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IGCSE Biology > II: 6.1 - Nutrients > Flashcards

II: 6.1 - Nutrients Flashcards

1
Q

Define

nutrition

A

The taking in of nutrients which are organic substances and mineral ions, containing raw materials or energy for growth and tissue repair, absorbing and assimilating them.

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2
Q

List the seven types of nutrients

A
  • Carbohydrates
  • Proteins
  • Fats
  • Vitamins
  • Minerals
  • Roughages
  • Water
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3
Q

Carbohydrates:

  1. Chemical elements
  2. Functions/uses
  3. Sources
A
  1. Made up of carbon (C), hydrogen (H) and oxygen (O)
  2. Functions/uses:
    • immediate energy source
    • converted into fat for stored energy
    • in animals, converted into glycogen for storage in liver and muscles
    • in plants, converted into starch for storage
    • cellulose used as dietary fibre (roughage)
    • cellulose makes cell walls
  3. Pasta, grains, bread, fruit, cake, fish (most foods)
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4
Q

Name the deficiency disease for carbohydrates and describe its symptoms.

A

Marasmus

  • grossly underweight
  • little to no body fat
  • muscle wasting
  • old man’s face
  • no oedema
  • lethargy
  • delayed wound healing
  • normal hair
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5
Q

What are the three types of carbohydrates?

A
  1. Monosaccharides
  2. Disaccharides
  3. Polysaccharides
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6
Q

State the characteristics, examples and sources of monosaccharides

A
  • The smallest and simplest form
  • Water soluble
  • Chemical formula: C6H12O6
  • Examples: Glucose, Fructose, Galactose
    • they have the same chemical formula but different structures
  • Sources: Fruits, Honey
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7
Q

State the characteristics, examples and sources of disaccharides

A
  • Each molecule consists of two monosaccharides joined together
  • Water soluble
  • Examples: Lactose, Sucrose, Maltose
  • Sources: Table sugar, Milk
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8
Q

State the characteristics, examples and sources of polysaccharides

A
  • Each molecule has many joined monosaccharide forming a long chain.
  • Insoluble in water
  • Examples: starch, glycogen, cellulose
  • Sources: bread, potatoes, pasta, cellulose in plant cells and glycogen in livers.
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9
Q

Fats (lipids):

  1. Chemical elements
  2. Functions/uses
  3. Sources
A
  1. Made of carbon (C), hydrogen (H) and oxygen (O)
    • the ratio of hydrogen to oxygen is greater than 2:1
    • made up of glycerol and fatty acids
  2. Functions/uses:
    • making cell membranes
    • stored in adipose layer for insulation
    • absorbs mechanical shock around vital organs
    • long-term energy storage (better than glycogen)
    • dissolves certain vitamins
    • gives energy in respiration (twice as much as carbohydrates)
  3. Sunflower oil, palm oil, meat, dairy products, seeds
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10
Q

Name some problems linked with fat deficiency, and some symptoms of the deficiency of essential fatty acids.

A
  • Problems linked with fat deficiency
    • neurological derangement
    • mental illness
    • cardiovascular disease
    • cancer
  • Symptoms of the deficiency of essential fatty acids
    • achy joints
    • brittle nails
    • coarse, unruly hair
    • cold intolerance symptoms
    • constipation
    • cracked skin on heels
    • eczema
    • excessive thirst
    • frequent urination
    • irregular bowel movement
    • low concentration
    • low body weight
    • patches of dry skin
    • poor memory
    • suicidal tendency
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11
Q

What are two types of fats, and how do they differ?

A
  1. Hard fats (saturated) (animal fat)
    • fatty acids have single bonds between all carbon pairs
  2. Oils (unsaturated) (plant oils)
    • fatty acids contain double bonds between one or more carbon pairs
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12
Q

Proteins:

  1. Chemical elements
  2. Functions/uses
  3. Sources
A
  1. Made up of carbon (C), hydrogen (H), oxygen (O) and nitrogen (N)
  2. Functions/uses:
    1. Growth
    2. Repair
    3. Synthesis of hormones, enzymes, cells, antibodies, and blood proteins (in plasma)
  3. Meats, dairy products, seeds, pulses
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13
Q

Name the deficiency disease for proteins, and describe its symptoms.

A

Kwashiorkor

  • Changes in hair texture/colour
  • large belly that sticks out
  • loss of muscle mass
  • changes in skin pigment
  • oedema and rash
  • lethargy
  • failure to gain weight and grow
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14
Q

How are proteins structured?

A
  • Building blocks: amino acids
  • Around known types of amino acid exist
  • Amino acids linked together by peptide bonds
  • One protein molecule (polypeptide) is made up of about 50 amino acids
  • Two joined amino acids - dipeptide, three - tripeptide
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15
Q

Vitamin C (ascorbic acid)

  1. Functions/uses
  2. Sources
A
  1. Functions/uses:
    • essential for the formation of collagen, a protein that functions as cementing layer between cells
    • therefore used for healing wounds, strong skin & blood vessels
    • increases immunity
  2. This is present in most fruits and vegetables specially citrus fruits like lemon and oranges; however, it is damaged by heating

Vitamin C cannot be stored in the body; daily intake is needed

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16
Q

Name the deficiency disease for vitamin C, and describe its symptoms.

