Inheritance, Variation, Evolution-

Question 1

Define the term variation

Answer 1

Differences in the characteristics of individuals within a population

Question 2

State 3 causes of variation within a population

Answer 2

Genetics
Environment
Combination of genetics and the environment

Question 3

Explain how genetics can lead to variation in a population

Answer 3

Different individuals will inherit different combinations of alleles

The different combination of alleles will cause differences in the proteins that are or are not produced

This will cause differences in the characteristics in the different individuals

E.g. eye colour, blood group, genetic disorders such as cystic fibrosis

Question 4

Explain how the environment can lead to variation within a population

Answer 4

Different environmental factors can affect certain characteristics in individuals

e.g.

Road accident → loss of a limb

Question 5

Explain how genetics and the environment can lead to variation in a population

Answer 5

Individuals who possess certain genes and are exposed to certain environmental factors can have different characteristics

Question 6

State what factors influence most physical characteristics

Answer 6

Genetics AND the environment

Question 7

State what causes variation within a population

Answer 7

Mutations

Question 8

Define the term ‘evolution’ Hint: 3 key parts to this definition

Answer 8

A change in the inherited characteristics of a population over time

Through process of natural selection

Which results in formation of a new species

Question 9

Explain the theory of natural selection

Answer 9

A mutation occurs within an individual in a population

This causes variation to develop within population

Some individuals are more suited to their environment

Those more suited to environment are more successful

These individuals are more likely to survive and breed

These individuals then pass on the alleles for the beneficial characteristics to their offspring

Over time the beneficial alleles will become more common in the population
Over time the variants that posses the best phenotypes are selected for and increase in number

Question 10

Define the term ‘selective breeding’

Answer 10

Selective breeding is process by which humans breed plants and animals for particular genetic characteristics

Question 11

State the 4 key steps in artificial selection

Answer 11

• choose parents with the desired characteristic from a mixed population
• breed together

From offspring breed those with desired characteristic together

-continues over many generations until all the offspring show the desired characteristic

Question 12

Give 4 features that have been selected for in selective breeding

Answer 12

Disease resistance in food crops

Animals which produce more meat or milk

dogs with a gentle nature

Large or unusual flowers

Question 13

State 3 disadvantages of using selective breeding

Answer 13

Inbreeding can result in a reduced gene pool

Inbreeding can result in health problems

Inbreeding results in reduced variation within the population

Question 14

Explain what is meant by the expression ‘reduced gene pool’

Answer 14

The number of different alleles in a population decreases

Question 15

Explain how artificial selection can result in health problems in the population

Answer 15

Selective breeding can lead to ‘inbreeding’ where some breeds are particularly prone to disease or inherited defects

This is because of a reduced gene pool

Question 16

Explain how artificial selection can cause problems is a new disease occurs

Answer 16

• due to selective breeding there is less variation in a population
• So all individuals in the population have very similar characteristics
• so if one individual is likely to be killed by new disease , all individuals in population are also likely to die from the new disease

due to less chance of any resistant alleles being in a population

Question 17

Give 3 reasons why a gardener/farmer may use selective breeding

Answer 17

To produce a crop with higher yield

To produce a crop with more fruits

To produce a crop with larger fruits

Question 18

Describe the process of genetic engineering

Answer 18

A process which involves modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic

Question 19

Give 2 characteristics that have been genetically engineered in plants

Answer 19

Resistant to diseases

produce bigger better fruits

Question 20

Describe the 10 key steps in genetic engineering

Answer 20

useful gene is isolated from on organiskms genome using enzymes and is insereted into a vector

vector = bacterial plasmid or a virus

The cut plasmids and the desired gene are mixed together in the presence of DNA ligase

The DNA ligase joins the plasmid and desired gene together to form a recombinant (hybrid) plasmid

The recombinant/hybrid plasmid is inserted back into the bacteria

The bacteria are grown in large scale fermenters

The bacteria produce the required protein
The protein is extracted, purified and packaged for use

