We breathe in and out, or inhale and exhale to ventilate our lungs.

C6H12 O6     6O2                        energy    6CO 2 +H2O

Composition of Air inhaled/exhaled

Inhaled        Exhaled

Oxygen 21%        16%

Carbon Dioxide 0.04%        4%

Nitrogen 78%        78%

Water vapour varies        Saturated

Exhaled air has less oxygen

More carbon dioxide

Is warmer

And wetter

Than inhaled air

Biology

The Skeleton

Functions of the skeleton:

1. Support
2. Movement
3. Protect heart and lungs
4. Make blood cells
5. Calcium storage

Teeth

Humans have 2 sets of teeth, the baby set, deciduous teeth (20). There is the adult set, permanent teeth we have 32.

Above:- diagram of a tooth.

PULP-containing nerves and blood vessels

How to keep your teeth healthy-

1. Clean them at least twice a day.
2. Go to the dentist regularly, (at least every 6 months).
3. Try to avoid too many sugary products e.g. fizzy drinks, sweets.
4. Change your toothbrush every 2 months.
5. Use toothpaste with fluoride.
6.  Where a mouthguard when playing a sport like rugby or hockey.
7. Have a balanced diet.
8. Enough calcium

9. 2-3 minutes brushing.

10. Don’t chew toffees.

Types of teeth

Incisors 2/2-seen from the front have straight top edges. From the side they are chisel shaped.

They are in the front of your mouth and are used for biting.

Canines 1/1- more pointed than incisors. They are next to the incisors the 3rd teeth.

Pre-molars-2/2smaller versions of molars with only 1 root, ribbed teeth.

  Molars3/3-3 roots, bigger and have a flatter surface than incisors. They are at the back, cheek teeth. We use them for chewing and grinding.

Teeth are made up of three layers- enamel, dentine, and pulp cavity. The enamel is the strongest layer.

Plaque-food and bacteria

Bacteria feed on sugar in your mouth, which produces acid, which cause decay. Fluoride helps prevent tooth decay.

If you have gum disease, your gums bleed.

Processing Our Food

Ingestion- putting food in you mouth.

Digestion- the break down of large molecules into small molecules.

Physical chewing, churning

Chemical- enzymes work as catalysts

Absorption- small food molecules passing from the gut into the blood.

Assimilation- how the absorbed food is used in the body.

E.g.- for energy

growth and repair.

Egestion- the passing out of undigested food in the faeces.

Enzymes- are biological catalysts. They speed up reactions. Enzymes are proteins.

Diet

A balanced diet has all the food types in roughly the correct proportions.

Types of food required: -

1. Carbohydrates
2. Protein
3. Fat
4. Vitamins
5. Minerals
6. Water
7. Fibre

Carbohydrates

Carbohydrates contain the elements carbon, hydrogen and oxygen. In the proportions of (CH2O)

E.g. Glucose C6H12O6

Sugar C12H22O11

Starch

Foods that are rich in carbohydrates: -

Potatoes

Pasta

Cereal

Bread

Rice

Carbohydrates are used for energy, we need them for our energy. They can be stored as glycogen, in the liver and muscles or converted to fat and stored under the skin and around body organs.

Properties of Carbohydrates-

Sugar

1. Tastes sweet
2. Soluble in water
3. Doesn’t need to be digested
4. Absorbed directly
5. Quick source of energy
6. Too much sugar leads to tooth decay and obesity, which leads to high blood pressure and heart disease.

Chemical test for sugar (carbohydrate)

1. Put 2ml of sugar solution in a test tube.
2. Put 2ml of Benedict’s solution in with the sugar.
3. Heat in a water bath.
4. Observe the colour change.

It should change colour to orange/red.

Starch (carbohydrate)

1. Starch is a complex carbohydrate.

2. It does not taste sweet.

3. It doesn’t dissolve in water.

1. It was to be digested before being absorbed into the blood.
2. Starch is a storage compound.
3. Common sources of starch in our diet :- rice, bread, potatoes, and pasta.

Chemical test for starch (carbohydrate)

1. Add the iodine solution.
2. Observe the colour change.

Colour change is – red/brown to blue/black

Investigating amylase

Amylase breaks down the starch, so sugar is produced.

Amylase is an enzyme, which breaks down starch.

Protein:

Protein contains the elements; carbon, oxygen. Hydrogen and nitrogen, sometimes sulphur and phosphorous.

Sub units of protein are amino acids.

Foods rich in protein: -

Meat

Fish

Milk

Nuts

Eggs

Cheese

Beans

Use in the body:

Growth

Including renewal of dead cells.

Excess protein-

Can’t be stored

Excess is broken down

Lack of protein-

Kwashiorkor

Chemical test for protein: -

1. The biuret test for protein – add protein to sodium hydroxide solution, add 2 drops of copper sulphate solution, the solution will turn purple if protein is present.