A

Scurvy

  • bleeding and swelling of the gums
  • loss of teeth
  • tiredness
  • muscle and joint pain
17
Q

Vitamin D (calciferol)

  1. Functions/uses
  2. Sources
A
  1. Promotes absorption of calcium & phosphate from intestine, ensures they are deposited in bones
  2. Sources
    • found in cheese, margerine, butter, milk healthy cereals, fatty fish
    • made by animals as well as plants (this occurs when the skin is exposed to the UV rays of the sun; natural fats in the skin are converted to a form of calciferol by sunlight)
18
Q

Name the deficiency disease for vitamin D, and describe its symptoms.

A

Rickets (in young children)

  • soft bones
  • bowed legs

Osteomalacia (in adults)

19
Q

Calcium

  1. Functions/uses
  2. Sources
A
  1. Functions/uses:
    • needed for the formation of bones and teeth as they are made of calcium salts (phosphate)
    • present in blood plasma, helps in blood clotting
    • transmission of nerve impulses
  2. dairy products, green leafy vegetables, hard water, salmon, sardines
20
Q

Name the deficiency disease for calcium, and describe its symptoms.

A

Oesteoporosis

  • back pain
  • loss of height over time
  • stooped posture
  • bone fractures occur easily
21
Q

Iron

  1. Functions/uses
  2. Sources
A
  1. formation of the red pigment haemoglobin which is essential for the transport of oxygen around the body in red blood cells
  2. red meat, green leafy vegetables, oysters, legumes, egg yolk, artichoke, scallops
22
Q

Name the deficiency disease for iron, and describe its symptoms.

A

Anaemia

  • fatigue
  • dizziness
  • easily becoming breathless
  • paleness
23
Q

Fibre

  1. Functions/uses
  2. Sources
A
  1. Used by alimentary canal to keep muscles working, i.e. it promotes peristalsis
  2. Fruits, vegetables, unrefined rice, wholegrains
24
Q

What problems may arise due to a deficiency of fibre?

A
  • constipation
  • bowel cancer
25
Q

List the functions/uses of water

A
  • transport of nutrients
  • transport of waste
  • universal solvent
  • breakdown of food (hydrolysis)
  • cooling the body
  • chemical medium for reactions
26
Q

Describe the food test and results for starch

A
  • Test: add a few drops of iodine
  • Positive result: turns blue-black
  • Negative result: stays orange/yellow
27
Q

Describe the food test and results for reducing sugars (e.g. glucose)

A
  • Test: Add an equal volume of Benedict’s solution and heat in a water bath for 3 minutes
  • Postive result: Turns green/yellow/orange/brown/brick-red
  • Negative result: Stays blue
28
Q

Describe the food test and results for non-reducing sugars (e.g. sucrose, fructose)

A
  • Test:
    • add 1 cm3 of HCl and heat in a water bath for 3 minutes
    • after cooling, add 1 cm3 NaOH to neutralise
    • proceed with reducing sugars test
  • Positive result: Turns green/yellow/orange/brown/brick-red
  • Negative result: Stays blue
29
Q

Describe the food test and results for protein

A
  • Test: add Biuret solution (1 cm3 NaOH to a few drops of copper sulphate CuSO4)
  • Positive result: Turns pink/lilac/purple
  • Negative result: Stays blue
30
Q

Describe the food test and results for fat

A
  • Test:
    • add 2cm3 of ethanol, shake, then allow to settle for 2 minutes
    • pour clear liquid into 2cm3 of disitilled water
  • Positive result: Turns cloudy
  • Negative result: Stays clear
31
Q

Describe the use of microorganisms in the food industry, with reference to yoghurts and single cell proteins

A

Yoghurt

  • Soured milk, partially clotted, with a mildly acidic taste.
  • In incubation, culture of bacteria are kept at 45°C and turn lactose into lactic acid during respiration, then cooling at 4°C stops reaction

Single cell proteins

  • Sources of mixed protein extracted from pure or mixed cultures of algae, yeasts, fungi or bacteria (grown on agricultural wastes)
  • Used as a substitute for protein-rich foods, for humans & animals
  • Excess yeast from alcoholic fermentation is sometimes used as cattle feed.
32
Q

Describe the uses, benefits and health hazards associated with food additives, including colourings.

A
  • Substances with no nutrient value which are added to improve appearance, flavor, texture and/or storage properties of food
  • Preservatives inhibit growth of fungi/bacteria e.g. SO2 to control browning of potatoes and anti-oxidants prevent deterioration.
  • Food additives can have health hazards, e.g. sulfur dioxide causes sensitivity in asthma sufferers.

IGCSE Biology (24 decks)

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