B2.7 Cell division and inheritance

Question 1

How are chromosomes normally found in the body cells?

Answer 1

In pairs

Question 2

How do body cells divide?

Answer 2

By mitosis

Question 3

What do chromosomes contain?

Answer 3

Genetic information

Question 4

What happens when body cells divide by mitosis?

Answer 4

Copies of the genetic material are made then the cell divides once to form two genetically identical body cells

Question 5

When does mitosis occur?

Answer 5

In growth or to produce replacement cells

Question 6

How many chromosomes does a sex cell contain?

Answer 6

Only one

Question 7

What do cells in reproductive organs (testes and ovaries) divide to form?

Answer 7

Gametes

Question 8

What is the type of cell division in which a cell divides to from gametes?

Answer 8

Meiosis

Question 9

What happens when a cell divides to form gametes (meiosis)?

Answer 9

Copies of the genetic material are made then the cell divides twice to form four gametes, each with a single set of chromosomes

Question 10

What happens when gametes join at fertilisation?

Answer 10

A single body cell with new pairs of chromosomes is formed. A new individual then develops by this cell repeatedly dividing my mitosis

Question 11

When do animal cells differentiate?

Answer 11

At an early stage

Question 12

When do plant cells differentiate?

Answer 12

Throughout their life

Question 13

In animals what is cell division restricted to?

Answer 13

Repair and replacement

Question 14

Where are stem cells found?

Answer 14

Human embryos and adult bone marrow

Question 15

What can stem cells do?

Answer 15

Differentiate into many different types of cells, e.g. nerve cells

Question 16

What do human stem cells have the ability to do?

Answer 16

Develop into any kind of human cell

Question 17

What could treatment with stem cells be used to help?

Answer 17

Conditions such as paralysis

Question 18

What are the cells produced by asexual reproduction produced by?

Answer 18

Mitosis from the parent cells

Question 19

What do cells from asexual reproduction contain?

Answer 19

The same alleles as the parents

Question 20

Why does sexual reproduction give rise to variation?

Answer 20

Because when gametes fuse, one of each pair of alleles comes from each parent

Question 21

What are the sex chromosomes for females?

Answer 21

XX

Question 22

What are the sex chromosomes for males?

Answer 22

XY

Question 23

How many of the chromosomes in the human body cells contain the genes that determines the sex?

Answer 23

One

Question 24

Some characteristics are determined by…

Answer 24

A single gene

Question 25

What are the different forms of genes called?

Answer 25

Alleles

Question 26

What is a dominant allele?

Answer 26

An allele that controls the development of a characteristic when it is present on only one of the chromosomes

Question 27

What is the recessive allele?

Answer 27

An allele that controls the development of a characteristic only if the dominant allele is not present

Question 28

What are chromosomes made up of?

Answer 28

Large molecules of DNA which has a double helix structure

Question 29

What is a gene?

Answer 29

A small piece of DNA

Question 30

What does each gene code for?

Answer 30

A particular combination of amino acids which make a specific protein

Question 31

What does each person have?

Answer 31

Unique DNA (apart from twins)

Question 32

What can individual DNA be used to do?

Answer 32

Identify individuals in the process of DNA fingerprinting

Question 33

Some disorders are...

Answer 33

Inherited

Question 34

What is polydactyly?

Answer 34

Having extra fingers or toes

Question 35

What is polydactyly caused by>

Answer 35

A dominant allele of a gene and can therefore be passed on by only one parent who has the disorder

Question 36

What is cystic fibrosis?

Answer 36

A disorder of cell membranes

Question 37

Cystic fibrosis must be inherited from...

Answer 37

Both parents

Question 38

Can parents be carriers of the disorder without actually having it themselves?

Answer 38

Yes

Question 39

What is cystic fibrosis caused by?

Answer 39

A recessive allele of a gene and can therefore be passed on by parents, neither of whom have the disorder

Question 40

What can embryos be to test for these and other genetic disorders?

Answer 40

Screened