Genes and variation

Question 1

What are the two types of variation in genes?

Answer 1

Environmental and genetic

Question 2

Give examples of a feature that is purely genetic

Answer 2

Eye colour
Blood group
Inherited disorders
Foot size

Question 3

How can your height be affected by both genetic and environmental impacts?

Answer 3

You are genetically so high, but whether you eat enough can impact your growth

Question 4

Where is the genetic material kept in a cell?

Answer 4

The nucleus

Question 5

Where are genes found?

Answer 5

Genes are in the chromosome and control the development of different characteristics

Question 6

What are alleles?

Answer 6

Different versions of the same gene (eg different eye colours)

Question 7

What is the difference between sexual and asexual reproduction?

Answer 7

Sexual - needs two parents and their gametes meet to create a baby

Asexual - only one parent is needed and they can clone themselves to have the exact same genes

Question 8

What are the disadvantages of asexual and sexual reproduction?

Answer 8

Sexual - genetic diseases can be passed on
Needs two parents

Asexual - if one disease can wipe out one, it can wipe out them all

Question 9

What are the advantages of asexual and sexual reproduction?

Answer 9

Sexual - species can evolve

Asexual - only needs one parent

Question 10

What is a gamete?

Answer 10

A sex cell with 23 chromosomes so when the two gametes come together they make 46

Question 11

What are mutations?

Answer 11

Changes to the genetic code

Question 12

How can the risk of mutations increase?

Answer 12

Nuclear radiation, x rays, ultraviolet light

Chemicals called mutagens (cigarette smoke has mutagens)

Question 13

What is cancer?

Answer 13

When mutated cells multiply rapidly in an uncontrollable way

Question 14

How can mutations be good?

Answer 14

They can benefit the organism, such as bacteria mutating to be resistant to antibiotics

This is natural selection

Question 15

What is shown in the gene Rr?

Answer 15

The dominant allele

The recessive is not shown

Question 16

What is homozygous and heterozygous?

Answer 16

Homozygous - two alleles are the same (CC or cc)

Heterozygous - two different alleles (Cc)

Question 17

How are genetic disorders caused?

Answer 17

By faulty alleles

Question 18

How is gene therapy treating CF?

Answer 18

Scientists can insert a healthy copy of the gene into the cells with the disease

Question 19

Why is cloning good for plant farming?

Answer 19

You can take cuttings of a plant and grow a clone cheaply and quickly, meaning you can grow your plants all year round

Question 20

Why and how have embryo transplants increased selective breeding?

Answer 20

Sperm cells are taken from the best bull and the female is given hormones to make lots of eggs, these eggs are then taken out

The sperm then fertilised the eggs artificially

When embryos form, they check the health of the embryo and keep the healthy ones, splitting them so they clone again so they have loads of clones of good cows

These are then implanted into surrogate mothers

Question 21

What are the advances and disadvantages of cloning?

Answer 21

Loads of animals can be cloned at once, all being great

There is no evolution or resistance, meaning if one gets a disease, all get the disease and all could die

Question 22

what is reproductive cloning?

Answer 22

When genetic material is taken from an adult cell to make a new organism that is a clone of that adult

An egg cell’s genetic material is removed and a complete set of chromosomes from the cell of the adult you’re cloning is inserted into the egg cell

Which grows into an embryo of the exact same cow

Question 23

What is therapeutic cloning?

Answer 23

Produce spare body parts for disease sufferers without them being rejected by the immune system

Question 24

How do carriers of a genetic disease happen?

Answer 24

If the disease is recessive, the carrier would be heterozygous so they carry the disease but don’t display it

If they have a child and they have two recessive alleles, the disease will be displayed

This means for a child to have it, their parents must either be a carrier or a sufferer

Question 25

How many chromosomes do you have in one cell?

Answer 25

46, so 23 chromatids

Question 26

What must the alleles be to display a recessive trait?

Answer 26

There must be two recessives (bb)

If there is a dominant alleles, it is expressed

Question 27

What are genes made up of?

Answer 27

They’re a strand of DNA