make bones and teeth

39
Q

what is iron found in?

A

red meat

40
Q

what is the function of iron?

A

needed to make haemoglobin for healthy blood

41
Q

what is water found in?

A

food and drink

42
Q

what is the function of water?

A

to replace water lost through urinating, breathing and sweating

43
Q

what is fibre found in?

A

wholemeal bread and fruit

44
Q

what is the function of fibre?

A

aids the movement of food through the gut (peristalsis)

45
Q

how does activity level affect energy requirements?

A

more active people need more energy

46
Q

how does age affect energy requirements?

A

children and teens need more energy as they need energy to grow

47
Q

how does pregnancy affect energy requirements?

A

pregnant women need more energy to provide the energy their babies need to develop

48
Q

what does the alimentary canal contain?

A

mouth, oesophagus, stomach, small intestine (duodenum and ileum), large intestine
(colon and rectum) and pancreas

49
Q

what happens in the mouth?

A
  1. salivary glands in the mouth produce amylase enzymes in the saliva
  2. teeth break down food
50
Q

what is the oesophagus?

A

the muscular tube that connects the mouth and the stomach

51
Q

what happens in the liver?

A

bile is produced

52
Q

what happens in the gallbladder?

A

bile is stored

53
Q

what happens in the large intestine?

A

excess water is absorbed from food

54
Q

what is the rectum and what happens in it?

A
  1. the last part of the large intestine
  2. where faeces are stored before they leave through the anus
55
Q

what happens in the stomach?

A
  1. food is pummeled with the stomachs walls
  2. produces the protease enzyme, pepsin
  3. produces HCl to kill bacteria and to give the optimum pH for the protease enzyme
56
Q

what happens in the pancreas?

A

produces protease, amylase and lipase enzymes. it releases them into the small enzyme

57
Q

what happens in the small intestine?

A
  1. produces protease, amylase and lipase enzymes to complete digestion
  2. this is where nutrients are absorbed out of the alimentary canal into the body
58
Q

what are the two parts of the small intestine?

A
  1. duodenum
  2. ileum
59
Q

what is peristalsis?

A

wave-like muscle contractions that push food bolus down the oesophagus from mouth to anus - occurs in stomach and gut

60
Q

what is the purpose of peristalsis?

A
  • as food bolus is pushed only a few centimetres at a time, progression through the intestine is slow, allowing time for digestion
  • this allows the churning of semi-digested food as they mix food bolus with enzymes, increasing the rate of digestion
61
Q

what does amylase do?

A

digest starch into maltose

62
Q

what does maltase do?

A

digest maltose into glucose

63
Q

what does protease do?

A

digest protein into amino acids

64
Q

what does lipase do?

A

digest lipids into fatty acids and glycerol

65
Q

where is bile produced?

A

in the liver

66
Q

where is bile stored?

A

in the gallbladder

67
Q

what are the functions of bile?

A
  1. neutralising stomach acid:
    - enzymes in the small intestine function optimally in alkaline conditions
    - the churning of food in the stomach by hydrochloric acid creates an acidic environment
    - bile will neutralise hydrochloric acid to maintain alkaline conditions
  2. emulsifying lipids
    - the breakdown and digestion of lipid molecules require a long period of time, bile is used to emulsify large lipid molecules into small droplets
    - lipid droplets will have a larger surface area to volume ratio, allowing faster breakdown
68
Q

how are the villi adapted for absorption?

A
  • thin cell wall
  • larger surface area to volume ratio
  • dense capillary network
69
Q

how do thin cell walls help the villis absorption?

A

thin cell wall (one cell thick) to minimise the distance of diffusion

70
Q

how does the large surface area of a villi help absorption?

A

increase surface area to volume ratio for the diffusion

71
Q

how does the dense capillary network of a villi help absorption?

A

a dense capillary network provides a rich blood supply, creating a strong concentration gradient for the diffusion

IGCSE Biology Specification (35 decks)

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