Variation:
Variation - Differences in the species. The differences that occur both between different species and seperate species.
Species - A group of organisms with similar features that are capable of breeding. They are said to be fertile. Some are plants, some are animals.
There are two types of variation:
Discontinuous Variation (Bar Graph)
With discontinuous variation you either have a certain characteristic or you don't. This is inherited from your parents. An example would be eye colour or hair colour.

Continuous Variation (Line Graph):
With continuous variation you have a wide range of certain characteristics. We usually have to measure something. An example would be height.

Variation caused by the surroundings is called environmental variation. Examples of features that show environmental variation are your language and religion.
Variation in a characteristic that is a result of genetic inheritance from the parents is called inherited variation. Each egg cell and each sperm cell contains half of the genetic information needed for an individual. When these join at fertilisation a new cell is formed with all the genetic information needed for an individual.
Offspring - Any plant or animal formed by reproduction. Offspring are produced by their parents.
Artificial Selection:
Artificial selection is when people use selective breeding to produce new varieties of a species. A variety is a type of a particular species that is different in some clear way from other varieties of that species.
Suppose you wanted a variety of cow that produced a lot of milk. This is what you could do:
Choose or select the cows in your herd that produce the most milk
Let only these cows reproduce
Select the offspring that produce the most milk
Let only these offspring reproduce
Keep repeating the process of selection and breeding until you achieve your goal.
Natural Selection:
Within a population of animals, plants or any living organisms, there will be inherited variations. Within each species the individuals with the variations best suited to the environment will survive better than the others. More of them will survive to reproduce than the others. When they do, they pass on the genetic information for these variations to their offspring.
Species gradually evolve in this way. This process is called natural selection.
Over time a population can change so much it may even become a new species, unable to reproduce successfully with individuals of the original species.
Classification:
Classification - Organising living things into groups: Anatomy, Genetics.
Classifying organisms helps others understand which species you are talking about, it can group species based on shared characteristics
The first big division of living things in the classification system is to put them into one of five kingdoms. These are based on what an organism's cells are like.
Protists (EG: Amoeba)
Prokaryotes (EG: Bacteria)
Fungi
Plants
Animals
Respiration:
Respiration releases energy for cells from glucose.
This can be aerobic respiration, which needs oxygen, or anaerobic respiration, which does not.
During exercise, the breathing rate and heart rate increase. During hard exercise an oxygen debt may build up.
What is aerobic respiration?
Respiration is a series of reactions in which energy is released from glucose. Aerobic respiration is the form of respiration which uses oxygen. It can be summarised by this equation: glucose + oxygen → carbon dioxide + water (+ energy)
Energy is