Revision Notes
Chemistry
Atoms are the smallest particle of a particular element.
Molecules are particles that contain 2 or more atoms joined together by chemical bonds.
Elements are substances that are made up of only one type of atom.
Compounds are substances form when two or more elements are joined chemically.
Metals are solid at room temperature, with the exception of mercury.
Metals are good conductors of electricity and heat.
Metals can usually be melted at high temperatures.
Non-metals cannot be polished to receive a shine, unlike metals.
Non-metals are brittle and shatter when hit.
Non-metals are poor conductors of electricity and heat.
Non-metals melt at low temperatures.
Metalloids are elements that have the properties of both metals and non-metals.
Metallic lustre is a shine emitted from smooth metallic surfaces.
Electrons are negatively charged particles that orbit the nucleus.
Protons are positively charged particles found in the nucleus that determine the atomic number of the element and the number of electrons can carry.
Neutrons are neutral particles with no charge that are found in the nucleus.
Plants
Xylem tubes can be up to 1 metre in length.
Xylems give support, strength and rigidity to the stem.
Water that enters the xylem in the roots is transported upwards through the stem to the leaves, which is a process also known as transpiration.
The phloem transport sugars to the whole of the plant.
Sugars are made in leaves of the plant during photosynthesis.
Sugars that are transported to other cells can be used as food to provide energy for the cell.
The process of breaking down sugars to create energy is called respiration.
Plants that live on land need to obtain their water and minerals through root systems.
There are two types of root systems in plants - the tap root system and fibrous root system.
Tap root systems penetrate deeply in the soil, while fibrous roots spread out widely to anchor the plant.
Water is taken in by plants