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IGCSE Biology > 2.24-2.33 Human nutrition > Flashcards

2.24-2.33 Human nutrition Flashcards

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1
Q

What should a balanced diet consist of?

A

Right proportions of carbohydrate, proteins, lipids, vitamins, mineral ions, water and dietary fibre

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2
Q

What are sources and the functions of carbohydrates?

A

Provide energy

Pasta, rice

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3
Q

What are sources and the functions of lipids?

A

Butter, oily fish

Provide energy, act as an energy store and provide insulation and protection

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4
Q

What are sources and the functions of proteins?

A

Meat, fish

Growth and repair of tissue and to provide energy in emergencies

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5
Q

What are sources and the functions of vitamin A?

A

Liver, fish, cheese and eggs

Forms on essential part of the pigment in rods and cones that detect light

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6
Q

What are sources and the functions of vitamin C?

A

Fruit e.g. oranges
Prevent scurvy
Forms an essential part of collagen protein which makes up skin, hair, gums and bones

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7
Q

What are sources and the functions of vitamin D?

A

Egg, fish
Calcium absorption
Regulation the growth of bones
Lack can cause rickets

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8
Q

What are sources and the functions of calcium (mineral ions)?

A

Milk, cheese

Make bones and teeth

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9
Q

What are sources and the functions of iron (mineral ions)?

A

Red meat

Make haemoglobin for healthy blood

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10
Q

What are sources and the functions of water?

A

Food and drink
Replace water lost through urinating, breathing and sweating and solvent for chemical reactions
Haemoglobin

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11
Q

What are sources and the functions of dietary fibre?

A

Wholemeal bread, fruit

Aids the movement of food through the gut

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12
Q

How do energy requirements vary with activity level?

A

More active = Need more energy

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13
Q

How do energy requirements vary with age?

A

Children and teenagers need more to grow and generally more active

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14
Q

How do energy requirements vary with pregnancy?

A

Pregnant women need more energy - provide the energy their babies need to develop

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15
Q

Practical: Investigate the energy content in a food sample

A

1) Find the mass of a small piece of potato using a mass balance
2) Add a 25cm3 of water to a boiling tube held with the a clamp
3) Measure the temperature of the water at the beginning
4) Set fire to the food on a mounted needle using a Bunsen burner flame
5) Hold the food under the boiling tube until it goes out, then relight the food and hold it under the tube repeatedly until the food won’t catch fire again
6) Measure the temperature of the water again
7) Then use the equations

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16
Q

What are the equations for the amount of energy in the food?

A

Energy in food = mass of water x temperature change of water x 4.2
Energy per gram of food = energy in food/mass of food

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17
Q

How would you increase the accuracy for the energy experiment?

A

Insulate the boiling tube to minimise heat loss and keep more energy in the water

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18
Q

What do the digestive enzymes do to big molecules and why?

A

Break them into smaller ones

  • Too big to pass through the walls of the digestive system
  • Insoluble
19
Q

Where is amylase:

a) made
b) work
c) substrate (original molecule)
d) product

A

a) Salivary glands
b) Mouth
c) Starch
d) Maltose

20
Q

Where is protease:

a) made
b) work
c) substrate (original molecule)
d) product

A

a) Stomach cells
b) Stomach
c) Protein
d) Amino acids

21
Q

Where is amylase, protease, lipase:

a) made
b) work
c) substrate (original molecule)
d) product

A

a) Pancreas
b) Small intestine
c) Starch, protein, fat
d) Maltose, amino acids, glycerol and fatty acids

22
Q

Where is maltase, protease:

a) made
b) work
c) substrate (original molecule)
d) product

A

a) small intestine
b) small intestine
c) maltose, protein
d) glucose, amino acids

23
Q

What is chemical digestion?

A

Digestion using enzymes

24
Q

What is mechanical digestion?

A

Digestion by physically breaking food into smaller piece e.g. mouth and teeth chewing food, stomach churning food

25
Q

What is the function of bile? Where is it produced and stored?

A
  • Produced: Liver, Stored: Gall bladder
  • Emulsify lipid (turning fat into tiny droplet) to give a bigger surface for lipid to break it down
  • Alkali, neutralises stomach acid otherwise pH would be too acidic for enzymes in the small intestine (stomach acid kills bacteria in the stomach and maintains optimum pH for pepsin)
26
Q

Alimentary canal: What is the function of the mouth?

A

Salivary glands in the mouth produce amylase enzyme in the saliva
Teeth break down food

26
Q

Alimentary canal: What is the function of the mouth?

A

Salivary glands in the mouth produce amylase enzyme in the saliva
Teeth break down food

27
Q

Alimentary canal: What is the function of the oesophagus?

A

The muscular tube that connects the mouth and stomach

28
Q

Alimentary canal: What is the function of the liver?

A

Where bile is produced

29
Q

Alimentary canal: What is the function of the gall bladder?

A

Bile stored

30
Q

Alimentary canal: What is the function of the large intestine (colon) ?

A

Excess water is absorbed from the food

31
Q

Alimentary canal: What is the function of the stomach?

A

Pummels the food with its muscular walls
Produces pepsin (protease)
Produces hydrochloric acid for two reasons : kill bacteria, give the optimum pH for protease enzyme to work (ph2 - acidic)

31
Q

Alimentary canal: What is the function of the pancreas?

A

Produces protease, amylase and lipase enzymes and releases them into the small intestine

32
Q

Alimentary canal: What is the function of the small intestine?

A

Produces protease, amylase and lipase enzymes to complete digestion
Where the nutrients are absorbed out of the alimentary canal into the body
First part is the duodenum and the last part is the ileum

32
Q

Alimentary canal: What is the function of the small intestine?

A

Produces protease, amylase and lipase enzymes to complete digestion
Where the nutrients are absorbed out of the alimentary canal into the body
First part is the duodenum and the last part is the ileum

33
Q

Alimentary canal: What is the function of the rectum?

A

Last part of the large intestine

Where the faeces are stored before they leave through the anus

34
Q

Define ingestion

A

Taking food into the digestive system

35
Q

Define digestion

A

Breaking food down into molecules small enough to be absorbed into the bloodstream
Mostly in the duodenum - first part of small intestine where a large number of enzymes from the pancreas are mixed with food from the stomach

36
Q

Define absorption

A

Taking molecules into the bloodstream

Mostly in the ileum

37
Q

Define assimilation

A

Using food molecules to build new molecules in our bodies i.e. the food molecule physically becomes part of our body

38
Q

Define egestion

A

Removing unwanted food from the digestive system - not excretion

39
Q

Define peristalsis

A

The circular muscle contractions of the muscular tissue down the alimentary canal behind a bolus of food (ball of food) to push the bolus through the intestine

40
Q

What are the adaptions of the small intestine?

A

Thin wall - speeds the rate of diffusion fo molecules into the blood
Rich blood supply - helps carry absorbed molecules away quickly = always a low concentration of food molecules in the blood, which maintains a high concentration gradient for diffusion
Intestine length - roughly 7m long, increase SA and time to break down and absorb all the food before it reaches the end
Surface area - walls covered in millions of villi and each villus has its own microvilli, villi have a single permeable layer of surface cells and a very good blood supply to assist quick absorption

IGCSE Biology (5 decks)

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