Biology - Term 1

Nutrients

Substances in food that your body needs to grow and to supply you with energy

Carbohydrates

To provide energy - cereals, bread, pasta

Protein

For growth and repair - fish, meat, beans

Lipids (fats and oils)

To provide/insulate the body against the cold - Butter, oil, nuts

Minerals

Needed in small amounts to maintain health - salt, milk, liver

Vitamins

Needed in sall amounts to maintain health - fruits, vegetables, dairy foods

Dietary fibre

To provide roughage to help to keep the food moving through the gut - vegetables and barn

Water

Needed for cells and body fluids - water, milk, juice

Obesity

involves a person carrying too much body fat

Anorexia nervosa

an eating disorder which stems from inabality to cope with worries or problems
symptoms: wight loss, dizziness, stomach pains

Bullimia nervosa

an eating disorder thats is a hidden illness because people usually remain average or just over average body weight
symptoms: sore throat, dehydration, dry skin

Vitamin A

Uses: Healthy eyes and skin
Foods dound in: Liver, butter, green vegetables
Deficiency disease: Night blindness

Vitamin B1

Uses: Helps in respiration
Foods found in: wheat, rice
Deficiency disease: Beri Beri

Vitamin B3

Uses: Helps in chemical reactions in the body
Foods found in: yeast, wholemeal bread
Deficiency disease: Pellagra

Vitamin C

Uses: Healthy gums and skin
Foods found in: Citrus fruits, tomatoes, kiwi
Deficiency disease: Scurvy

Vitamin D

Uses: Helps absorb calcium in the body
Foods found in: butter, milk, cheese and made by the sunlight
Deficiency disease: Rickets

Beri Beri

Difficulty walking. Loss of feeling (sensation) in hands and feet.
Loss of muscle function or paralysis of the lower legs.

Kwashiorkor

Being severly underweight, decreased muscle mass, swollen stomach

Pellagra

Skin lesions ( cuts that wont heal), rashes and diarrohea may occur

Rickets

It causes failure of bones to calcify (become hard with calcium)

Scurvy

It results in bleeding gums, poor healing of wounds, teeth falling out, heart failure and anaemia

Calcium

Function: For healthy bones and teeth
Food source: Milk, cheese, bread

Sodium

Function: Needed for muscle and nerve action
Food source: Table salt

Iron

Function: To make haemoglobin for red blood cells
Food source: egg yolk, green leafy vegetables

Fluoride

Function: Needed for healthy enamel and bones
Food source: Water

Potential energy

Stored energy

Starch test

Iodine solution
Orange to blue-black

Reducing sugar test

Heat with Benedict's reagent
Blue to orange - red

Protein test

Biuret reagent
blue to purple

Lipids (Fats) Test

Ethanol solution
colourless to cloudy white

Incisors

front teeth used for cutting food into small pieces
8 incisors in the adult mouth

Canines

in the corner of the dental arc and used to grip and tear food
4 canines in the adult mouth

Pre-molars

to tear and crush food
8 premolars in the adult mouth

Molars

Back teeth that crush and grind food
12 molars in the adult mouth

Enamel

is the outer coat and hardest substance in the body

Dentine

is a hard substance under the enamel layer

Pulp cavity

contains blood vessels and nerves

Fibres

hold the tooth in the jaw bone

Tooth decay

plaque forms a white soft, substance around the gum and between the teeth

Ingestion

This is the process of taking in food substances through the mouth

Digestion

The breaking down of large insolube molecules to small soluble molecules by chemical or mechanical means

Absorption

taking small soluble food molecules into the blood to be transported to the cells

Assimilation

This is the movement of digested food molecules into the cells where they are used

Egestion

This is the process where solid undigested food material is removed via the anus

Mechanical

Food is broken down into smaller pieces - not chemically changed

Chemical

Food is chemically changed

Mouth

Mechanical digestion: Teeth chew food
Chemical digestion: salivary glands contain enzymes (amylase)

Oesophagus (gullet)

passes food down from the mouth to the stomach by a process called perisalsis

Perisatalsis

Rings of muscle around the oesophagus - squeeze the food towards the stomach

Stomach

Mechanical digestion: stomach muscles churn up the food
Chemical digestion: the enzyme pepsin starts to break down protein

Stomach acid

it kills microbes on food
it provides the ideal pH for the enzyme (pepsin) to work in

Pancreas

Produces many enzymes involved in digestion

Small intestine

Can be over 6 metres long
It helps to further digest food coming from the stomach by absorption

Adaptations of small intestine

1. Folded into Villi - increase surface area
2. Good blood supply - to take food that has been absorbed
3. Thin wall - so diffusion happens faster

Large intestine

absorbs water and processes faeces

Liver

produces bile

gall bladder

stores bile

pancreas

produces pancreatic juices

rectum

stores solid waste

anus

releases waste

formula for measuring energy

mass of water x temeprature rise x 4.2 = energy content in J/g