✅ 1.2 Cell Division

Question 1

What does the nucleus of a cell contain?

Answer 1

The nucleus of a cell contains chromosomes

Question 2

What are chromosomes made up of?

Answer 2

Chromosomes are made up of DNA molecules

Question 3

What do chromosomes carry?

Answer 3

Chromosomes carry a large number of genes

Question 4

Explain the function of genes

Answer 4

Genes contain the instructions for making proteins

Question 5

How are chromosomes normally found?

Answer 5

Chromosomes are normally found in pairs of 23 per body cell, so 46 in total

Question 6

Name the process in which cells divide

Answer 6

Cell Cycle

Question 7

What is the cell cycle?

Answer 7

The cell cycle is a series of stages in which a cell divides

Question 8

Explain the 1st stage of the cell cycle

Answer 8

The 1st stage of the cell cycle is cell growth

1. The number of sub-cellular structures, such as the mitochondria and ribosomes increase
2. The cell itself grows in size
3. The DNA replicates to form 2 copies of each other

Question 9

Explain the 2nd stage of the cell cycle

Answer 9

Mitosis is when one set of chromosome is pulled to each end of the cell, and the nucleus divides into two

Question 10

Explain the 3rd stage of the cell cycle

Answer 10

The 3rd stage of the cell cycle is Cell Divison where:

• The cytoplasm and cell membrane divide to form 2 identical daughter cells

Question 11

What happens during mitosis?

Answer 11

During mitosis, the

Question 12

Give 3 functions of mitosis

Answer 12

Functions of mitosis:

• Growth and development of multicellular organisms
• Healing and repairing of organisms
• Mitosis occurs during asexual reproduction

Question 13

What are stem cells?

Answer 13

Stem cells are undifferentiated cells that have not yet become specialised, and can create more stem cells, from which they can differentiate to form other types of cells

Question 14

What is special about stem cells inside an embryo (embryonic stem cells)?

Answer 14

Stem cells inside the embryo are unspecialised so they can differentiate to produce a wide range of cells

Question 15

Embryo

Answer 15

An embryo develops from a fertilised egg

Question 16

What is the function of stem cells inside an embryo

Answer 16

Stem cells inside the embryo is to differentiate to produce many different cell types

Question 17

What is the nature of stem cells in adult animals

Answer 17

They can only differentitate into a limited range of cell types

Question 18

What is the function of stem cells in adult animals

Answer 18

To replace cells that are worn out or damaged

Question 19

Where can adult stem cells be found

Answer 19

Adult stem cells can be found in bone marrow

Question 20

What is special about adult bone marrow?

Answer 20

Stem cells from adult bone marrow can form many types of cells, including blood cells

Question 21

What conditions can stem cells be used to treat?

Answer 21

Treatment with stem cells can be used to help conditions such as diabetes and paralysis

Question 22

What are meristems?

Answer 22

Meristems are specialised tissues that produce plant stem cells

Question 23

What is special about plant stem cells?

Answer 23

Plant stem cells can differentiate into any type of plant cell throughout the life of the plant

Question 24

What is therapeutic cloning?

Answer 24

therapeutic cloning is a process that produces an embryo with the same genes as the patient, so that it can be used for medical treatment and will not be rejected by the patient’s body

Question 25

Explain the process of therapeutic cloning

Answer 25

1. The nucleus of a donated egg cell is removed and replaced with the nucleus of a patient’s cell
2. The egg cell develops into an embryo that has the same genes as the patient
3. The stem cells from the embryo are removed to treat the patient

Question 26

Why are stem cells not rejected by the patient’s body in therapeutic cloning?

Answer 26

They have the same genes as the patient’s body

Question 27

List 2 benefits of therapeutic cloning

Answer 27

• Stem cells can help treat many conditions such as diabities and paralysis
• The cells produced can be used for research

Question 28

List 3 issues of therapeutic cloning

Answer 28

• Ethical objections - Should an embryo be treated as a person?
• Stem cells have potential to transfer viral infections
• There is a risk of stem cells mutating and behaving like cancer cells

Question 29

List 3 benefits of using stem cells from meristems

Answer 29

• Plants can be cloned quickly and economically
• Rare species of plants can be cloned to protect from extinction
• Plants with useful features (like disease resistance) can be cloned to produce large numbers for farmers