Biology Revision Notes

When the body is cold 1. The small capillaries near the surface of the skin constrict (vasoconstriction) so less blood flows nearer to the surface, and less heat is lost through he blood. 2. The hair click here for full revision note

Sensory Neurone The nerve impulses travel from left to right in this diagram of a sensory neurone. A stimulus causes the impulse to be produced by a sense organ. (skin / ears / eyes / tongue / nose) click here for full revision note

Leaching describes the "washing out" from soils any soluble chemicals that are not "bound" to the soil particles. It occurs as excess rain (or flood) waters drain through the soil. click here for full revision note

The impact of human activities on the earth has become noticeable and significant during the last century resulting from: Increasing population - this resulted from increased food supply and improved click here for full revision note

Diffusion is the seemingly random movement of a substance from where these particles are in high concentration to where there are fewer. The diffusion stops where there is no concentration gradient ex click here for full revision note

DNA The molecule which contains genes. It's shaped like a double helix (a spiral) Chromosomes Found in the cell nucleus: X-shaped things made up of long coils of DNA click here for full revision note

Protoplasm Consists of cytoplasm and nucleus. Cytoplasm Jelly like substance where chemical reactions take place and other parts are embedded. Nucleus click here for full revision note

Living things are grouped into 1 of 5 kingdoms which are as follows: Animals, Plants, Fungi, Protista, and Monera. The list below shows the other attributes (in order) which are used to more accuratel click here for full revision note

Movement Animals move to find food and away from predators and plants move towards light. Reproduction Both animals and plants reproduce to keep their spec click here for full revision note

Between divisions, a copy of each chromosome is made. The chromosomes then start to become visible. The centrioles separate and move to opposite poles (ends) of the cell. The chromosomes are clearly v click here for full revision note