B2 Cell Division

Question 1

Gene

Answer 1

Section of DNA that codes for a specific protein

Question 2

Chromosome

Answer 2

A molecule of DNA consisting of a group of thousands of genes

Question 3

Genome

Answer 3

The collections of chromosomes that define an individual (23 pairs, 46 in total for humans)

Question 4

Nucleus

Answer 4

Organelle containing the DNA that controls the activity in the cell

Question 5

Cell

Answer 5

The smallest functional unit of an organism

Question 6

Why does our body need mitosis?

Answer 6

• Growth
• Repair
• Reproduction

Question 7

What are the three stages of the cell cycle?

Answer 7

1) Replication
2) Mitosis
3) Division

Question 8

Replication

Answer 8

All of the organelles and chromosomes in the cell are copied

Question 9

Mitosis

Answer 9

The contents of the cell are rearranged.
The chromosomes are pulled apart to each end of the cell.

Question 10

Division

Answer 10

The cytoplasm and cell membrane divide into two identical daughter cells

Question 11

How fast does the cell cycle happen?

Answer 11

24 hours to several years depending on the type of cell and the life stage:
- Foetus -> very fast
- Baby -> fast
- Child -> slowing
- After puberty -> slow (repair/replace only)

Question 12

What is differentiation and how does it work?

Answer 12

Cells differentiate by turning some of their genes off and some of their genes on. The combination of working and inactive genes decides what organelles the cell has and what the cell does

Question 13

What are stem cells?

Answer 13

An undifferentiated cell which could turn into any Specialised cell in an organism.

Question 14

Stem cells in plants

Answer 14

• Can differentiate through their lives (unlike animals)
• Found in the meristem

Question 15

Embryonic stem cell

Answer 15

• Early stages of the embryo
• Can differentiate into most types of cell

Question 16

Adult stem cell

Answer 16

• Taken from adult bone marrow
• Can differentiate into some types of cells (e.g. blood cells)

Question 17

Why is being able to clone large numbers of plants useful?

Answer 17

• In horticulture, we can produce large numbers of plants to sell.
• In agriculture, we can produce identical crops with special features, such as disease resistance.

Question 18

Therapeutic cloning

Answer 18

A process that produces an embryo with genes that are identical to the patient’s

Question 19

What are the risks of therapeutic cloning?

Answer 19

• Infections
• Ethical or religious objections