1.1. Division and Differentiation of Human Cells

Question 1

What are the four levels of organisation in our bodies?

Answer 1

Cells -> Tissue -> Organs -> Systems

Question 2

What are stem cells?

Answer 2

They are unspecialised cells that have the ability to self renew and differentiate into a diverse range of specialised cells.

Question 3

What does pluripotent mean?

Answer 3

Able to differentiate into most of all cell types. (Embryonic stem cells)

Question 4

What does totipotent mean?

Answer 4

Able to differentiate into all cell types.

Question 5

What does multipotent mean?

Answer 5

Able to differentiate into closely related cells. (Tissue stem cells)

Question 6

What is an ethical issue to do with stem cells?

Answer 6

When doing research on stem cells it involves the destruction of the embryo. People see embryos as potential life so destroying a potential life is seen as unethical.

Question 7

What are somatic cells?

Answer 7

Cells derived from the differentiation of stem cells. They form several types of body tissue.

Question 8

How are somatic cells produced?

Answer 8

They are produced through cellular differentiation where a cell develops more specialised functions by expressing the specific genes needed for each cell type.

Question 9

What are germline cells?

Answer 9

They include gametes and the cells that produce the gametes (gamete mother cells).

Question 10

What are genes?

Answer 10

The basic unit of inheritance, many of which make up a chromosome; each carries the information needed to make a protein.

Question 11

What are chromatids?

Answer 11

One of the two identical replicas of a chromosome.

Question 12

What does diploid mean?

Answer 12

Has a double set of chromosomes which form cells.

Question 13

What does haploid mean?

Answer 13

Has a single set of chromosomes.

Question 14

Describe the process of mitosis.

Answer 14

Chromosomes appear in the nucleus, the chromosomes then shorten and appear as double threads joined at one point. The membrane around the nucleus disappears and the chromosomes line up at the centre of the cell. The chromatids are pulled apart and move to opposite sides of the cell. The nuclear membrane reforms round each group of chromatids and the cytoplasm divides. The two new cells now undergo a growth period before mitosis starts again in each cell.

Question 15

Describe the process of meiosis.

Answer 15

A diploid cell with 4 chromosomes exists. The chromosomes then replicate to make 4 identical copies of themselves where homologous chromosomes pair up and swap sections of DNA. The homologous pairs then line up at the centre of the cell and divide into daughter nuclei. The chromosomes then divide once more producing four haploid gametes.

Question 16

Which cells fall under the connective tissue category and why?

Answer 16

Blood cells, bone cells, cartilage cells, connect tissue together, located in between other tissue.

Question 17

Which cells fall under the epithelial tissue category and why?

Answer 17

Cells that line organs and skin cells, they line tubes, cavities and surfaces of structures throughout the body.

Question 18

Which tissue makes up most of the muscles in the body such as skeletal muscle, heart muscle?

Answer 18

Muscle tissue.

Question 19

Which tissue makes up the nervous system?

Answer 19

Nervous tissue.

Question 20

How do cancer cells form?

Answer 20

They form when cells divide uncontrollably as they do not respond to regulatory signals. They avoid being destroyed by the immune system and produce an abnormal amount of cells known as a tumour.