B2 - Cell Division

Question 0

What do the nuclei of body cells contain?

Answer 0

23 pairs of chromosomes

Question 1

What are body cells?

Answer 1

All of our cells other than our gametes (sex cells)

Question 2

What are chromosomes?

Answer 2

Strands of DNA that have been passed from the mother and father

Question 3

Why do chromosomes match up into pairs?

Answer 3

They have the same sets of genes

Question 4

What are genes?

Answer 4

Sections of chromosomes that carry instructions to make proteins

Question 5

What happens in mitosis?

Answer 5

The pairs of chromosomes double up (replicate)

The cell divides into 2 new daughter cells

Question 6

What are daughter cells?

Answer 6

The two cells that are identical to each other and to the original parent cell before the mitosis has taken place

Question 7

What are diploid cells?

Answer 7

Cells that have 23 pairs of chromosomes

Question 8

What is a zygote?

Answer 8

Fertilised egg

Question 9

What does meiosis produce?

Answer 9

Gametes (sex cells)

Question 10

How does meiosis work?

Answer 10

It doubles up the pairs of chromosomes
The cell divides into 2 identical cells with 23 pairs of chromosomes
The cells divide again to form 4 different cells with 23 single chromosomes each

Question 11

What are haploid cells?

Answer 11

Cells with 23 single chromosomes

Question 12

What type of cells is haploid

Answer 12

Gametes (sex cells)

All body cells are diploid

Question 13

What is a stem cell?

Answer 13

A cell that has the ability to become a different type of cell

Question 14

What are embryonic stem cells?

Answer 14

Cells in an embryo that can become any type of cell because they are unspecialised

Question 15

What are adult stem cells?

Answer 15

Unspecialised cells that can become multiple types of cell but not any type

Question 16

What is the main place in the body where adult stem cells be found?

Answer 16

Bone marrow

Question 17

How does asexual reproduction work?

Answer 17

Using mitosis

Question 18

What 2 things does mitosis do?

Answer 18

Replaces lost and damaged cells

Grows muscles and bones

Question 19

What is DNA and where is it found?

Answer 19

A type of acid that contains all of the instructions to put an organism together and make it work

In nucleus of cells in the chromosomes

Question 20

What is a gene?

Answer 20

A section of DNA that contains all of the instructions to make a specific protein

Question 21

Describe how cells make proteins

Answer 21

They string together 20 amino acids in a particular order to make a specific protein

Question 22

What else does DNA do?

Answer 22

Because it tells the cell which proteins to make, that means that it determines what type of cell it is

Question 23

In what 2 ways is DNA fingerprinting used?

Answer 23

Forensic science

Paternity testing

Question 24

What are the 3 main uses for stem cells?

Answer 24

Adult stem cells can be used to cure disease (people with blood diseases can be treated by bone marrow transplants which contains stem cells that can turn into new blood cells) Embryonic stem cells can be used to replace faulty cells in people because of how changeable embryonic stem cells are To find out more about how cells differentiate and how people develop

Question 25

What are the 2 arguments against stem cell research?

Answer 25

Embryos shouldn't be used for research because each one is a potential life Scientists should concentrate on trying to find other sources of stem cells so that people can be helped without using embryos

Question 26

What are the 2 arguments for stem cell research?

Answer 26

People think that curing patients that already exist is more important than the rights of embryos The embryos used in research were usually unwanted ones and would be destroyed anyway

Question 27

What controls if you are male or female?

Answer 27

If your 23rd pair of chromosome is XX you are female XY is male

Question 28

Why are the arrangements XX and XY?

Answer 28

All egg cells come from women so in meiosis, the XX chromosome of the woman is split into 2 X chromosomes meaning the egg is always X Men have XY so the sperm cell can either get an X chromosome or a Y chromosome at a 50% chance

Question 29

Describe the Punnett square

Answer 29

You make a table and put the alleles / chromosomes of person 1 as the rows and person 2 as the columns For each cell of the table, you put the row and column of that row to make a chromosome / allele Example: If the rows were X and Y (a man) and the columns were X and X, the table would go from left to right as XX, XX, XY, XY

Question 30

Describe the genetic diagram

Answer 30

You put the 2 original pairs of chromosomes / alleles at the top in circles You draw lines down from these to the 4 individual chromosomes / alleles You draw lines from the individual constituents to make all the possible combinations at the bottom