Ch.14 - Cell Division

Question 1

What is cell continuity?

Answer 1

Cell continuity means that all cells develop from pre-existing cells. (When a new cell forms, it forms all the materials it needs, it grows larger and it reproduces to form new cells.)

Question 2

What are chromosomes?

Answer 2

Chromosomes are coiled threads of DNA and protein that become visible in the nucleus during cell division.

Question 3

What is chromatin?

Answer 3

Chromatins are long, thin threads of chromosomes that occur during the interphase.

Question 4

What is a gene?

Answer 4

A gene is a section of DNA that contains the instructions for the formation of a protein.

Question 5

What is a haploid and diploid cell?

Answer 5

A haploid cell has one set of chromosomes, signified by n. A diploid cell has 2 sets of chromosomes, signified by 2n.

Question 6

What is a homologous pair?

Answer 6

A homologous pair is 2 chromosomes of similar size with the same sequence of genes.

Question 7

What is the cell cycle?

Answer 7

The cell cycle is the changes that take place in a cell during the period between one cell division and the next.

Question 8

What is mitosis?

Answer 8

Mitosis is a form of nuclear division in which one nucleus divides to form 2 nuclei, each containing the same number of chromosomes with identical genes.

Question 9

What is the function of mitosis in a unicellular organism.

Answer 9

In unicellular organisms, mitosis is used as a method of asexual reproduction.

Question 10

What is the function of mitosis in a multicellular organism?

Answer 10

In multicellular organisms, mitosis is responsible for growth, replacement and repair of cells.

Question 11

Draw the stages of mitosis in an animal with a diploid number of 2n=4. Explain the stages.

Answer 11

INTERPHASE IS NOT A PART OF MITOSIS.

Question 12

What is cancer?

Answer 12

Cancer 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 13

What are benign and malignant tumours?

Answer 13

In benign tumours, the cells stop dividing after some time. They are usually not life-threatening and they do not invade other tissues.
Malignant tumours are formed of abnormal cells as a result of cancer. Cancer results in an uncontrolled multiplication of abnormal cells. Malignant tumours may be life threatening. They have the potential for metastasis. They divide indefinitely.

Question 14

What is metastasis?

Answer 14

Metastasis is the process in which malignant cells spread to other parts of the body.

Question 15

What are oncogenes?

Answer 15

Oncogenes occur when normal genes are altered to form cancer-causing genes.

Question 16

What are carcinogens?

Answer 16

Carcinogens are cancer-causing agents such as cigarette smoke, UV radiation and asbestos fibres.

Question 17

What are the causes of cancer?

Answer 17

Oncogenes and carcinogens. Carcinogens are cancer-causing agents such as cigarette smoke, UV radiation and asbestos fibres. Oncogenes occur when normal genes are altered to form cancer-causing genes.

Question 18

What are cures for cancer?

Answer 18

Surgery, radiation (to burn out the cancer), and chemotherapy (to slow down mitosis).

Question 19

What is meiosis?

Answer 19

Meiosis is a form of nuclear division in which the 4 daughter nuclei contain half the chromosome number of the parent nucleus. (when meiosis takes place in a diploid cell, all daughter cells will be haploid)

Question 20

What are the functions of meiosis?

Answer 20

Meiosis allows for sexual reproduction, it halves the number of chromosomes so that the normal number may be restored at fertilisation.
New combinations of genes may be formed which gives rise to variation among organisms.

Question 21

What are the differences between mitosis and meiosis? (3)

Answer 21

In mitosis daughter cells have the same number of chromosomes. In meiosis, daughter cells have half the number of chromosomes of the parents. In mitosis, daughter cells have identical genes, in meiosis, daughter cells have different genes. In mitosis 2 cells are formed, in meiosis, 4 cells are formed.

Question 22

What is the difference between cell division in plant and animal cells?

Answer 22

In animal cells, a cleavage furrow forms and deepens to produce 2 new cells. In plant cells, vesicles gather to form a cell plate, which forms new cell walls.

Question 23

Where does meiosis occur in humans?

Answer 23

In males, meiosis occurs in the testes, in females, meiosis occurs in the ovaries.

Question 24

Describe a process involving DNA that takes place during interphase.

Answer 24

Towards the end of interphase, chromosomes produce identical copies of themselves. This duplication leads to the formation of double-stranded chromosomes.