Chapter 1: Characteristics and classification of living organisms

In this chapter you will be introduced to the characteristics that are common to all living organisms and an effective way of remembering them. You will also be shown why it is necessary to classify organisms (there are 8.7 miltion species). You will learn about why biologists use the internationally agreed system to organise organisms into groups and the main features used to place animals and plants into the appropriate kingdoms and subgroups. Can you name many of the plants and animals you see around you? Do you know any of their scientific names or the groups they belong to?

Movement

An action by an organism or part of an organism causing a change of position or place

Respiration

describes the chemical reaction in cells that break down nutrient molecules and release energy for metabolism

Sensitivity

the ability to detected respond to change in the internal or external environment

Growth

a permanent increase in size and dry mass

Reproduction

the process that makes more of the same kind of organism

Excretion

the removal of waste products of metabolism and substances in excess of requirements

Nutrition

the taking in of materials for energy, growth and development

Species

a group of organisms that can reproduce to produce fertile offspring

Genus ｟𝑃𝑙𝑢𝑟𝑎𝑙: genera｠

a group of closely related species

Binomial system

an internationally agreed system in which the scientific name of an organism is made up of two parts showing the genus and species

Population

a group of organisms of the same species populating a given area

Dichotomous key

a step by step approach to identify unfamiliar organisms. Each key is made up of pairs of contrasting features

Evolution

the gradual change in a species over time

Autotrophic

produces their own food through photosynthesis (or chemical energy

Heterotrophic

organisms that cannot make their own food

Kingdom

a category of living organisms

Arthropods

the arthropods include crustacea, insects, myriapods and arachnids. They have jointed limbs, antennae, compound eyes, an exoskeleton and a cuticle.

Insects

insects have a segmented body with a exoskeleton, 3 pairs of jointed limbs, compound eyes and usually wings. the segments are grouped into head, thorax and abdomen.

Arachnids

arachnids have a body that is divided into 2 regions; a combined head and thorax known as the 𝐜𝐞𝐩𝐡𝐥𝐨𝐭𝐡𝐨𝐫𝐚𝐱; and the abdomen. they have 4 pairs of limbs on their cephalothorax.

they also have 2 pairs of 𝐩𝐞𝐝𝐢𝐩𝐚𝐥𝐩𝐬. one pair is used in reproduction; the other is used pierce their prey and paralyze it with a poison secreted by a 𝐠𝐥𝐚𝐧𝐝 at the base.

There are usually several pairs of 𝐬𝐢𝐦𝐩𝐥𝐞 𝐞𝐲𝐞𝐬.

Myriapods

myriapods have a head and a segmented body with pair of legs