Term 3a

Question 1

What are the necessary key food groups?

Answer 1

Carbohydrates
Proteins
Lipids
Dietary fibre
Vitamins
Minerals (mineral ions)
Water

Question 2

Function and source carbohydrates

Answer 2

Function: source of energy
Sources: bread, cereals, pasta, rice, potatoes

Question 3

Function and source protein

Answer 3

Function: growth and repair
Sources: meat, fish, eggs, pulses, nuts

Question 4

Function and source lipids

Answer 4

Function: insulation and energy storage
Sources: butter, oil, nuts

Question 5

Function and source dietary fibre

Answer 5

Function: provides bulk (roughage) for the intestine to push food through it
Sources: vegetables, whole grains

Question 6

Function and source Vitamins and minerals

Answer 6

Function: needed in small quantities to maintain health Sources: fruits and vegetables, meats, dairy products

Question 7

Function and source water

Answer 7

Function: needed for chemical reactions to take place in the body
Sources: water, juice, milk, fruits and vegetables

Question 8

Function and source calcium

Answer 8

Calcium is needed for strong teeth and bones and is involved in the clotting of blood
A deficiency can lead to osteoporosis later in life
It is found in milk, cheese, and eggs

Question 9

Function and source vitamin D

Answer 9

Vitamin D helps the body to absorb calcium and is required for strong bones and teeth
It can be found in oily fish and dairy products, and is also made naturally by the body in sunlight

Question 10

Function and source vitamin C

Answer 10

Vitamin C forms an essential part of collagen protein, which makes up the skin, hair, gums, and bones
A deficiency can cause scurvy. It is found in citrus fruits and some green vegetables

Question 11

Function and source vitamin A

Answer 11

Vitamin A is needed to make the pigment in the retina for vision
It can be found in meat, liver, dairy, leafy green vegetables like spinach, and eggs

Question 12

Function and source Iron

Answer 12

Iron is needed to make haemoglobin, the pigment in red blood cells that helps to carry oxygen
It can be found in red meat, liver, leafy green vegetables, and spinach

Question 13

Energy requirements for young people

Answer 13

The amount of energy that young people need increases towards adulthood as this energy is needed for growth. Children need a higher proportion of protein in their diet than adults as this is required for growth

Question 14

Energy requirements for more active people

Answer 14

The more active, the more energy required for movement as muscles are contracting more and respiring faster

Question 15

Energy requirements for pregnancy

Answer 15

During pregnancy, energy requirements increase as energy is needed to support the growth of the developing fetus, as well as the larger mass that the mother needs to carry around. Extra calcium and iron are also needed in the diet to help build the bones, teeth, and blood of the fetus

Question 16

Energy requirements for male

Answer 16

Male average energy requirements tend to exceed that of females due to them having a larger proportion of muscle compared to fat

Question 17

Energy requirements for breastfeeding mothers

Answer 17

For breastfeeding mothers, energy requirements increase and extra calcium is still needed to make high-quality breast milk

Question 18

What is digestion

Answer 18

Digestion is a process in which relatively large, insoluble molecules in food (such as starch, proteins) are broken down into smaller, soluble molecules that can be absorbed into the bloodstream and delivered to cells in the body

Question 19

What is the alimentary canal

Answer 19

The alimentary canal is the channel or passage through which food flows through the body, starting at the mouth and ending at the anus

Question 20

Function of mouth/salivary glands

Answer 20

Mechanical digestion: teeth chew food to break it into smaller pieces and increase its surface area to volume ratio

Chemical digestion: amylase enzymes in saliva start digesting starch into maltose

The food is shaped into a bolus (ball) and lubricated by saliva so it can be swallowed easily

Question 21

Function of Oesophagus

Answer 21

The tube that connects the mouth to the stomach

Wave-like contractions take place to push the food bolus down without relying on gravity

Question 22

Function of stomach

Answer 22

Food is mechanically digested by churning actions while protease enzymes start to chemically digest proteins.

Hydrochloric acid is present to kill bacteria in food and provide the optimum pH for protease enzymes to work.

