B1.7 Genetic Variation

Question 1

What are chromosomes and where are they found?

Answer 1

Chromosomes are found in the cell nucleus and contain genes

Question 2

What is a gene?

Answer 2

A gene is a section of DNA coding for a particular protein

Question 3

How many chromosomes do humans have?

Answer 3

46 containing around 30,000 genes

Question 4

What are examples of inherited variation in humans?

Answer 4

Eye colour
Hair colour
Skin colour

Question 5

How can the environment cause variation?

Answer 5

Climate
Diet
Culture
Lifestyle
Language
Religion
Flower colour

Question 6

What factor determines body mass?

Answer 6

Both environmental and inherited factors

Question 7

What are gametes?

Answer 7

Sex cells
Female = eggs / ova
Male = sperm

Question 8

What is sexual reproduction?

Answer 8

When male and female sexual gametes fuse, this is called FERTILISATION

Question 9

How does sexual reproduction lead to genetic variation?

Answer 9

Some of the genetic from each parent mixes causing the offspring to not be identical to either

Question 10

How many chromosomes are in a gamete?

Answer 10

23

Question 11

How is asexual reproduction different to sexual reproduction

Answer 11

Only one parent is used

The offspring are genetically identical not varied

Question 12

What is an example of asexual reproduction in plants?

Answer 12

Underground food storage organs later develop into plants themselves
eg potatos and daffodils

Some plants produce runners with plantlets on them
eg strawberrys

Some plants produce side branches with plantlets
eg Busy lizzy

Question 13

What are examples of asexual reproduction in animals

Answer 13

Although it is rare, some animals do asexually reproduce
eg
sea anenomes
starfish

Question 14

What are the commercial benefits of plant cloning?

Answer 14

A plant can be produced efficiently and cheaply on a massive scale

Question 15

How can a plant be artificially cloned?

Answer 15

• Cuttings

- Tissue cultures

Question 16

How can plants be cloned with cuttings?

Answer 16

A branch of the plant is cut off and replanted using plant hormones to stimulate root growth
The cutting is usually covered in a plastic bag to ensure optimum warmth and moisture for the first few weeks

It is easy and accessible for gardeners to use

Question 17

How can plants be clones with tissue cultures?

Answer 17

A tissue sample of the plant is taken and placed in agar jelly with nutrients and auxins
The samples develop into tiny plantlets that can then be transferred into composts

The equipment is very expenisve and more difficult to achieve effective results than cuttings

Question 18

Why would people want to clone animals?

Answer 18

Animals with the most desirable features such as producing the largest yield of milk or meat can be reproduced

Question 19

How are animals artificially cloned through embryo transplants?

Answer 19

• A developing embryo is removed from the mother early on before the cells become specialised
• The cells are separated and grown in a lab
• They are transplanted into surrogate mothers
• Multiple, genetically identical, offspring are born

Question 20

How are animals artificially cloned through adult cell cloning?

Answer 20

• The nucleus is removed and discarded from an unfertilised egg
• The nucleus from an adult body cell is implanted into the egg cell
• The cell is given an electric shock to begin its division
• The ball of cells is implanted into a surrogate mother where it can continue to grow and develop

Question 21

How is genetic modification different from cloning?

Answer 21

• Produces a unique set of genes not an exact copy

- Genes can be swapped can transferred accros species

Question 22

How does genetic modification work?

Answer 22

Enzymes are used to remove sections of DNA and join them to a different string of DNA
This can cause the organism to have beneficial characteristics

Question 23

How can genetic modification be used in crops?

Answer 23

To create resistance against herbicides or pesticides

Question 24

How can insulin be mass produced using genetic modification?

Answer 24

The section of DNA coding for insulin production in the body is removed and inserted into a bacteria plasmoid
The Insulin can be grown quickly

Question 25

What are the advantages of genetic modification and cloning?

Answer 25

Can produce ideal plants and animals
Increase in production yield, less costly
Feeding growing / starving population with efficient yield

Question 26

What are the disadvantages of genetic modification and cloning?

Answer 26

Can reproduce plants or animals with genetic diseases
Is unethical
Unknown effect on plants, wildflowers, human health