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Biology 2

Cells

The nucleus is the control centre of all cell activity. The nucleus contains the chromosomes that are important in cell division.

Chemicals outside the nucleus make up the cytoplasm. Cytoplasm is enclosed by a cell membrane that separates the cell from
other cells and surrounding fluids, it…

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Enzymes are proteins made by living organisms that speed up the rate of reactions without losing their properties and becoming a
product. They are catalysts. They can be extracted from organisms and still keep their properties. Enzymes are used in biological
washing powders and in certain food manufacturing processes.

Most…

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Substances enter and leave cells through the cell membrane

Digested food and oxygen are among the essential materials to be taken into cells. Waste products such as carbon dioxide must
be removed. All materials going in or out of the cell must pass the cell membrane. Some molecules can pass…

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Tube 2- filled with distilled water, placed in 5% sucrose solution

Tube 2 will have decreased in mass because there is a lower concentration of water outside the tube. This means that the water
would move from the high concentration to the low concentration through osmosis.

The effects of osmosis…

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Minerals ;
o Iron- liver and read meat- making haemoglobyn
o Calcium- milk and cheese- making teeth and bones
o Sodium- salt ­ proper function of nerves
o Fluoride- milk + toothpaste- hardening tooth enamel.
Roughage (dietary fibre) ­ veg, fruit, cereal ­ keeps everthign flowing smoothly through the digestive…

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Layers of muscle line the walls of the oesophagus, squeezing the food to move to the stomach.

The stomach

Pummels the food with its muscular walls
It has a thick lining with many glands. It twists, squeezes and churns the food.
There are three types of glands secreting; digestive enzymes,…

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We can't break downs cellulose, so we can't put on weight form eating it. We eat veg as the fibre gives your digestive muscles
something to press on to move the food through your body. Otherwise, it would stay in your body and go off.

Enzymes involved in digestion- break…

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Girls generally have a growth spurt before boys (reach puberty first) but growth during puberty is at the same rate for both.

How does growth rate differ with different parts of the body?

Alometric growth.

In a foetus, the brain and head grow quickly then gradually slow down, and the…

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Photosynthesis= carbon doxide + water sunlight + chlorophyll Glucose and oxygen

Energy is released from food and is one of the basic needs of all living things. Energy contained in food is released and used in the
living organism. Therefore, to remain alive, the organism must be supplied with fuel…

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Energy and nutrient transfer

Plants are the first links in all food chains because they are producers- they change the energy in sunlight into stored chemical
energy. When plants are eaten by herbivores, some of the energy is passed to the consumers in the food chain. The energy
passes in…

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