Fat

Fat and oils contain the elements; carbon, hydrogen, and oxygen, but not in set proportions.

Foods high in fat:-

Butter

Chocolate

Lard

Chips

Anything fried

Peanuts

Fatty Meat

Use of fat in the body-

1. Energy
2. Insulation and padding
3. Storage-under the skin around body organs

Excess fat-

Obesity

Heart disease

Diabetes

Lack of fat-

Become thin

Chemical test for fat: -

2. Paper test – put fat or oil onto unglazed paper. If fat is present, the paper becomes translucent.
3. Emulsion test – dissolve fat in alcohol, pour the alcohol into water, an emulsion forms.

Vitamins

Vitamins are needed in very small amounts. They each do a specific job.

E.g., Vitamin C is needed in the gums.

If lacking a deficiency disease occurs.

E.g. If you lack vitamin C you can get scurvy.

Vitamins are found in fresh fruit and vegetables.

Vitamin D-found in butter and egg yolks, can also be made by the skin but only if it is exposed to sunlight.

Deficiency disease is called rickets, this is when you have soft deformed bones.

Minerals

Obtained from a variety of foods, they do particular jobs. If you lack then it causes a deficiency disease.

E.g., Calcium is good for your teeth and bones if lacking you can get rickets, brittle  teeth and bones.

Iron-needed for making haemoglobin for blood cells. Found in liver and egg yolk. Deficiency disease- anaemia.

Salt- necessary to make up for what we loose when sweating. Too much leads to high blood pressure which puts strain on the heart.

Fibre

It is found in:-

All plant food

Fruit

Vegetables

It is composed of cellulose that makes plant cell walls.

It isn’t used by humans but helps stimulate the gut muscles to push the food along. Prevents constipation and bowel cancer.

12 Ways to have a low-fat diet

1. Don’t fry foods. Try stir-frying or grilling so the fat drips off.
2. Cut the fats off meat.
3. Eat low-fat products.
4. Spread butter thinly.
5. Eat fruit for a snack not junk food.
6. Eat fish and chicken instead of red meats
7. Semi or skimmed milk instead of full fat
8. Don’t cook with cream
9. Avoid food like avocados which contain hidden fat

10.Brown Bread instead of white.

11.Cook in veg oil not lard

12.Eat less chocolate

Energy Requirements in a diet: -

The amount of energy needed from a diet depends on:-

1. Job- sedimentary or manual labour
2. Age- growing lots of energy needed.
3. Size- a smaller person needs less energy than a larger person
4. Pregnancy- energy needed for the baby and then for the milk.

We need energy to:

Build new cells

Repair damage cells

Make nerve cells work

Move about

Keep you warm

Drive chemical reactions

Slimming

Body’s use of energy has to be greater than the diet energy intake.

This can be done by reducing energy content, fat or carbohydrates OR more exercise.

PLANTS

Stamen-filament, anther

Sepal-protect flower while its in bud, may fall off.

Ovary (F)- helps dispersal of seed may become a fruit

Petal- attracts insects to help pollination, brightly coloured scented, with nectary at the bottom.

Anther (M)-produces pollen grains, which are very sticky so they can get stuck to insects for pollination, pollen contains the male gamete.

Carpel-stigma, ovule, ovary, style.

Stigma (F)- unsticks pollen form insects-its sticky

Style(F)- pollen makes a pollen tube through the style to react with the ovule

Ovule(F)- female and male gametes fuse, seed produced

Stalk-supports the flower

Reproduction in Plants

Plants may reproduce-

Asexually-e.g. bulbs strawberry runners  tubers as in potatoes.

This method gives genetically identical plants.

Sexually- this involves the production and fusion of gametes (sex cells)

Flowers are the organs used in sexual reproduction.

Male gametes are made in the anther.

Female Gametes are made in the ovules.

Pollination-male gametes are taken from the anther to the stigma in any flower.

A seed contains an embryo plant  food store&seed coat

A fertilized ovule becomes a seed

Conditions needed for germination

1. Water
2. Suitable temperature

3. Oxygen

Dispersal

Seeds are dispersed to-

Avoid competition

Colonise new places

Animal dispersal-

Succulent fruits-fruits are eaten, seeds egested by the animal e.g. strawberries.

Part of the fruit is eaten the rest containing the seed is discarded e.g. peaches.

Hooked fruits, the  fruit hooks on to the fur, feathers or clothes and is discarded elsewhere e.g. gooseberries.

Wind dispersal

Parachute- the fruit acts as a parachute so that the seed is blown in the wind, e.g. dandelion.

Helicopter-winged fruit slows the fall of the seed e.g. sycamore.

Self-Dispersal

Pods containing seeds, dry twist and flick seeds out e.g. peas, gorse

Water Dispersal

Fruits that float e.g. coconut, water lily.

Differences between wind pollinated and insect pollinated plants.