B1 6 Variation, Reproduction and New Technology

Question 1

Where are genes found?

Answer 1

Inside chromosomes made up of DNA, inside the nucleus of gametes.

Question 2

What are gametes?

Answer 2

Sex cells

Question 3

How many chromosomes do humans have in total?

Answer 3

46

Question 4

What do chromosomes always come in?

Answer 4

Pairs

Question 5

How many pairs of chromosomes do we have in our body?

Answer 5

23 pairs

Question 6

What is a gene’s job?

Answer 6

It controls the characteristics of an organism.

Question 7

How do genes do their job?

Answer 7

By controlling all the different enzymes and proteins made in the body.

Question 8

Why do chromosomes come in pair - what do they represent?

Answer 8

One from mother other from father

Question 9

What do each type gene control?

Answer 9

Different characteristics

Question 10

How do you inherit characteristics from parents?

Answer 10

Genes are passed on and carried by gametes.

Question 11

What are the two types of reproduction?

Answer 11

Asexual and sexual

Question 12

What is asexual reproduction?

Answer 12

It only involves one parent and therefore there is no joining of gametes and no genetic variety in the offspring. One cell of 23 pairs of chromosomes split into two sets of 23 pairs to make 46 chromosomes in total. The DNA replicates itself in each cell to form new cells which are genetically identical.

Question 13

What happens in sexual reproduction?

Answer 13

A gamete from each parent (female and male) joins together to form the offspring. Half the chromosomes contribute towards forming the offspring which means there’s genetic variety.

Question 14

What are the genetically identical offsprings of asexual reproduction known as?

Answer 14

Clones

Question 15

What is meant by the term variation?

Answer 15

Differences within a species

Question 16

What are the two types of variation?

Answer 16

Genetic and environmental

Question 17

What is meant by genetic variation? Give an example.

Answer 17

When an organism’s characteristics are determined by the genes inherited from their parents.

Eye colour

Question 18

What are genes?

Answer 18

The codes inside your cells that control how you’re made.

Question 19

What is meant by environmental variation? Give an example.

Answer 19

The environment that organisms live and grow in also causes differences between members of the same species.

Scars caused by accidents

Question 20

Put these statements in order:

• Inside each cell is a nucleus
• These chromososmes are made from a helix structure called DNA
• The DNA contains pairs of genes
• Your body is made of different cells
• Inside the nucleus are 23 pairs of chromosomes (46 in total)
• The genes control what an organism is like

Answer 20

1. Your body is made of different cells
2. Inside each cell is a nucleus
3. Inside the nucleus are 23 pairs of chromosomes (46 in total)
4. These chromososmes are made from a helix structure called DNA
5. The DNA contains pairs of genes
6. The genes control what an organism is like

Question 21

Put the following statements into order:

• Each gamete contains 23 single chromosomes
• Two gametes fuse together to form a zygote
• Sperm cells (from the father) and egg cells (from the mother) are called gametes.
• This means that the growing embryo is different from both its parents.
• In the zygote the 23 chromosomes join to form 23 pairs of chromosomes (46 in total)
• The zygote multiplies to form an embryo, it has half its genetic information from the father and half from the mother.

Answer 21

1. Sperm cells (from the father) and egg cells (from the mother) are called gametes.
2. Each gamete contains 23 single chromosomes
3. Two gametes fuse together to form a zygote
4. In the zygote the 23 chromosomes join to form 23 pairs of chromosomes (46 in total)
5. The zygote multiplies to form an embryo, it has half its genetic information from the father and half from the mother.
6. This means that the growing embryo is different from both its parents.

Question 22

Tick whether the statement refers to asexual or sexual:

Answer 22

Question 23

State an advantage and disadvantage of sexual reproduction?

Answer 23

Advantage: faulty material is not always passed on

Disadvantage: it is risky as it relies on two individual sex cells

Question 24

State an advantage and disadvantage of asexual reproduction?

Answer 24

Advantage: energy and time used by the organism when looking for a mate is less

Disadvantage: faulty material is definitely passed on

Question 25

How can scientists test variety?

Answer 25

Using identical twins brought up by different families.

Question 26

What are the methods involved in cloning through cuttings?

Answer 26

First you take a cutting by removing a small piece of the plant. You only need to take part of the stem or just part of a leaf. By using hormone rooting powder then keeping the plant under the right conditions you can create **several **genetically identical plants.

Question 27

State an advantage and disadvantage of using cuttings?

Answer 27

**Advantage**: it's cheaper **Disadvantage**: you can only produce a few plants at the same time

Question 28

What are the methods involved in tissue culture when cloning?

Answer 28

We take a few cells from the plant you want to clone, we then place them in a petri dish and stimulate them with plant hormones. We can create thousands of identical plants from just a few cells unlike cuttings.

Question 29

State an advantage and disadvantage of tissue culture?

Answer 29

**Advantage**: you can produce thousands of plants from a few plants rather than several **Disadvantage**: it's very expensive

Question 30

Why would people want clones of plants?

Answer 30

As they want plants with new characteristics and uses.

Question 31

Describe how embryos are cloned through embryo transplant?

Answer 31

1. Sperm cells are taken from the male and egg cells are taken from the female with the desired characteristics. 2. The sperm are then used to artificially fertilise an egg cell 3. The embryo that develops is then split may times (to form clones) before any cells 4. These cloned embryos can then be implanted into lots of host females (surrogates) 5. The babies that are born are genetically identical to each other.

Question 32

State an advantage and disadvantage of embryo transplant.

Answer 32

* *Advantage**: Organisms that are difficult or slow to breed normally can be reproduced quickly. * *Disadvantage**: All clones maybe wiped out if a disease comes across

Question 33

Put these statements in order for adult cell cloning: * Take an egg from the ovary of a second animal * Give the egg a small electric shock to start its dividing * The surrogate gives birth to a clone of the first as it has the same DNA * Take a small number of cells from an animal (the animal you want to clone) * Implant the dividing embryo into the uterus of a surrogate animal * Remove the DNA from the nucleus of the egg from the second animal * Extract the DNA from the nucleus of the cells extracted from the first animal * Insert the DNA from the first animal into the nucleus of the egg taken from the second.

Answer 33

1. Take a small number of cells from an animal (the animal you want to clone) 2. Take an egg from the ovary of a second animal 3. Extract the DNA from the nucleus of the cells extracted from the first animal 4. Remove the DNA from the nucleus of the egg from the second animal 5. Insert the DNA from the first animal into the nucleus of the egg taken from the second. 6. Give the egg a small electric shock to start its dividing 7. Implant the dividing embryo into the uterus of a surrogate animal 8. The surrogate gives birth to a clone of the first as it has the same DNA

Question 34

State an advantage and disadvantage of adult cell cloning.

Answer 34

**Advantage**: can produce medically useful animals **Disadvantage**: reduces variety so more likely to get wiped out

Question 35

What are the methods involved in genetic engineering?

Answer 35

(use image for method)

Question 36

What are the advantages and disadvantages of genetic engineering?

Answer 36

**Advantages**: can improve growth rates of animals and plants can improve food value of crops as genetically modified crops can be engineered to produce plants to make own pesticide or be resistant to herbicide used to kill weeds **Disadvantages**: insects may become herbicide resistant farmers in poor countries need to buy seeds every year