Variation And Evolution

Question 1

What is a mutation?

Answer 1

A change in the amount or structure of DNA

Question 2

What are mutagens?

Answer 2

Agents that cause mutations.

Question 3

What is a gene/point mutation?

Answer 3

Changes in a single gene.

Question 4

What are chromosome mutations?

Answer 4

Large changes in the structure or number of one or more chromosomes.

Question 5

What is evolution?

Answer 5

The way in which living things change genetically to produce new forms of life over long periods of time.

Question 6

What is natural selection?

Answer 6

The process by which those organisms with genetically controlled characteristics that allow them to be well adapted to their environments will survive and reproduce to pass on their genes to following generations.

Question 7

What is palaeontology?

Answer 7

Study of fossils.

Question 8

What causes inherited variations?

Answer 8

Sexual reproduction and by mutations.

Question 9

How does sexual reproduction cause genetic variation?

Answer 9

1. The way in which the chromosomes enter into gametes at meiosis
2. Crossing over, which happens during meiosis
3. The way in which sperm and eggs with many combinations of chromosomes may combine at fertilisation.

Question 10

What can a mutation cause?

Answer 10

1. New alleles
2. Beneficial phenotypes
3. No noticeable effect
4. Benign/malignant tumours
5. Genetic defects in offspring.

Question 11

State the observations of Darwin’s theory of natural selection and the conclusions.

Answer 11

Ob1- organisms overbreed
Ob2- population numbers tend to remain static
Con1- not all members of a pop can survive, so there’s a struggle for existence.
Ob3- inherited variations arise in a population
Con2- nature selects those organisms most suited to their environment.

Question 12

What can fossils form as?

Answer 12

1. Entire organisms
2. Preserved parts
3. Seeds
4. Pollen grains
5. Imprints.

Question 13

What does fossil evidence indicate?

Answer 13

1. Life has changed over time
2. Life has become more complex
3. The changes can be linked to environmental change.

Question 14

What does the evolution of the horse show?

Answer 14

That over 60 million yrs they have grown in size.

Question 15

What are the main categories of mutagens?

Answer 15

1. Ionizing radiation such as x-rays, gamma rays, cosmic rays and UV radiation
2. Chemicals such as formaldehyde, tobacco smoke and pesticides.

Question 16

Give an example of a gene mutation?

Answer 16

Sickle cell anaemia

Question 17

Give an example of a chromosome mutation

Answer 17

Down’s syndrome.

Question 18

Who are the 2 men responsible for the theory of natural selection?

Answer 18

Darwin and wallace