91Èȱ¬

Cells are microscopic building blocks of unicellular and multicellular living organisms. Animal, plant, fungal and bacterial cells are different in terms of structure but also have many similarities.

All cells are enclosed by a cell membrane, which is selectively permeable. Molecules can move into or out of cells by diffusion and active transport. Cells can gain or lose water by osmosis.

DNA carries the genetic information in the cells of all living organisms. It contains codes for the assembly of amino acids into all the proteins required in the body.

Proteins consist of combinations of amino acids. Body proteins include structural proteins, enzymes, hormones and antibodies. The shape of an enzyme allows it to speed up a biological reaction.

Bacteria exchange DNA using plasmids; viruses invade cells by first inserting their genetic material. Genetic engineering is the transfer of DNA between organisms using biotechnology.

Most cell activity requires chemical energy. Respiration is the cellular process of releasing energy from food and storing it as ATP.

Cell division allows for growth and replacement of dead cells. Most multicellular organisms are made of different cell types that are specialised to carry out specific functions.

Communication between cells in a multicellular organism occurs by use of nerve impulses or hormones. The central nervous system produces electrical impulses for rapid response.

New organisms are produced when male and female haploid gametes fuse. In mammals, gametes are produced in the testes or ovaries of individuals but anthers and ovaries are on the same flowering plant.

The phenotype for a characteristic like eye colour is the result of the combination of alleles. If the alleles in the parental genotype are dominant or recessive, probable outcomes can be predicted.

Multicellular organisms require transport systems to supply their cells and remove waste products. Plants transport substances through xylem and phloem.

Multicellular organisms require transport systems to supply their cells and remove waste products. The heart uses blood vessels to transport these substances around the body.

Humans require transport systems to supply their cells and remove waste products. Gas exchange occurs in the lungs and food molecules are absorbed by the digestive system.

An ecosystem is a community of animals, plants, micro-organisms, non-living things and their shared environment. Find out about energy transfer, niches and competition in ecosystems.

Abiotic factors are non-living variables. Biotic factors are the interactions between organisms. Both affect diversity and distribution. Sampling helps us to estimate numbers of organisms in an area.

Photosynthesis is the process by which green plants use sunlight energy to make their own food. It takes place inside the chloroplasts of plant cells.

All organisms require energy. The feeding relationship in an ecosystem can be shown in a foodchain. Learn about pyramids of biomass, energy and numbers.

A growing human population demands increased food production. Farmers try to meet that demand by intensive farming, using fertilisers and pesticides that are impacting on the environment.

Mutations can alter the genes of individuals in a beneficial or detrimental way and introduce variety into a species.

There is a range of apparatus that National 5 Biology students must have knowledge of. The course also involves being able to describe and carry out experimental and measuring techniques.

Exam skills advice for National 5 Biology