nucleus contains genetic material, which controls the activities of the cell cytoplasm most chemical processes take place here, controlled by enzymes cell membrane controls the movement of substances into and out of the cell mitochondria most energy is released by respiration here ribosomes protein synthesis happens here

nucleus contains genetic material, which controls the activities of the cell cytoplasm most chemical processes take place here, controlled by enzymes cell membrane controls the movement of substances into and out of the cell mitochondria most energy is released by respiration here ribosomes protein synthesis happens here cell wall strengthens the cell chloroplasts contain chlorophyll, which absorbs light energy for photosynthesis

CellFunctionAdaption

Leaf cell

Absorbs light energy for photosynthesis Packed with chloroplasts. Regular shaped, closely packed cells form a continuous layer for efficient absorption of sunlight.

Root hair cell

Absorbs water and mineral ions from the soil Long 'finger-like' process with very thin wall, which gives a large surface area.

Sperm cell

Fertilises an egg cell - female gamete The head contains genetic information and an enzyme to help penetrate the egg cell membrane. The middle section is packed with mitochondria for energy. The tail moves the sperm to the egg.

Red blood cells

Contain haemoglobin to carry oxygen to the cells. Thin outer membrane to let oxygen diffuse through easily. Shape increases the surface area to allow more oxygen to be absorbed efficiently. No nucleus, so the whole cell is full of haemoglobin.

Everything is made from atoms, and there are over 100 different types. These are called elements, and they can be divided into the metals and the non-metals. We'll look at their physical and chemical properties in this Revision Bite.

elements:

There are over a hundred different types of atom, and these are called elements. Each element has a special name. For example carbon, oxygen and hydrogen are all elements.

Lead and gold are elements too. A piece of pure gold contains only gold atoms. A piece of pure lead contains only lead atoms.

Chemical reactions join or split atoms to rearrange them. But they cannot change one element into another element, or anything simpler. A chemical reaction cannot turn lead into gold, becuse it can't change the atoms into different elements.

All the different elements are arranged in a chart called the periodic table.

• The horizontal rows are called periods.

• The vertical columns are called groups.

• Elements in the same group are similar to each other.

• The metals are on the left and the non-metals are on the right.

• One non-metal, hydrogen, is often put in the middle.

• The main groups are numbered from 1 to 7 going from left to right, and the last group on the right is group 0.

Energy can be transferred from one place to another in many different forms. We'll also see what renewable and non-renewable sources are and how energy is generated from them.

Non-renewable

We get energy from many different types of energy resources, including fuels, food and stores of energy such as batteries or the wind. We can divide energy resources into two categories: non-renewable and renewable.

Renewable resources

Renewable energy resources can be replaced, and will not run out. Be careful - it is not true to say that they can be re-used.