Inheritance

Question 1

When are the times when mitosis occurs?

Answer 1

1. When an organism is growing
2. When an organism is damaged the cells need to produce new cells

Question 2

What are the stages of meiosis?

Answer 2

1. Original cells chromosomes are copied forming 92 chromosomes or 46 pairs.
2. The cells divides into 2
3. They divide another time
4. Therefore the original has divided into 4 gametes.

Question 3

Where are gametes found?

Answer 3

Gametes are found in the reproductive organs.

Question 4

How are the chromosomes in the gametes?

Answer 4

The chromosomes are single and there are 23.

Question 5

What are the gametes’ differences from each other?

Answer 5

The gametes are all genetically different from each other

Question 6

What is the name of two gametes joining together?

Answer 6

Fertilisation

Question 7

What happens after fertilisation in the cell in terms of chromosomes?

Answer 7

The two gametes join and the 23 single chromosome join together forming 23 pairs of chromosomes

Question 8

Describe the link between the meiosis and fertilisation in terms of chromosomes

Answer 8

Whilst meiosis half’s the number of chromosomes in a cell, fertilisation the number of chromosomes is restored.

Question 9

Describe the link between the meiosis and fertilisation in terms of chromosomes

Answer 9

Whilst meiosis half’s the number of chromosomes in a cell, fertilisation the number of chromosomes is restored.

Question 10

Describe what happens in fertilisation in terms of meiosis and mitosis.

Answer 10

A Malé and a female gamete (eggs and sperms) join together to form a fertilised egg. Mitosis occurs and the cell copies and forms a clump of identical cells called an embryo. As the embryo develops ,through mitosis, the cells differentiate.

Question 11

What are advantages of sexual reproduction

Answer 11

Variation in offspring
If the environment changes variation gives survival advantages by natural selection
Natural selection can be speeded up by humans in selective breeding to increase food production e.g cows

Question 12

What are the advantages of asexual reproduction

Answer 12

Only one parents needed
Faster than sexual
More time and energy efficient coz no need for a mate
Many identical offspring when the conditions are preferable

Question 13

Which organisms produce both sexually and asexually?

Answer 13

1. Malaria parasites (asex in human host and sex in mosquito)
2. Many fungi (asexually in spores but sex to give variation)
3. Strawberry and Daffodil plants (sex for seeds and asex in runners for strawberry and asex as bulb division in daff)

Question 14

Where is dna found?

Answer 14

In chromosomes in the nucleus in the cell.

Question 15

What is dna?

Answer 15

A polymer made of molecules called nucleotides in two strands which make a double helix.

Question 16

What are the different nucleotides?

Answer 16

A - T
C - G

Question 17

What are the two bits in a nucleotide that never change?

Answer 17

Phosphate group and sugar molecule.

Question 18

What is the one part of a nucleotide that does change from molecule to molecule.

Answer 18

The base (ATCG)

Question 19

What form do nucleotides take?

Answer 19

Polymer as they line up with maybe even hundreds of them

Question 20

What are the nucleotides pairings and why?

Answer 20

A - T
G - C
Because the two strands in the double helix of dna are complimentary.

Question 21

What is a gene

Answer 21

Each gene codes for a particular sequence of amino acids to make a specific protein.

Question 22

What is the genome?

Answer 22

The entire genetic material of an organism.

Question 23

What is a stem cell

Answer 23

Cells that have not undergone differentiation.

Question 24

What is an undifferentiated cell

Answer 24

A cell which is not yet specialised

Question 25

What are the cells in early stages of developing of an embryo

Answer 25

Stem cells

Question 26

What is an embryonic stem cell

Answer 26

A stem cell found in the embryo which can differentiate into any kind of cell

Question 27

What is an adult stem cell

Answer 27

A stem cell that remains after embryonic stage and it can only differentiate into certain types of related cells

Question 28

Where are adult stem cells located

Answer 28

Brain eyes blood heart liver **bone marrow** skin and **muscle**

Question 29

What can bone marrow stem cells differentiate into

Answer 29

Blood cells and cells in the immune system

Question 30

What are the advantages and risks of medical treatment with stem cells

Answer 30

Can help with diabetes and paralysis Can transfer viral infections and ethical concerns

Question 31

Problems with embryo screening

Answer 31

Expensive Large number of embryos created but only small number is implanted so healthy ones are destroyed which can be unethical In future can use embryo screening to produce offspring with better feature which is also unethical

Question 32

Problems with embryo screening

Answer 32

Expensive Large number of embryos created but only small number is implanted so healthy ones are destroyed which can be unethical In future can use embryo screening to produce offspring with better feature which is also unethical

Question 33

What is embryo screeening

Answer 33

Embryos are tested to see if they have the alleles for inherited disorders, embryos which don’t have the defective alleles are implanted

Question 34

Gene therapy

Answer 34

In the future scientists may be able to correct faulty alleles which can treat inherited disorders however it is still experimental.

Question 35

What is cystic fibrosis

Answer 35

A disorder of cell membranes, controlled by a single gene, C - normal membrane function dominant, c - defective cell membranes recessive

Question 36

Polydactyl

Answer 36

Extra fingers and toes, caused by dominant alleles. Can’t be a carrier as when you have the dominant you will have the disorder.