Variation,Natural Selection and Selective Breeding

Question 1

What is variation ?

Answer 1

It is the differences between individuals

Question 2

What are the two main types of variation ?

Answer 2

• Continuous - e.g. Height, where there is a smooth range of measurements
• Discontinuous - e.g. Blood group, where there are distinct categories with no values in between

Question 3

Why are there differences between individuals ?

Answer 3

• differences in genes they inherit

* and the conditions in which they develop ( environmental causes )

Question 4

What happens when a mutation occurs in a body cell ?

Answer 4

It will affect only those cells produced by mitosis from the affected cell. This type of mutation is not inherited. Mutations in body cells can give rise to cancer of the cells that are affected.

Question 5

What happens when a mutation occurs during meiosis in a gamete ?

Answer 5

It will affect all the cells in the individual which develops from the gamete. This means that the mutation is inherited.

Question 6

What was Darwin’s theory based on ?

Answer 6

• all living things show variation

* all living things tend to over reproduce

Question 7

What was Darwin’s theory ?

Answer 7

• there will be a struggle for existence because organisms over reproduce, resources will be limited
• Some will be better adapted to their environment than others because they vary
• those who are best adapted to survive reproduce in great numbers, the less well adapted do not reproduce as much

Question 8

What is the anagram to help remember natural selection ?

Answer 8

M - MUTATION in individual
V - result in natural VARIATION
A - individual has an ADVANTAGE over others, extinction of species unable to compete
R - surviving individuals REPRODUCE
P - advantage alleles for mutation are PASSED on
S - repeated over SEVERAL generations

Question 9

What are Antibiotics?

Answer 9

There are chemicals that kill bacteria and do not harm animal cells

Question 10

How do you antibiotics not harm animal cells while killing bacteria ?

Answer 10

They target cell structures such as cell walls, which animal cells do not have

Question 11

How have antibiotics stoped working overtime ?

Answer 11

• originally, none of the bacteria was resistant to the antibiotic
• doctors began to use the Antibiotic, which kills the bacteria
• A chance mutation gave some bacteria resistance to the antibiotic
• these bacteria are better adapted to an environment in which the antibiotic was used
• they survive in greater numbers to reproduce and pass on the resistance allele
• this was repeated with each generation of bacteria
• The proportion of bacteria with resistant allele increased until most had the allele

Question 12

What does selective breeding mean ?

Answer 12

A means of producing animals and plants with desirable characteristics by choosing individuals to breed from and by repeating the process for many generations

Question 13

How is selective breeding performed ?

Answer 13

• selecting the desired organisms from the population and breeding them together
• look at the offspring for those with the best combination of desired features
• use only these individuals for breeding the next generation
• repeat the selection generation after generation

Question 14

Techniques for selective breeding

Answer 14

• traditional selective breeding
• artificial insemination
• embryo transplantation
• cloning
• genetic engineering