Unit 1

Key definitions

1. Movement is an action by an organism causing a change of position or place (see Chapter 14). 
2. Respiration describes the chemical reactions in cells that break down nutrient molecules and release energy (see Chapter 12). 
3. Sensitivity is the ability to detect and respond to changes in the environment (see Chapter 14).
4. Growth is a permanent increase in size (see Chapter 16). 
5. Reproduction is the processes that make more of the same kind of organism (see Chapter 16). Single-celled organisms and bacteria may simply keep dividing into two. Multicellular plants and animals may reproduce sexually or asexually. 
6. Excretion is the removal from organisms of toxic materials and substances in excess of requirements (see Chapter 13). 
7. Nutrition is the taking in of materials for energy, growth and development (see Chapters 6 and 7).

Key definitions 

1. A species is a group of organisms that can reproduce to produce fertile offspring. 
2. The binomial system is an internationally agreed system in which the scientific name of an organism is made up of two parts showing the genus and the species. The Latin form of the name allows it to be used in all the countries of the world irrespective of language barriers.
3. Archaea: containing ancient prokaryotic organisms which do not have a nucleus surrounded by a membrane. They have an independent evolutionary history to other bacteria and their biochemistry is very different to other forms of life.
4. Eubacteria: prokaryotic organisms which do not have a nucleus surrounded by a membrane.
5. Eukarya: organisms that have a membrane-bound nucleus. This domain is further subdivided into the kingdoms Protoctist, Fungus, Plant and Animal.