variation and evelution

Question 1

what is variation

Answer 1

Variation is the differences between individuals of the same species.

Question 2

what are the two things that affect variation

Answer 2

environmental
genetics

Question 3

what are the 2 types of variation

Answer 3

continuous and discontinuous

Question 4

continuous

Answer 4

controlled by many genes and the environment there is a continuous range of possibilities with no categories

Question 5

discontinuous

Answer 5

controlled by a single gene there are distinct groups

Question 6

Explain how sexual reproduction results in the variation seen in the plants in box Y

Answer 6

genes of gametes is not identical
They inherit different {genes} from both parents

Question 7

what is a mutation

Answer 7

a change in the sequence of DNA

Question 8

what affects the rate of mutation

Answer 8

Mutations are random and there is a greater chance of mutation if you are exposed to ionising radiation. The greater the exposure to ionising radiation the greater the chance of mutation.

Question 9

what is the cause of cystic fibrosis

Answer 9

a mutation in a single gene

Question 10

what does cystic fibrosis cause

Answer 10

cystic fibrosis causes a thick mucus to build up in the lungs, leading to the blocking of the bronchioles. It is caused by a mutation.

Question 11

what is the allele for cystic fibrosis

Answer 11

n

Question 12

natural selection
rules (VISITED)

Answer 12

Natural selection states that:

There is variation within a species due to difference in genes. This is called heritable variation.
Individuals with features that make them better adapted to the environment will survive and breed. This is ‘survival of the fittest’.
Genes are passed to offspring. This means that offspring inherit the features that make them better adapted to the environment.
As a result of this, over many years, a species may evolve and change.

Question 13

what causes extinction

Answer 13

Sometimes natural selection occurs too slowly for organisms to adapt to new environmental conditions. This means that organisms may become extinct.

Question 14

who introduced the theories of natural selection

Answer 14

Charles Darwin
Alfred Russel Wallace

Question 15

why are models of natural selection limiting

Answer 15

The prey animals do not move.
In reality, the background environment is usually more than one colour.
In reality, the number of offspring is not always the same.

Question 16

what is environmental variation

Answer 16

is caused by the environment in which the organism has developed in (eg) scars tattoos piercings this cannot be passed onto the next generation

Question 17

what is heritable variation

Answer 17

caused by differences in genesso thsi can be passes on fro m parent to child (eg) hair colour eye colour shape of nose

Question 18

what feature are a combination of both heritable and environmental variation

Answer 18

height and weight
if some body had the genetics to be tall but didn’t have the right diet when they ere younger then they may not reachtheir potential height

Question 19

how can a mutation be passed on

Answer 19

it will be passed on if there was a mutation in the sex cells but not if there was a mutation in the body cells

Question 20

what is sexual reproduction

Answer 20

Sexual reproduction is when the nuclei of the male and female gametes join together. This process is called fertilisation.

Question 21

hat does fertilisation produce

Answer 21

Fertilisation produces variation in the offspring. This means that offspring that are genetically different from the parents.

Question 22

asexual reproduction

Answer 22

Asexual reproduction produces offspring from one single parent. There are no gametes involved.

The offspring produced are genetically identical to the parent. The offspring are called clones.

Question 23

what is the advantage for farmer if their palnts have rproduced asexually

Answer 23

they will have the same cloned nice juicy fruits but the problems is that they can all die from the same disease

Question 24

what is gene therepy

Answer 24

Gene therapy involves inserting copies of a normal allele into the DNA of a person who carries the faulty cystic fibrosis allele.

Question 25

Problems that are linked to gene therapy include:

Answer 25

Problems that are linked to gene therapy include:

The alleles may join with DNA in incorrect places.
The alleles may not enter every target cell.
Treated cells (with the normal allele) will eventually be worn away and replaced by the patient’s own untreated cells (with the faulty allele). Gene therapy is therefore not a long-term solution as the normal alleles have to be continually reintroduced.

Question 26

how is the normal alle introduced in the lungs

Answer 26

The genes are introduced into the lung tissue using an inhaler.

Question 27

natural selction

Answer 27

process where organisms that are better adapted to an environment will survive and reproduce.