Cell division and inheritance

Question 1

In body cells, chromosomes are normally found in…

Answer 1

…pairs.

Question 2

Body cells divide by what process?

Answer 2

Mitosis.

Question 3

What happens when a body cell divides by mitosis?

Answer 3

Copies of the genetic material are made.

Then the cell divides to form two genetically identical body cells.

Question 4

Mitosis occurs why?

Answer 4

For growth or to produce replacement cells.

Question 5

Body cells have how many sets of chromosomes?

Answer 5

Two.

Question 6

Sex cells (gametes) have how many sets of chromosomes?

Answer 6

One.

Question 7

Cells where divide to form gametes?

Answer 7

In the reproductive organs - testes and ovaries i n humans.

Question 8

What type of cell division occurs to form gametes?

Answer 8

Meiosis.

Question 9

What happens to a cell when it divides to form gametes?

Answer 9

Copies of genetic information are made.

Then the cell divides twice to for four gametes, each with a single set of chromosomes.

Question 10

True or false, when gametes join at fertilisation two body cells with new pairs of chromosomes are formed.

Answer 10

False, a single body cell with new pairs of chromosomes is formed.

Question 11

After fertilisation, a new individual develops by what process?

Answer 11

Mitosis.

Question 12

Most types of animal cells differentiate when?

Answer 12

At an early stage.

Question 13

Many plant cells differentiate when?

Answer 13

Many maintain the ability to differentiate throughout life.

Question 14

In many mature animals, cell division is mainly limited to what?

Answer 14

To repair and replacement.

Question 15

Where can human stem cells be found?

Answer 15

Human embryos and adult bone marrow.

Question 16

Stem cells can be made to do what?

Answer 16

They can be made to differentiate into many different types of cells, eg: nerve cells.

Question 17

Human stem cells have what ability?

Answer 17

To develop into any type of human cell.

Question 18

Treatments with stem cells can treat what, for example?

Answer 18

Paralysis.

Question 19

How are the cells of the offspring produced in asexual reproduction?

Answer 19

By mitosis.

Question 20

What can be said about the alleles of the offspring in asexual reproduction?

Answer 20

They are identical to the parent.

Question 21

Sexual reproduction gives rise to variation, why?

Answer 21

When the gametes fuse, one of each pair of alleles comes from each parent.

Question 22

In the human body, one of the 23 chromosome pairs carries the genes that determine sex. What are the combinations in humans?

Answer 22

In females the sex chromosomes are the same (XX); in males the sex chromosomes are different (XY).

Question 23

Some characteristics are determined by a single…

Answer 23

…gene.

Question 24

A gene may have different forms known as…

Answer 24

…alleles.

Question 25

A dominant allele is what?

Answer 25

An allele that controls the development of a characteristic when only present on one of the chromosomes in that pair.

Question 26

A recessive allele is what?

Answer 26

An allele that controls the development of a characteristic when the dominant allele is not present.

Question 27

Chromosomes are made up of what?

Answer 27

Large molecules of DNA (deoxyribo nucleic acid), which has a double helix structure.

Question 28

A gene is what?

Answer 28

A small section of DNA.

Question 29

Each gene codes for a particular combination of...

Answer 29

...amino acids which make a specific protein.

Question 30

Every person except from who have unique DNA?

Answer 30

Identical twins.

Question 31

DNA fingerprinting is a way of doing what?

Answer 31

Identifying people due to their DNA being unique.

Question 32

True or false, all disorders are inherited.

Answer 32

False, only some disorders are inherited.

Question 33

Polydactyl is what?

Answer 33

A genetic disorder which causes the growth of extra fingers or toes. It is caused by the dominant allele therefore can be passed on by one parent having the gene.

Question 34

Cystic fibrosis is what?

Answer 34

A disorder of cell membranes. It must be inherited by both parents who must be carriers but do not have the disorder themselves. It is caused by the recessive allele of the gene.

Question 35

True or false, we can now screen embryos for the alleles that cause genetic disorders.

Answer 35

True.