Exercise 4

Question 1

2 In the human, how many new cells are produced from mitosis and how many chromosomes are in each new cell?

Answer 1

2. Two new daughter cells will be produced each with the same number of chromosomes as the parent cell. In humans this number is 46 individual chromosomes or 23 pairs. These two new daughter cells are said to be identical to the parent cell as they contain the same number and kind of chromosomes as the original parent cell. We refer to 46 as the diploid number of chromosomes, the symbol of which is 2n.

Question 2

3. What is the name given to the type of nuclear division involving sex cells (gametes)?

Answer 2

3. Meiosis is a type of nuclear division that produce sex cells from germ cells.

Question 3

4. In the female and male human,what are the names given to the new cells formed and how many chromosomes are in each of these cells?

Answer 3

4. Cells called eggs or ova in the female and sperm in the male, are produced from the division of primitive cells referred to as germ cells. Each egg or sperm will contain only half the number of chromosomes, 23 in humans. We refer to 23 as the haploid number of chromosomes, the symbol of which is n.

Question 4

5. What are the three aspects of the cell and approximately how long does each last?

Answer 4

5. The three stages of the cell cycle are:
   i) interphase
   ii) mitosis
   iii)cytokinesis
   The cell cycle varies in length depending on the cell involved. In general the cell cycle lasts anywhere from 18-24 hours. Mitosis and cytokinesis combined only last for approximately 1-2 hours, and the remainder of the time is spent in interphase.

Question 5

Define and describe interphase

Answer 5

6. Interphase is defined as the interval of time between cell divisions. It is not a resting stage but a working stage as it is actually the time in which cellular metabolism is taking place. In interphase, just before cell division begins, chromosomes shorten and thicken and DNA will replicate. In the human this means that 46 chromosomes are now 92.

Question 6

7. Name the four phases of mitosis.

Answer 6

7. The four phases of mitosis are:
   i) Prophase
   ii) Metaphase
   iii) Anaphase
   iv) Telophase

Question 7

What is the name given to the type of nuclear division of a somatic (body) cell that ensures growth or repair of tissue?

Answer 7

1. Mitosis is a type of nuclear division that ensures growth or repair of a body cell.