Unit 2 - Topic 13 - Variation and Selection Flashcards Preview

S2 GCSE Biology Unit 2 > Unit 2 - Topic 13 - Variation and Selection > Flashcards

Flashcards in Unit 2 - Topic 13 - Variation and Selection Deck (21)
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1
Q

Name two causes of variation.

A

Genetic factors

Environmental factors

2
Q

Name two types of variation.

A

Continuous variation

Discontinuous variation

3
Q

Name the factor(s) which affect continuous variation.

A

Genetic factors

Environmental factors

4
Q

Name the factor(s) which affect discontinuous variation.

A

Genetic factors

5
Q

What is continuous variation?

A

In continuous variation there is a gradual change in a characteristic across a population, which can be represented over a range of values.

6
Q

What is discontinuous variation?

A

In discontinuous variation the population can be clearly divided into discrete groups or categories.

7
Q

Why do identical twins often show small variations in their characteristics?

A

Environmental factors

8
Q

Give examples of continuous variation.

A

Height

Mass

9
Q

What graph can be used to display continuous variation?

A

Histogram

10
Q

What graph can be used to display discontinuous variation?

A

Bar chart

11
Q

Give examples of discontinuous variation.

A

Tongue rolling

ABO blood groups (A, B, AB, O)

12
Q

What is normal distribution?

A

Normal distribution is where most individuals are around the average or mean value and relatively few are found at either extremes.

Histogram.
Continuous variation.

13
Q

In continuous variation, the histogram produced will show …

A

Normal distribution

14
Q

Name the factors which affect height.

A

Height is continuous variation.

Genetic factors
Environmental factors

15
Q

What is natural selection?

A

Natural selection occurs when there is a competition for resources which creates a struggle for existence. The variation amongst the individuals in the population means that some individuals will be more adapted than others. (Variation is often caused by random genetic mutations).
Better adapted individuals survive this struggle for existence (survival of the fittest). They survive to breeding age and pass on their favourable genes to the next generation. Soon the desirable characteristics become more commonplace in the population.

16
Q

Who proposed the theory of evolution and natural selection?

A

Charles Darwin

17
Q

When was Charles Darwin born and when did he die?

A

1809

1882

18
Q

Give an example of natural selection in action.

A

Antibiotic resistance in bacteria.

19
Q

What is evolution?

A

Charles Darwin suggested that species have changed gradually through time (natural selection) in response to changes in the environment and that evolution is a continuing process.

20
Q

What is extinction?

A

Failure to adapt to changes in climate or the environment leads to extinction.

21
Q

What is a species?

A

Organisms which share similar characteristics and can breed together to produce fertile offspring.