6.1 + 6.2 +6.3

Question 1

define balanced diet (for humans).

Answer 1

a balanced diet is a diet that includes all the nutrients that human cells and tissues use to keep healthy. they include proteins, carbohydrates, fats, vitamins and minerals.

Question 2

describe dietary importance of proteins (and the principal sources)

Answer 2

Principal Sources:
Meat, fish, eggs, soya, milk

Use in the body:

Growth
Tissue repair
Constituents of enzymes, some hormones, antibodies, haemoglobin, hair and nails

proteins are broken down to make amino acids. then the amino acids are used to form other proteins needs by cells including enzymes. they are needed for growth and repair.

Question 3

describe dietary importance of carbohydrates (and the principal sources)

Answer 3

carbs are broken down into simple sugars to use in respiration. it releases energy in our cells and enables life process to take place.

Principal Sources:
Rice, potato, yam, bread, millet

Use in the body:
Gives us short-term energy supply

Question 4

describe dietary importance of fats (and the principal sources)

Answer 4

Principal Sources:
Butter, milk, cheese, egg yolks, groundnuts

Use in the body:
Store of energy to supply molecules for respiration (if the diet doesn’t contain enough energy of the body’s daily needs)
Insulation against heat loss (maintaining body temp)
Constituent of cell membrane and some hormones

Question 5

describe dietary importance of vitamins (and the principal sources)

Answer 5

Vitamins + minerals are needed in tiny amounts for the correct functioning of the body.

VITAMIN C:

Principal Sources:
Citrus fruits, cabbage, tomato, mango
Use in the body:
Needed to make healthy skin and gums

VITAMIN D
Principal Sources:
Milk, cheese, egg yolk, fish liver oil
Use in the body:
Needed to maintain hard bones
Helps in absorption of calcium from the small intestine

Question 6

describe dietary importance of minerals (mineral salts) (and the principal sources)

Answer 6

Vitamins + minerals are needed in tiny amounts for the correct functioning of the body.

CALICUM
Principal Sources:
Milk, cheese, fish
Use in the body:
Needed to form healthy teeth and bones
For normal blood clotting

IRON
Principal Sources:
Red meat, liver, kidney, green vegetables
Use in the body:
Needed for formation of haemoglobin in red blood cells

Question 7

describe dietary importance of fibre (roughage) (and the principal sources)

Answer 7

fibre is made up of the cell walls of plants. it helps move food and feces to our gut.

Principal Sources:
Vegetables, wholemeal bread, fruit

Use in the body:
It adds bulk to food passing through the intestines
Helps to maintain peristalsis

Question 8

describe dietary importance of water (and the principal sources)

Answer 8

water is nessacary for all life processes. it is the major constituent of the body of living organisms

Principal Sources:
Water, food, drinks

Use in the body:
Needed for temperature regulation, chemical reactions and cell life

Question 9

vitamins and minerals…

Answer 9

cannot be produced by the body. some are even destroyed during cooking food.

Question 10

explain how age, gender, and activity affect the dietary needs of humans (ex. during pregnancy and breast-feeding etc)

Answer 10

Different groups of people may have different needs for nutrients at different times in their lives.

Children need a higher proportion of protein than adults because they are still growing.

During pregnancy a woman needs more iron than usual to supply what the growing baby needs for making blood cells.

Question 11

describe the effects of malnutrition (starvation, constipation, coronary heart disease, obesity, and scurvy)

Answer 11

malnutrition: it literally means ‘bad nutrition’. it means any diet that will lead to health problems (like those listed below)

Obesity:
Too much food
Causes heart disease, strokes, diabetes

Coronary Heart Disease:
Too much saturated fat
Cholesterol sticks to the walls of coronary arteries, so not enough blood can get to the heart, leads to heart attack

Starvation:
Too little food
Weight loss, organ damage, death

Constipation:
Lack of fibre
Unable to defecate pain

Scurvy:
Lack of Vitamin C
Bleeding under skin & bleeding gums

Question 12

explain the causes and effects of vitamin D and iron deficiencies.

Answer 12

Iron deficiency causes anaemia. People with anaemia become tired and weak because their blood does not transport enough oxygen.

Vitamin D is needed to maintain healthy bones and teeth. Vitamin D deficiency leads to rickets and bone pain.

Question 13

explain the causes and effects of protein-energy malnutrition (kwashiorkor and marasmus)

Answer 13

Kwashiorkor:
Wrong proportion of nutrients,
e.g. too much carbohydrates (starchy foods) and a lack of protein
kwashiorkor found in young children
referred to as protein energy malnutrition.
lead to the swelling of the feet and abdomen

Marasmus:
Occurs when there is an insufficient energy intake to match the body’s requirements.
As result, the body draws on its own stores, resulting in emaciation.

Question 14

define ingestion

Answer 14

ingestion: the taking of substances (ex. food and drink into the body through the mouth)

Question 15

define digestion

Answer 15

digestion: the breakdown of large, insoluble food molecules into small, water-soluble molecules using mechanical and chemical processes

Question 16

define absorption

Answer 16

absorption: the movement of digested food molecules through the wall of the intestine into the blood

Question 17

define assimilation

Answer 17

assimilation: the movement of digested food molecules into the cells of the body where they are used, becoming part of the cells

Question 18

define egestion

Answer 18

egestion: passing out of food that has not been digested, as feces, through the anus

Question 19

be able to identify the main regions of the alimentary canal and associated organs

Answer 19

see pg 87

Question 20

function of the mouth

Answer 20

the teeth and tongue break down food into smaller pieces

Question 21

function of the slaviary glands

Answer 21

produce liquid saliva which moistness food so it is easily swelled. contains the enzyme amylase to begin the breakdown of starch.

