B2 - Cell Division

Question 1

What part of the cell contains chromosomes?

Answer 1

The nucleus

Question 2

What do chromosomes carry?

Answer 2

The genes

Question 3

What are genes

Answer 3

Sections of the DNA which contain the instructions for making new cells

Question 4

How many chromosomes do humans have?

Answer 4

46 chromosomes

Question 5

How many chromosomes does a haploid cell have?

Answer 5

23 chromosomes

Question 6

How many chromosomes does a diploid cell have?

Answer 6

46 chromosomes

Question 7

What are gametes, and give two examples.

Answer 7

Sex cells - egg cells and sperm cells

Question 8

What is the name of the series of stages cells undergo to divide?

Answer 8

The Cell Cycle

Question 9

What process is involved in the cell cycle?

Answer 9

Mitosis

Question 10

What is the product of mitosis?

Answer 10

Two identical cells

Question 11

What is asexual reproduction?

Answer 11

Reproduction with a single parent

Question 12

Why is there no genetic variation in asexual reproduction?

Answer 12

Genes of the cell is taken from a single parent therefore there will be no variation.

Question 13

At what time in your life is the cell cycle the shortest?

Answer 13

When a baby is developing in the womb.

Question 14

At what point is the cell cycle the longest?

Answer 14

Old age

Question 15

When does the cell cycle in a person begin to slow down?

Answer 15

After puberty

Question 16

What cells continue to divide (fairly) rapidly throughout your life?

Answer 16

Cells in the hair, the skin, the blood, and the lining of the digestive system

Question 17

Which stage is the longest stage in the cell cycle?

Answer 17

The first stage

Question 18

What happens in stage 1 of the cell cycle?

Answer 18

Cells grow bigger
Mass increases
Continue with normal cell activities

Replicates their DNA
Forms two copies of each chromosome
Ready for division

Increase the number of sub-cellular structures:
• Mitochondria
• Ribosomes
• Chloroplasts (plants)

Question 19

What happens in stage 2 of the cell cycle?

Answer 19

Mitosis
One set of chromosomes is pulled to each end of the dividing cell
Nucleus divides

Question 20

What happens in stage 3 of the cell cycle?

Answer 20

Cytoplasm and cell membranes divide to form two identical daughter cells

Question 21

About how many body cells die every minute?

Answer 21

300 million

Question 22

What is a stem cell?

Answer 22

An undifferentiated cell

Question 23

What happens to a cell to become differentiated?

Answer 23

Some of the genes are switched off, except those that will be used for its specific function

Question 24

What are two places stem cells can be taken from in humans?

Answer 24

Embryo

Adult bone marrow

Question 25

Where are stem cells found in plants?

Answer 25

Tips of the roots and shoots - meristems

Question 26

Why aren't nerve cells replaced when they are damaged?

Answer 26

They do not divide | They are not replaced by stem cells

Question 27

In a mature animal, what is cell division mostly for?

Answer 27

Repair and replacement of damaged cells

Question 28

How many times can a plant cell differentiate?

Answer 28

As many as they want

Question 29

How often does mitosis take place in the meristems?

Answer 29

Almost continuously

Question 30

How do plant cells grow?

Answer 30

They elongate

Question 31

Producing identical offspring is known as what?

Answer 31

Cloning

Question 32

How does cloning a plant work?

Answer 32

Under the right conditions, a plant cell will become unspecialised. These cells then undergo mitosis More undifferentiated cells are therefore made Under new conditions, the now-stem cell will differentiate into a different cell Necessary plant tissues such as: Xylem, phloem, photosynthetic cells, and root hair cells can be made. The new plant will be identical to the original

Question 33

Why is it difficult to clone animals?

Answer 33

Most stem cells differentiate early i embryo development. | They cannot be reverted.

Question 34

Egg and sperm cells fuse to form a?

Answer 34

Zygote

Question 35

The zygote divides and becomes what?

Answer 35

A hollow ball of cells called an embryo

Question 36

What are found in the inner cells of the embryo

Answer 36

Embryonic stem cells

Question 37

What do embryonic stem cells do?

Answer 37

Differentiate to form all the specialised cells in the body

Question 38

Why can spinal injuries cause paralysis?

Answer 38

Spinal nerves cannot repair themselves

Question 39

What breakthrough occurred in 1998?

Answer 39

Two scientists managed to culture human embryonic stem cells, capable of forming other cells

Question 40

What happened in 2010?

Answer 40

The first trials testing the safety of injecting nerve cells into the spinal cords of paralysed human patients were carried out.

Question 41

What happened in 2014?

Answer 41

Doctors transplanted embryonic stem cells into the eyes of people going blind as a result of macular degeneration It was a small study to check the safety of the technique.

Question 42

What happened as a result of the test in 2014?

Answer 42

The patients found that they could see better

Question 43

How can cloning be used to save rare plants from extinction?

Answer 43

They can produce a large number of one plant very quickly, economically, safely and reliably.

Question 44

Where may embryonic stem cells come from?

Answer 44

Aborted embryos | Spare embryos from fertility treatments

Question 45

What ethical issues surround the use of embryonic stem cells?

Answer 45

The embryo cannot give permission - this is a violation of human rights

Question 46

What is a religious reason against using embryonic stem cells?

Answer 46

Some religions cannot accept any interference with the process of human reproduction

Question 47

Describe the progress of developing the use of embryonic stem cells

Answer 47

Slow, expensive, difficult, hard to control

Question 48

What is a health issue with adult stem cells?

Answer 48

They may be infected with viruses - they can therefore be transferred between people

Question 49

What is another issue with the use of adult stem cells?

Answer 49

They may trigger an immune response.

Question 50

How must patients combat immune responses?

Answer 50

Immunosuppressant drugs which stop their body from rejecting new cells

Question 51

What are two other places that scientists have recently discovered to host embryonic stem cells?

Answer 51

Umbilical cord | Amniotic fluid

Question 52

What is therapeutic cloning?

Answer 52

Using cells from an adult to produce a cloned early embryo of themselves.

Question 53

What would therapeutic cloning provide?

Answer 53

A source of perfectly matched embryonic stem cells.

Question 54

What medical treatments could therapeutic cloning be used for?

Answer 54

Growing new organs for the original donor

Question 55

Why would the new organs not be rejected by the body?

Answer 55

They have been made by the body's own cells and have the same genes

Question 56

Where have scientists discovered stem cells in adults?

Answer 56

The tubes that connect the liver and the pancreas to the small intestine

Question 57

What have these stem cells been successfully turned into?

Answer 57

Special insulin-producing cells

Question 58

In the UK, stem cell research is being carried out into potential therapies to treat what?

Answer 58

``` Spinal cord after injuries Diabetes Heart after damage Eyesight Damaged bone and cartliage ```