Variation and Evolution

Question 1

Variation

Answer 1

Difference between members of the same species

Question 2

Sources of genetic variation

Answer 2

Mutation - Gene muations, Chromosome mutations

Sexual reproduction - Independent assortment, Random fertilisation

Question 3

Mutation

Answer 3

The change in DNA/Genotype in a cell

Question 4

Gene mutation + Example

Answer 4

Change in structure of a single cell

Example: sickle cell anaemia

Question 5

Chromosome mutation + Example

Answer 5

Change in structure or number of chromosomes

Example: Down’s Syndrome

Question 6

Mutagen + Cause

Answer 6

Anything that can alter or damage DNA

Example: UV radiation, Asbestos, Viruses

Question 7

Evolution

Answer 7

The slow change in inherited characteristics over a long period of time

Question 8

Theory of natural selection

Answer 8

The process by which particular traits become more common in a population due to the trait becoming advantageous to the species

• Organisms struggle to survive
• Vary and some are better able to survive
• Become better adapted
• Pass on inheritable traits

Question 9

Who proposed Theory of Natural Selection

Answer 9

Darwin and Wallace 1859

Question 10

How Darwin developed his theory

Answer 10

Observations:
Species overbreed
Limited supply of resources
Populations stay constant
Species show variations that are inherited
Conclusions:
-Organisms struggle to survive
-Vary and some are better able to survive
-Become better adapted
-Pass on inheritable traits

Question 11

Evidence for the theory of natural selection

Answer 11

Palaentology - study of fossils - increased complexity the nearer they are to the surface
Comparative anatomy
Comparative embryology

Question 12

Example of evolution - Change + Reason

Answer 12

The modern horse
Change: Molar teeth developed larger grinding surface
Reason: Grassland plants tougher than marshland plants

Question 13

Species + Example

Answer 13

A group of similar organisms that are capable of interbreeding to produce fertile offspring
Example: Dogs

Question 14

Speciation

Answer 14

Formation of a new species following many changes until the species cannot interbreed to produce fertile offspring of the original species

Question 15

Heredity

Answer 15

Passing on of traits from parent to offspring through genes

Question 16

Non nuclear DNA/Extra-nuclear DNA

Answer 16

DNA that is found in the mitochondria and chloroplasts rather than the nucleus