Question 21

Give 2 examples of genetic engineering

Answer 21

Production of human insulin (Humulin) to treat type I diabetics

Production of GM crops

Question 22

Give 4 reasons scientists may want to use genetic engineering in plants

Answer 22

To produce a herbicide or insecticide resistant crops

To produce plants with larger fruits

To produce plants which are disease resistant

To produce crops with greater yield

Question 23

Give 2 concerns some people have with GM crops

Answer 23

We do not yet know the long-term effect of consuming GM food i.e. they may have negative impacts on human health

Transplanted herbicide resistant genes may spread to other plants and lead a new ‘super weed’ variety

Question 24

Give 3 reasons why some people are in favour of GM crops

Answer 24

It can be used to produce food that is rich in certain nutrients

There are no studies to date that indicate ther are long-term side effects of consuming GM foods

GM crops increase the yield, making more food

It can help provide food security for a growing human population

Question 25

Give an example where a GM crop has been used to help reduced disease

Answer 25

The use of GM rice called ‘golden rice’

Which is rich in Vitamin A

To prevent a specific form of blindness In developing countries which have poor diet and rely heavily on rice

Question 26

State the two methods that can be used to clone plants

Answer 26

Tissue culture

Cuttings

Question 27

Define the term ‘tissue culture’

Answer 27

The process of using small groups of cells from part of a plant to grow identical new plants

Question 28

Give 2 uses of tissue culture

Answer 28

preserving rare plant species

producing large numbers of genetically identical plants commercially in nurseries

Question 29

Give 2 advantages of using tissue culture

Answer 29

• Only a few cells are needed

- The technique can be used throughout the year

Question 30

Give 2 disadvantages of using tissue culture

Answer 30

• The cloned plants will all be susceptible to the same diseases
• technique is slow

Question 31

Describe how tissue cultures are carried out

Answer 31

A few plant cells are selected from the plant with the desirable characteristics

The cells are placed in a growth medium which contains nutrients and growth hormones

The cells grow into plantlets
Which are genetically identical i.e. clones

Question 32

Define the term ‘clone’

Answer 32

Individuals which have the same genetic information (DNA)

so have the same characteristics

Question 33

Explain why gardeners may use cuttings

Answer 33

Simple method

can produce identical new plants from a singlee parent plant

Question 34

Give 2 advantages of using cuttings

Answer 34

simple procedure

cheap technique

Question 35

Give 2 disadvantages of using cuttings

Answer 35

• cloned plants will all be susceptible to the same diseases

- Only a limited number of cuttings can be taken

Question 36

State the 2 techniques that can be used to clone animals

Answer 36

Embryo transplants

Adult cell cloning

Question 37

Define the term ‘embryo transplants’

Answer 37

process which splits apart cells from a developing animal embryo before they become specialised, then transplanting the identical embryos into host mothers

Question 38

Describe the 7 main steps when carrying out embryo transplants

Answer 38

Sperm cells from a male with the desirable characteristics are collected

Ova from a female with the desirable characteristics are collected

The sperm are then used to fertilise the ova to form zygote

The zygote divides by mitosis and develops into an embryo

The embryo is then split into many smaller groups of cells (clones)

The clones are then implanted into the uterus of other females

The cloned embryos then develop into new individuals which are all genetically identical

Question 39

State the advantage of using embryo transplants

Answer 39

Hundreds of genetically identical offspring can be produced each year from one prize male and one prize female

Question 40

Describe the 5 main steps in adult cell cloning

Answer 40

The nucleus is removed from an unfertilised egg cell

The nucleus from adult body cell, such as a skin cell, is inserted into the egg cell

An electric shock stimulates the egg cell to divide to form an embryo

These embryo cells contain the same genetic information as the adult skin cell

When the embryo has developed into a ball of cells, it is inserted into the womb of an adult female to continue its development

Question 41

State 3 concerns some people have with the use of animal cloning techniques Applies to both adult cell cloning and embryo transplants

Answer 41

The production of clones reduces the gene pool

The variation within the population decreases

If a new disease occurs then the entire population may be wiped out (killed) as there is less chance of having an allele that provides resistance to the disease