Cell Division

Question 1

What are chromosomes made up of?

Answer 1

Chromosomes consist of DNA molecules combined with proteins. They contain genes which provide the instructions for protein synthesis

Question 2

What is a gene?

Answer 2

A section of DNA which codes for a protein

Question 3

How many chromosomes are found in the nucleus of human body cells?

Answer 3

46

Question 4

How many chromosomes are found in the nucleus of gametes?

Answer 4

23

Question 5

How are chromosomes arranged in the nucleus of a body cell?

Answer 5

Arranged in pairs: 46 Chromosomes form 23 pairs

Question 6

What are the main three stages of the cell cycle

Answer 6

1. Replication of DNA and synthesis of organelles
2. Mitosis
3. Division

Question 7

Why is mitosis important?

Answer 7

• Produces identical cells which all have the same genetic information
• Produces additional cells for growth and repair

Question 8

Describe the first stage of the cell cycle

Answer 8

Longest Stage - Cells grow and increase in mass, replicate DNA and synthesise more organelles (e.g. mitochondria, ribosomes)

Question 9

Describe the second stage of the cell cycle

Answer 9

Each chromosome in a pair is pulled to opposite poles of the cell, then the nucleus divides.

Question 10

Describe the third stage of the cell cycle

Answer 10

The cytoplasm and cell membrane divide, two identical daughter cells are produced

Question 11

What is a stem cell?

Answer 11

An unspecialised cell which is capable of differentiating into other cell types and of self-renewal

Question 12

What is the function of stem cells in embryos?

Answer 12

Embryonic stem cells can replicate themselves and differentiate into many other types of cells.
Embryonic stem cells may be able to treat conditions such as paralysis and diabetes by dividing to replace damaged cells

Question 13

What is the function of stem cells in adult bone marrow?

Answer 13

Adult stem cells can differentiate into several cell types to replace dead or damaged tissues. For example, bone marrow stem cells can form many different types of blood cell

Question 14

What is the function of stem cells in plant meristems?

Answer 14

Meristem stem cells retain the ability to differentiate into any type of plant cell throughout their lifespan - they can differentiate into any cell which is required by the plant.

Question 15

What is therapeutic cloning?

Answer 15

A cloning method where an embryo is produced with the same genetic makeup as the patient.
The stem cells which originate from the embryo will not be rejected by the patient’s immune system, so can be used to treat certain medical conditions

Question 16

What are the advantages of cloning plants using meristem stem cells?

Answer 16

• Can prevent rare plants from becoming extinct
• Can produce large numbers of plant with a favourable characteristic
• Can produce identical plants for research

Question 17

What is asexual reproduction?

Answer 17

Producing new organisms from one parent only. These organisms are genetically identical to the parent

Question 18

What is a cancer Cell?

Answer 18

A cell that divides uncontrollably

Question 19

What is the cell cycle?

Answer 19

A sequence of growth and division that happens in cells. It includes interphase and mitosis, and leads to the production of two daughter cells that are identical to the parent cell

Question 20

What is a clone?

Answer 20

Offspring from asexual reproduction. All the cells in a clone are genetically identical to each other and to the parent’s cells

Question 21

What is a daughter cell?

Answer 21

New cell produced by cell division

Question 22

What is a diploid?

Answer 22

A cell with two sets of chromosomes

Question 23

What is DNA replication

Answer 23

The copying of the DNA within a cell.

Question 24

What is a haploid?

Answer 24

A cell with one set of chromosomes

Question 25

What is mitosis

Answer 25

The process of cell dividing to produce two daughter cells that are genetically identical to the parent.

Question 26

Multicellular

Answer 26

An organism that is made of many cells.

Question 27

What is a tumour?

Answer 27

Lump formed of cancer cells.

Question 28

What is differentiation?

Answer 28

When a group of similar things, such as cells, become different in form from each other

Question 29

What is growth?

Answer 29

A permanent increase in the number or size of cells in an organism

Question 30

Differentiate

Answer 30

To change into different types, for example when meristem cells differentiate into specialised cells such as xylem or root hair cells

Question 31

What is a root hair cell?

Answer 31

Cell found on the surface of plant roots that has a large surface area to absorb water and dissolved mineral salts quickly from the soil

Question 32

What is a xylem cell?

Answer 32

Cells that join with other xylem cells to form long, thick-walled vessels after they die. The vessels after they die. The vessels carry water and dissolved mineral salts through the plant

Question 33

What is cancer?

Answer 33

A disease caused by the uncontrolled division of stem cells in a part of the body?

Question 34

What is a stem cell?

Answer 34

Unspecialised cell that continues to divide by mitosis to produce more stem cells and other cells that differentiate into specialised cells