Chapter 23 - cell division

Question 1

Name the significance of mitosis

Answer 1

• growth -organisms increase by mitosis
• cell replacement- repairs and heals for maintenance
• genetic stability - daughter cells are identical to parent cells
• regeneration- missing limbs can grow back
• asexual reproduction - plant species, bacteria and animals propagated by mitosis

Question 2

Name the Principles of cloning

Answer 2

1. Take a cell
2. Remove the nucleus
3. Remove the egg cell and remove the nucleus
4. The nucleus from donor is then replaced into enucleated egg cell by electrical shock
5. The fused cell begins to divide and forms an embryo
6. The embryo is placed in the womb and left to develop
7. The new individual is now genetically identical

Question 3

State the social implication of cloning

Answer 3

1. Cloning animals might be advantageous

2. Cloning plants might be a great advantage

Question 4

Define cancer

Answer 4

Is a disease affecting the growth rate of cells leading to uncontrolled division which results in a tumours

Question 5

State the development of cancer

Answer 5

1. Stated with mutation in DNA
2. Leads to disturbance in activity of genes
3. Mutation damages ability to control rate if growth
4. Leads to uncontrollable mitosis
5. Many cancerous cells fails to differenciate into functional tissue cells and form tumours
6. Benign tumours are harmless
7. Malignant tumours invade surrounding cells
8. Cancer can be treated by radiation or surgery

Question 6

Name 9 factors that may increase risk of developing cancer

Answer 6

1. UV rays
2. Radiation
3. Exposure to carcinogens
4. Viral infections
5. Excessive fats
6. Excessive salts
7. Alcohol
8. Alpha and beta particles
9. Asbestos dust

Question 7

Define meiosis

Answer 7

Type of cell division by which four haploid cells are formed which are genetically different from each other

Question 8

The significance of meiosis

Answer 8

1. This is the basis of sexual reproduction

2. Genetic variation is possible

Question 9

Role of meiosis in sexual reproduction

Answer 9

1. Meiosis is a reduction division
2. Change diploid cells into haploid
3. Prevents zygote from having 92 chromosomes
4. Cause genetic variations

Question 10

Define mitosis

Answer 10

Type of cell division by which cells divide into two daughter cells forming identical cells with full set of chromosomes