Topic 6c- Evolution

Question 1

What is variation?

Answer 1

Differences between organisms of the same species

Question 2

What are the two types of variation?

Answer 2

Genetic and environmental variation

Question 3

What is genetic variation?

Answer 3

Since most animals get some genes from each parent, the new combination of genes results in genetic variation.

Question 4

Under what circumstance are two animals of the same species genetically identical?

Answer 4

Identical twins (remember identical because otherwise they cound be non-identical twins meaning they came from two seperate eggs instead of one)

Question 5

What is environmental variation?

Answer 5

When the environment in which an organism lives causes differences between members of the same species (e.g. a plant growing in the sun would grow luscious and green whereas one in the dark would grow tall and spindly with yellow leaves)

Question 6

What factors cause variation?

Answer 6

• Genetics
• Environment
• Mutations

Question 7

What are mutations?

Answer 7

Random changes in an organism’s DNA producing a genetic variant of the gene.

Question 8

What is the theory of evolution

Answer 8

All of today’s species have evolved from simple life forms that first started to develop over 3 billion years ago

Question 9

Describe the stages that result in a species evolving through the Darwin’s theory of evolution

Answer 9

1. All of the individuals within a species show a wide range of a particular characteristic
2. Because of this range of variation some of these individuals will be more suited to the environment than others
3. The individuals who are more suited to the environment will be more likely to survive and therefore more likely to breed successfully
4. The useful characteristic will be passed on to the offspring

Question 10

According to the theory of evolution, how long ago did life begin on earth?

Answer 10

3 billion years ago

Question 10

What is today’s theory of evolution by natural selection

Answer 10

1. Individuals within a species show wide range of variation in their characteristics (phenotypic variation) because of the mix of genetic variants present in the population.
2. Some genetic variants rise to characteristics that are better suited to the environment. Organisms with these characteristics have a better chance of survival and so are more likely to breed successfully.
3. So the genetic variants that are responsible for the useful characteristics are more likely to be passed on to the next generation.

Question 11

What is speciation?

Answer 11

When the phenotype of organisms change so much because of natural selection that a completely new species is formed.

Question 12

What is extinction?

Answer 12

When no living individuals of a species remain.

Question 13

Why might a species become extinct?

Answer 13

• The environment changes too quickly (e.g. destruction of habitiat)
• A new pretador kills them all
• A new disease kills them all
• They can’t compete with another (new) species for food
• Natural disaster- catastrophoc event happens that kills them all (e.g. volcanic erruption)

Question 14

What controvery did Darwin’s theory of evolution face?

Answer 14

• Went against common religious beliefs that God created everything on earth
• Darwin couldn’t explain why these new characteristics (mutations) appeared or how they were passed from individual organisms to their offspring
• There wasn’t enough evidence to convince other scientists at the time

Question 15

What was Lamarck’s theory of evolution?

Answer 15

Changes aquired in an organism over its lifetime would be inherited by its offspring