If two objects are the same size, they have the same order of magnitude
1 order of magnitude = 10x
EXAMPLE: if a pineapple is 10x larger than a lemon, the pineapple is 1 order of magnitude larger than the lemon
2 orders of magnitude = 100x
EXAMPLE: If a dog is 100x the size of a woodlouse, the dog is 2 orders of magnitude larger than the woodlouse
Animal cells are eukaryotes as their genetic material is enclosed in a nucleus
Nucleus - encloses genetic material (DNA)
Cytoplasm - a watery solution where chemical reactions take place
Cell membrane - controls the molecules that can enter or leave the cell
Mitochondria - where aerobic respiration takes place
Ribosomes - sites of protein synthesis (also very small and can only be seen through an electron microscope)
Plant cells have a regular shape
Chloroplasts - contain chlorophyll and are the sites of photosynthesis
Cell wall - made from cellulose and strengthens the cell
Vacuole - helps give the plant cell its shape and is filled with a liquid called cell sap
Most animal cells are specialised, meaning they have adaptations to help carry out their function
When a cell becomes specialised, it is called differentiation
The job of a sperm cell is to join with an egg cell (ovum), in a process we call fertilisation
During fertilisation, the genetic information of the sperm cell and the egg cell combine, and the sperm cell has special adaptations to help this process
Sperm cells contain their genetic information in the nucleus. However, they have only half the genetic information of a normal adult cell
Sperm cells have a long tail which allows them to swim to the egg cell. The tail is streamlined to make this easier
Sperm cells have lots of mitochondria, which provides the energy needed for swimming
Sperm cells contain enzymes, which allow them to digest through the outer layer of the egg cell
The function of a nerve cell is to send electrical impulses around the body
The axon carries the electrical impulses from one part of the body to another
Myelin insulates the axon and speeds up the transmission of nerve impulses
On the end of the axon, there are synapses, which are junctions which allow the impulse to pass from one nerve cell to another
Dendrites increase the surface area so that other nerve cells can connect more easily
Muscle cells contain protein fibres which can change their length. When a muscle cell contracts their protein fibres shorten, which decrease the length of the cell
Muscle cells also have lots of mitochondria which provide energy for muscle contraction