1 Gene technology involves altering the genes in an organism, which is then said to be genetically modifi ed.  2 The usual way of gene...

1 All living organisms may be classified into one of the five kingdoms: prokaryotes, protoctists, fungi, plants and animals. 2 Biodiversi...

1 Genetic variation within a population is the raw material on which natural selection can act.  2 Meiosis, random mating and the r...

1 Meiosis consists of two divisions. The first division, meiosis I , separates the homologous chromosomes, so that each cell now has only...

 1 Animals and plants have internal communication systems that allow information to pass between different parts of their bodies, and so ...

1 In photosynthesis, light energy is absorbed by chlorophyll pigments and converted to chemical energy, which is used to produce complex ...

1 Organisms must do work to stay alive. The energy input necessary for this work is either light, for photosynthesis, or the chemical po...

1 In an experiment investigating the effect of one variable on another, the independent variable is the one that you change and the depen...

1 A habitat is a place where an organism lives. The niche of an organism is the role that it plays in the community. 2 A population is ...

1 Phagocytes and lymphocytes are the cells of the immune system. 2 The diagram shows how to recognise phagocytes and lymphocytes in micr...

1 The term disease is defined as a disorder or illness that disrupts the normal functioning of the body or mind. Infectious diseases are ...

1 Tobacco smoke contains tar, carbon monoxide and  nicotine.  2 Tar settles on the epithelium lining the bronchi and  bronchioles an...

1 Multicellular organisms often have surfaces that are  specialised to allow exchange of gases to take place  between their bodies and t...

 1 The human heart, like that of all mammals, has two atria and two ventricles. Blood enters the heart by the atria and leaves from the v...

 1. Blood is carried away from the heart in arteries, passes through tissues in capillaries, and is returned to the heart in veins. Bloo...

1. Multicellular organisms with small surface area to volume ratios need transport systems. 2. Water and mineral salts are transported ...

1. DNA and RNA are polynucleotides, made up of long chains of nucleotides. 2. A nucleotide contains a pentose sugar, a phosphate group ...

1. Growth of a multicellular organism is a result of parent cells dividing to produce genetically identical daughter cells. 2. During c...

1 The basic structure of a membrane is a 7 nm thick phospholipid bilayer with protein molecules spanning the bilayer or within one or ot...

1  Enzymes are globular proteins which catalyse metabolic reactions. 2  Each enzyme has an active site with a specific shape, into which...