UNIT 3 Organisms in their environment
LESSON 7 The causes of variation
Aims
To understand how inheritance and the environment are related to variation.
Learning Objectives
Pupils should Know/be able to:
7a - that some characteristics are inherited
7b - that although individuals are like their parents they are not identical to them
7c - that offspring from the same parent show considerable variation
7d - that some variations are inherited
7e - how environmental differences can result in variations in a species
7f - to interpret secondary data and draw conclusions from it
7g - to present ideas about causes of variation
HSW1.1a3 – focus on using scientific evidence to support or disprove a theory
POSSIBLE ACTIVITIES
Activity 1 Objectives 7a, 7b, 7c, 7d.
Spectrum Biology p40 provides information relating to variations between members of different
generations of a family. Ask students to identify patterns of similarities which suggest real or
fictional inherited features and ask them questions, eg What features are inherited in their own
families? Challenge them to consider why some members of the family share common features that
may not be shown by other members. Establish that this may be because inherited characteristics
were not passed on from parent to offspring or that there are other causes of variation (U3.7W1).
(W/S 7D.2a).
Activity 2 Objectives 7e, 7f, 7g.
Show pupils photographs or other secondary sources (Spectrum Biology p41) of information
illustrating variation related to environmental causes, + others e.g. trees grown in windy and nonwindy environments, gentian plants growing above and below the snowline, healthy and
undernourished children, and then ask pupils to review their work on variations within a species
and to consider the causes and origins of the variations.
Ask pupils to think about their own observations of animals and plants and to suggest ways in
which the environment might cause variations between individuals.
Present pupils with data, e.g. nettle leaf size in sunny and shaded positions, dog-whelk shell size on
sheltered and exposed shore, (U3.7W2 Exploring Science 7Db/6)and ask them to suggest why the
variations occurred.
Activity 3 Objectives
Risk Assessment.
Suggested Homework Tasks
U3.7W3 (Spectrum 7D.2b). Finding out if variations runs in families.
Resources: Lesson 7
Activity
Resources required
1
Spectrum Biology
U3.7W1
2
U3.7W2
HW
U3.7W3