Question 23

Function of large intestine

Answer 23

Water is absorbed from the remaining material in the colon to produce faeces

Faeces are stored in the rectum and exit the body via the anus

Question 24

Function of pancreas

Answer 24

Produces all three types of digestive enzymes: amylase, protease and lipase

Secretes enzymes in an alkaline fluid into the duodenum for digestion; this raises the pH of fluid coming out of the stomach

Question 25

The process of Peristalsis

Answer 25

Peristalsis is a mechanism that helps moves food along the alimentary canal Firstly, muscles in the walls of the oesophagus create waves of contractions which force the bolus along Once the bolus has reached the stomach, it is churned into a less solid form, called chyme, which continues on to the small intestine Peristalsis is controlled by circular and longitudinal muscles Circular muscles contract to reduce the diameter of the lumen of the oesophagus or small intestine Longitudinal muscles contract to reduce the length of that section the oesophagus or the small intestine Mucus is produced to continually lubricate the food mass and reduce friction Dietary fibre provides the roughage required for the muscles to push against during peristalsis

Question 26

Digestive enzymes: Carbohydrases and what they do?

Answer 26

Carbohydrases are enzymes that break down carbohydrates to simple sugars such as glucose Amylase is a carbohydrase which breaks down starch into maltose Amylase is made in the salivary glands, the pancreas and the small intestine Amylase from the salivary glands gets denatured in the stomach acid and must be replaced by amylase from the pancreas in the small intestine Maltase then breaks down maltose into glucose

Question 27

Digestive enzymes: Proteases and what they do?

Answer 27

Proteases are a group of enzymes that break down proteins into amino acids Pepsin is an enzyme made in the stomach which breaks down proteins into smaller polypeptide chains Protease enzymes made in the pancreas and small intestine break the polypeptide chains into amino acids

Question 28

Digestive enzymes: Lipases and what they do?

Answer 28

Lipases are enzymes that break down lipids (fats) to glycerol and fatty acids Lipase enzymes are produced in the pancreas and secreted into the small intestine

Question 29

Function of small intestine

Answer 29

The first section is called the duodenum; this is where digestion of the food exiting the stomach is completed by enzymes that are present in the duodenum lining and secreted by the pancreas The pH of the small intestine is slightly alkaline; around pH 8-9. The second section is called the ileum and is where the absorption of water and digested food molecules takes place; the ileum is long and lined with villi to increase the surface area over which absorption can take place

Question 30

Bile production and storage

Answer 30

Bile is an alkaline substance produced by cells in the liver Before being released into the small intestine, bile is stored in the gall bladder

Question 31

The role of bile

Answer 31

Neutralising the hydrochloric acid from the stomach The alkaline properties of bile allow for this to occur This neutralisation is essential as enzymes in the small intestine have a higher (more alkaline) optimum pH than those in the stomach Breaking apart large drops of lipids (fats) into smaller ones (and so increasing their surface area) This is known as emulsification The more alkaline conditions and larger surface area allows lipase to chemically break down the lipid molecules into glycerol and fatty acids at a faster rate

Question 32

Adaptations of the small intestine

Answer 32

The small intestine is adapted for absorption as it is very long and has a highly folded surface with millions of villi (tiny, finger-like projections) These adaptations massively increase the surface area of the small intestine, allowing absorption to take place faster and more efficiently Peristalsis helps by mixing together food and enzymes and by keeping things moving along the alimentary canal

Question 33

Villi of the small intestine

Answer 33

Villi have several specific adaptations which allow for the rapid absorption of substances, such as: A large surface area Microvilli on the surface of the villus further increase the surface available for absorption A short diffusion distance The wall of a villus is only one cell thick A steep concentration gradient The villi are well supplied with a network of blood capillaries that transport glucose and amino acids away from the small intestine in the blood A lacteal (lymph vessel) runs through the centre of the villus to transport fatty acids and glycerol away from the small intestine in the lymph Enzymes produced in the walls of the villi assist with chemical digestion The movement of villi helps to move food along and mix it with the enzymes present

Question 33

The structure of thorax

Answer 33

the ribs intercostal muscles diaphragm trachea bronchi bronchioles alveoli pleural membranes

Question 34

How are alveoli adapted for gas exchange

Answer 34

There are many rounded alveolar sacs which give a very large surface area to volume ratio Alveoli (and the capillaries around them) have thin, single layers of cells to minimise diffusion distance Ventilation maintains high levels of oxygen and low levels of carbon dioxide in the alveolar air space, meaning there is a steep concentration gradient for diffusion of gases A good blood supply ensures a constant supply of blood high in carbon dioxide and low in oxygen, again to maintain concentration gradients for diffusion A layer of moisture on the surface of the alveoli helps diffusion as gases dissolve