DNA is an example of a nucleic acid. The other type of nucleic acid found in organisms is RNA (ribonucleic acid).

Viruses, although not living organisms, also contain a nucleic acid - some have DNA whereas others have RNA. When a virus infects a cell, it injects its DNA or RNA into the cell, and the infected cell then uses it to make more copies of the virus proteins.

DNA is the molecule which provides instructions for how a cell is built and functions. In simple terms, the DNA molecule is a molecular code which determines which proteins are synthesised by the cell. The precise type of DNA that a cell contains determines which organism the cell belongs to; in other words, the DNA in the nucleus of a frog cell is different from the DNA in the nucleus of a human cell.

All living organisms contain DNA (deoxyribonucleic acid) in their cells. In Prokaryotes (bacteria), the DNA is a single loop located in the cytoplasm. In Eukaryotes, the DNA is packaged using proteins into multiple linear strands called chromosomes.

Nonetheless, we do consider movement one of the characteristics of life since all cells are able to move components around inside the cytoplasm, even if this is not immediately visible to the naked eye.

Some plants have the ability to move tissues or organs, such as the opening and closing of stomata, and Venus fly traps can rapidly close their traps. Both of these are reversible, and so considered movement. The way in which plants 'bend' towards the light, however, is in fact a growth response and irreversible, and so not considered movement.

Many animals have the ability to move in the sense of locomotion (moving the whole organism from one place to place), although of course plants and some animals such as corals are fixed in one place.

Respiration is the release of energy (usually I the firm of the molecule called ATP (Adenosine Triphosphate)) through the oxidation of an energy source (such as glucose).

Note that this kind of 'cellular' respiration is not respiration in the sense of breathing (taking air into the lungs), although the oxygen we breathe is used in cellular respiration. In prokaryotes like bacteria, respiration takes place in the cytoplasm but in eukaryotes respiration takes place in specialised organelles called mitochondria.

Aerobic respiration requires oxygen; anaerobic respiration can occur in the absence of oxygen and is carried out by some bacteria, some fungi and to a very limited extent by human muscles. This is similar to the process by which lactobacillus produces lactic acid used in the process of making yoghurt.

Sensitivity is the ability to respond to changes in their surroundings. In large multicellular organisms this is either through nervous systems or by using hormones (chemical messengers carried in the bloodstream). In plants, responses usually take the form of changes in the pattern of growth, and are regulated by chemicals.

In unicellular organisms, sensitivity is usually confined to moving in response to stimuli such as light or to chemicals.

Organisms can grow by either enlarging cells by increasing the volume of cytoplasm by cell division, which will increase the number of cells in the organism.

Multicellular organisms carry out both kinds of growth whereas when single-celled organisms divide the two individual daughter cells are considered different organisms.

Reproduction is a feature of all organisms. Most organisms reproduce sexually which leads to offspring that are variable. Some organisms may reproduce asexually, in which case the offspring are genetically identical to each other and to the parent offspring.

Excretion is the removal of waste products from an organism. The key part of this definition is that the substances excrete were produced by the organism. Examples include getting rid of carbon dioxide (a waste product from aerobic respiration), and urea (from the breakdown of excess proteins). Excretory products need to be removed from the cell or from the organism as they are often toxic at high concentrations.

Note that excretion is different from egestion. Egestion is the removal from the body of undigested food in the form of faeces. The cellulose cell walls of plants is a large component of faeces; humans are unable to digest cellulose and so this passes through the digestive system unchanged.

Nutrition is the obtaining of chemicals for either use in respiration to release energy or for use in the building of new molecules with which to construct new cells.

A cell or an organism may be described as carrying out heterotrophic or autotrophic nutrition. Heterotrophic organisms use pre-existing food molecules which they may digest and use. Animals are examples of heterotrophs. Autotrophic organisms synthesise food molecules from simpler molecules. All photosynthetic organisms are autotrophic - they use carbon dioxide and water to synthesise simple sugars such as glucose.

The most common nutrients you will encounter are glucose (a simple sugar) that is the main substance used in respiration and amino acids which are used to synthesise proteins.

Homeostasis is the maintenance of constant internal conditions despite changes in the external environment.

For complex multicellular organisms such as humans, this includes many factors such as keeping the concentration of blood (i.e. water balance), temperature, blood pH and the concentrations of mineral ions within strict limits

For unicellular organisms such as bacteria, they clearly have less of an ability to control factors such as temperature, but they still regulate the chemical composition of the cytoplasm such as pH, water levels and mineral ion concentrations.

Plants carry out respiration just like animals (and therefore use up oxygen) as well as carrying out photosynthesis (which produces oxygen)

Sometimes there may be a scale bar given instead - the actual length of the bar in the image (e.g. measured in millimeters) represents the stated length (usually in micrometers) of the real object.

Magnification is how many times larger a microscope makes an object look. The number of times an object has been magnified is often showed on or beside a picture so you can work out its actual size.

Works in combination with the eyepiece to magnify the image; there may be several to chose from on a rotating turret. The school microscopes have a 4x, 10x and 40x lens.

Tis is the one you look down; the school microscopes have a 10x one.

Where the specimen (slide) goes. There are usually clips of some description to hold it in place.

There are various types, but all vary the amount of light passing through the specimen. The diaphragm is just below the stage.

One for fine and one for coarse focus.; you should always focus with both hands to avoid straining the mechanism.

Light a bunson burner near where you are working to stop anything in the air landing on your bacteria.

Fungi feed by extracellular digestion. They secrete enzymes onto their food and absorb the smaller molecules that are released, such as glucose and amino acids

They are usually saprotrophic (digesting dead organisms or material) but some are parasitic and will ive in plants or animals

They grow a network or a mycelium of fine, branching, hair like structires called hypae, which can extend over many miles

Fungi periodical;ly send up fruiting bodies which produce reproductive spores

Some of these fruiting bodies are very large and are called 'mushrooms' or 'toadstools'

They reproduce asexually by budding, in which a small cell grows out of the side of an existing one

They can also reproduce sexually using a special reproductive cell called a shmoo

Shmoo's only have half the normal number of chromosomes and fuses with another shmoo of the opposite sex to form a zygote