Cell Division

Question 1

What does the cell cycle describe?

Answer 1

The life of a cell

Question 2

What is the period called where the cell is not dividing?

Answer 2

Interphase

Question 3

What is the period called when a cell divides?

Answer 3

Mitosis

Question 4

What is the longest phase in a cell’s life cycle?

Answer 4

Interphase

Question 5

What % is a cell’s life spent in interphase?

Answer 5

90%

Question 6

What is the cell like at the beginning of interphase?

Answer 6

The cell is very active, producing new organelles and chemicals needed for growth

Question 7

What does the cell do at the end of interphase?

Answer 7

The chromosomes make identical copies of themselves- double stranded chromosome

Question 8

What is the next phase after interphase?

Answer 8

Prophase

Question 9

What happens in the cell during prophase?

Answer 9

• The chromatin condenses
• Chromosomes become visible as a double stranded structure
• Spindle fibres appear in cytoplasm
• Nucleolus disappears
• Nuclear membrane starts to break down

Question 10

What is the next phase after prophase?

Answer 10

Metaphase

Question 11

What occurs in the cell during metaphase?

Answer 11

• Nuclear membrane is broken down
• Chromosomes line up across the centre of the cell
• Spindle fibres from each pole attach to each chromosome at the centromere

Question 12

What occurs after metaphase?

Answer 12

Anaphase

Question 13

What occurs in the cell during anaphase?

Answer 13

• Spindle fibres contract- centromere splits
• One chromosome from each double-stranded chromosome is pulled to opposite poles of the cell
• The four chromosomes pulled to each pole have identical sets of genes

Question 14

What is the next phase after anaphase?

Answer 14

Telophase

Question 15

What occurs in the cell during telophase?

Answer 15

• The four chromosomes at each pole elongate to form chromatin
• The spindle fibres break down
• Nucleolus re-forms
• Nuclear membrane forms around the chromatin at each pole

Question 16

What occurs in animal cells to produce new cells?

Answer 16

A cleavage furrow

Question 17

What occurs in plant cells to produce new cells?

Answer 17

• Small membrane enclosed sacs called vesicles gather in the area between the two nuclei
• These vesicles form the cell plate
• Two cell walls form from the cell plate

Question 18

What is the function of mitosis in unicellular organisms?

Answer 18

-Method of reproduction for amoeba

Question 19

What is reproduction without the joining of two cells called?

Answer 19

Asexual reproduction

Question 20

What is the function of mitosis in multicellular organisms?

Answer 20

• Produces new cells

- Growth and renewal and repair of cells

Question 21

What is cancer?

Answer 21

Is a group of disorders in which certain cells lose their ability to control both the rate of mitosis and the number of times mitosis takes place.

Question 22

What are malignant tumours?

Answer 22

Uncontrolled multiplication of abnormal cells

Question 23

What is movement of these cancer cells called?

Answer 23

Metastasis

Question 24

What causes cancer?

Answer 24

When normal genes are altered to form cancer-causing genes called oncogenes

Question 25

Name some cancer causing agents.

Answer 25

Carcinogens- cigarette smoke, asbestos fibres, ultraviolet radiation and some viruses

Question 26

What is meiosis?

Answer 26

Form of nuclear division in which the daughter nuclei contain half the chromosome number of the parent nucleus

Question 27

How many chromosomes do human cells have?

Answer 27

46 chromosomes

Question 28

Where does meiosis occur?

Answer 28

In the ovaries and testes

Question 29

What is the two functions of meiosis in multicellular organisms?

Answer 29

• Sexual reproduction without increasing number of chromosomes in offspring
• Allows new combinations of genes- variation