Question 21

function of the oesophagus

Answer 21

each lump of swallowed and chewed food (called a bolus) is moved from the mouth to the stomach via the oesophagus by waves of muscle contraction called peristalsis

Question 22

function of the stomach

Answer 22

acid and protease enzymes are secreted to start proteins digestion; movements of the muscular wall churn up food into a liquid

Question 23

function of the liver

Answer 23

cells in the liver make bile. Digested food is assimilated here. (Excess glucose is removed form the blood and stored as glycogen in liver cells.)

Question 24

function of the gall bladder

Answer 24

Stores bile from the liver. the bile is passed along the bile duct into the small intestine where it neutralizes the stomach acid in the chyme

Question 25

function of the pancreas

Answer 25

Secretes digestive enzymes in an alkaline fluid into the small intestine

Question 26

function of the small intestine

Answer 26

Secretions from the gall bladder and pancreas enter the first part of the small intestine to complete the process of digestion. digested food molecules and water are absorbed in the second part of the small intestine

Question 27

function of the anus

Answer 27

feces are digested through a sphincter

Question 28

define mechanical digestion

Answer 28

the breakdown of food into smaller pieces without chemical change to the food molecules

Question 29

define chemical digestion

Answer 29

the breakdown of large, insoluble molecules into small, soluble molecules

Question 30

identify and describe the types of human teeth (functions)

Answer 30

incisors: At the front of the mouth, chisel shaped, good for biting off food

canines: Four pointed canines pierce and hold food, particularly meat, so that it can be chewed

premolars: Helps with the cutting off of tough foods and grinding of plant material on a small grinding surface

molars: At the back of the mouth, have large grinding surfaces for chewing, particularly plant material

Question 31

describe the structure of human teeth

Answer 31

teeth are made up of enamel, dentine, pulp, nerves, and cement as well as the gums. (see diagrams pg 90)

enamel: bacteria can corrode it. it is hard but still vulnerable to attack by acids. plaque builds on it. it covers the crown.
dentine: can be attacked by bacteria. it is softer than enamel. has a yellow-ish color.
pulp: has nerves. it is exposed when you have a cavity.
nerves: in the pulp. makes us get toothaches and feel sudden heat or coolness, sharp pains.
cement: bone-like material covering the roots
gums: holds the tooth in place

Question 32

state the significance of chemical digestion in the alimentary canal

Answer 32

Because mechanical digestion involves physically breaking down food substances into smaller particles, the role of chemical digestion is to further degrade the molecular structure of the compounds by digestive enzymes into a form that is absorbable into the bloodstream. IT PRODUCES SMALL, SOLUBLE MOLECULES THAT CAN BE ABSORBED

Question 33

state the causes of dental decay (how it happens etc)

Answer 33

Tooth decay is caused by bacteria which grow on teeth. The bacteria make plaque which helps them stick to the teeth. then the bacteria respires in sugars in teh food which produces an acid which dissolves the enamel and dentine. that’s why cavities need to be filled. the pulp will be exposed.

Question 34

state the functions of enzymes amylase, protease, and lipase

Answer 34

amylase: breaks down starch to simpler sugars/glucose (produced in the mouth/salivary glands)
protease: breaks down protein to amino acids (stomach wall)
lipase: breaks down lipids to fatty acids and glycerol

Question 35

where in the alimentary canal are amylase, protease, and lipase secreted?

Answer 35

in the pancreas

Question 36

state and explain the functions of hydrochloric acid in gastric juice

Answer 36

The hydrochloric acid in the gastric juice gives the acid pH for enzymes to work best. The acidic gastric juice also kills bacteria (getting rid of harmful microorganisms in food is important). the acid pH is the optimum pH for protease activity.

Question 37

Outline the role of bile in neutralizing acidic mixture of food and gastric juices entering the duodenum from the stomach, to provide a suitable pH for enzyme action

Answer 37

in the small intestine, the enzymes from the pancreas work better in slightly alkaline conditions. so the acidic food mix has to be neutralized. Bile is highly alkaline so when it is added tot he contents of the small intestine it helps digesting the food flow better. it provides a more suitable pH for enzyme action.

Question 38

Outline the role of bile in emulsifying fats to increase the surface area for the chemical digestion of fat to fatty acids and glycerol by lipase

Answer 38

Bile helps to digest fat by breaking the large drops of fat into very small ones. This makes it easier for lipase to digest them. This is called emulsification and is done by bile salts.

Question 39

Bile is….

Answer 39

Bile is made in the liver, stored in gall bladder and then flows along bile duct into duodenum. Bile does not contain any enzymes

Question 40

Explain the significance of villi in increasing the internal surface area of the small intestine

Answer 40

Villi are finger-like projections that increase the surface area for absorption of small molecules.
The larger the surface area, the faster nutrients can be absorbed.

Question 41

Describe the structure of a villus

Answer 41

They are like lumps on this inside of the small intestine. They are the surface through which food diffuses into the blood stream.
They have very thing walls, only one cell thick, this enables molecules to pass through easily.
They also increase the surface area of the small intestine wall meaning that there is a lot of surface for diffusion to happen through.
On the outside of villi, there are capillaries which pick up the diffused food into the blood stream.

Question 42

Describe the roles of capillaries and lacteals in villi

Answer 42

Villi contains blood capillaries -> Absorbs small molecules such as amino acids and glucose.

Villi contain lacteals, which are part of the lymphatic system -> Absorbs fatty acids and glycerol.

Question 43

microvilli?

Answer 43

Each villus is covered with cells which have even smaller projections on them called microvilli -> This gives inner surface of the small intestine a very large surface area - nutrients can be absorbed even faster.