Cell division

Question 1

Where is genetic information found in a cell?

Answer 1

In the nucleus, contained within chromosomes.

Question 2

What are chromosomes made of?

Answer 2

Coiled strands of DNA.

Question 3

What is a gene?

Answer 3

A short section of DNA that codes for a specific protein and controls a characteristi

Question 4

How many pairs of chromosomes are found in human body cells?

Answer 4

23 pairs - 46 chrom in total

Question 5

Why do body cells have pairs of chromosomes?

Answer 5

Because one set is inherited from the mother and the other from the father.

Question 6

How many chromosomes do gametes (sex cells) have?

Answer 6

23 single chromosomes (half the normal number).

Question 7

23 single chromosomes (half the normal number).

Answer 7

A series of stages a cell goes through to grow and divide.

Question 8

What is the purpose of mitosis?

Answer 8

For growth, repair, and replacement of damaged cells, and in asexual reproduction.

Question 9

What does a nucleus contain

Answer 9

chromosomes

Question 10

WHat does a chromosome contain

Answer 10

Many genes

Question 11

What is mitosis?

Answer 11

single cell divides into two identical daughter cells

Question 12

Examples of some cells that divide by mitosis

Answer 12

hair and nail cells
skin cells
red and white blood cells

Question 13

what are the steps of Mitosis

Answer 13

1) DNA replicates to form two copies of each chromosome
2) the membrane around the nucleus breaks down, the chromosomes condense and move freely in the cytoplasm
3) the chromosomes line up in the middle of the cell (equator)
4) the cell pulls apart the chromosomes into 2 arms. these are pulled to separated ends of the cell
5) the membrane forms around the sets of chromosomes on either ends of the cell. This forms 2 nuclei
6) the cytoplasm and cell membrane divide. The cell has non-identical 2 new daughter cells

Question 14

what are the steps of the cell cycle?

Answer 14

1) each cell grows and makes new subcellular structures
2) DNA is copied and new chromosomes are made
3) mitosis

Question 15

Why are the daughter cells identical in mitosis?

Answer 15

Because they contain an exact copy of the parent cell’s DNA.

Question 16

In which type of organisms is mitosis important?

Answer 16

In multicellular organisms for growth and repair, and in single-celled organisms for asexual reproduction.

Question 17

How is mitosis different from meiosis

Answer 17

Mitosis produces two identical cells with a full set of chromosomes; meiosis produces four non-identical cells with half the chromosome number.

Question 18

What is a stem cell?

Answer 18

An undifferentiated cell that can divide and become many different types of specialised cells.

Question 19

Where are embryonic stem cells found?

Answer 19

In early embryos formed after fertilisation.
Human embryos and adult bone marrow

the umbilical cord of a newborn baby

Question 20

What can embryonic stem cells do?

Answer 20

They can differentiate into any type of cell in the body.

Question 21

Where are adult stem cells found?

Answer 21

In bone marrow.

Question 22

What can stem cells be used to treat?

Answer 22

Paralysis and diabetes

treating conditions where cells are damaged or not working properly
used to replace damaged cells

Question 23

Where are stem cells found? - plants

Answer 23

meristems of plants

Question 24

Advantages of stem cells?

Answer 24

They can be taken without hurting
Will provide vital clues about how tissues develop
Could treat Parkinson’s, Alzheimer’s, heart disease, strokes, arthritis, burns etc
replace faulty cells

Question 25

Disadvantages of stem cells?

Answer 25

Use of embryos is unethical Embryonic stem cell research = murder Immune system might recognise stem cells as foreign and be rejected and die transfer of viral infections

Question 26

What are embryonic stem cells?

Answer 26

stem cells from human embryos that can make all types of cells

Question 27

What can adult stem cells form?

Answer 27

A limited range of cells, e.g. blood cells.

Question 28

What can meristem stem cells be used for?

Answer 28

To clone plants quickly with desirable features, such as disease resistance.

Question 29

what is therapeutic cloning?

Answer 29

A process where an embryo is created with the same genes as a patient so its stem cells won’t be rejected. A cloned embryo of the patient may be made and used as a source of stem cell

Question 30

Why is therapeutic cloning beneficial?

Answer 30

the stem cells from the cloned embryo will not be rejected by the patient’s body, so they could be very useful in treating the patient.

Question 31

How do scientists use stem cells to create healthy organs that replace faulty ones?

Answer 31

take the stem cells from the patient ( e.g. bone marrow) remove or fix a faulty gene insert the modified nucleus into a donor egg cell that has had the nucleus removed.This egg cell now thinks it’s been fertilised so it develops into an embryo Each cell in the embryo contains the DNA from the patient but without the faulty gene = embryonic stem cells remove the stem cells from the embryo and make them differentiate into the organ

Question 32

Advantages of stem cells for plants

Answer 32

rare species can be cloned to protect them from extinction - large numbers of identical crop plants with special features such as disease resistance, can be made

Question 33

Give two potential uses of stem cells in medicine.

Answer 33

Replacing damaged tissue or organs Treating diseases like diabetes or spinal cord injuries

Question 34

Give two problems with using embryonic stem cells.

Answer 34

Ethical concerns about embryo destruction Risk of uncontrolled cell growth or infection transfer