4. Cell Division/Mitosis

Question 1

What is a unicellular organism?

Answer 1

Organisms such as bacteria and yeast are described as unicellular as they exist as single cells.

Question 2

What happens if a unicellular organism undergoes cell division?

Answer 2

This process can be used by unicellular organisms to asexually reproduce.

Question 3

Why do bacterial cells divide?

Answer 3

To reproduce

Question 4

Put the following structures in order from the largest to the smallest. Nucleus, DNA, gene, cell, chromosome, chromosome pair, and base

Answer 4

1. Cell
2. Nucleus
3. Chromosome pair
4. Chromosome
5. Gene
6. DNA
7. Base

Question 5

What is cell division?

Answer 5

Cell division is a process in which a parent cell makes a copy of itself, resulting in identical daughter cells.

Question 6

Which structure in animal, plant and yeast cells controls cell division?

Answer 6

The nucleus

Question 7

Define multicellular

Answer 7

Organisms made of more than once cell are described as multicellular. Examples of multicellular organisms include animals and most species of plants.

Question 8

Define chromosome

Answer 8

Chromosomes are thread-like structures that carry genetic information. They are found in the nucleus and are made of DNA.

Question 9

How many chromosomes are contained in the the daughter cells produced by the division of a body cell?

Answer 9

The same number of chromosomes as the parent cell.

Question 10

What is cell division used for in multicellular organisms?

Answer 10

In multicellular organisms the new cells are used for growth and repair of damage.

Question 11

A human body cell containing 46 chromosomes divides to produce two new body cells. How many chromosomes will each of the new body cells contain?

Answer 11

46

Question 12

Which structure in animal and plant cells contains the chromosomes?

Answer 12

The nucleus

Question 13

Define mitosis

Answer 13

Mitosis produces two diploid cells which each have the same number of chromosomes as original cell. The cer

Question 14

Define Diploid

Answer 14

A cell containing two complete sets of chromosomes, one from each parent. Compare with haploid.

Question 15

Define Haploid

Answer 15

A cell having a single set of unpaired chromosomes. Only the gametes (sex cells) are said to be haploid.

Question 16

Why is it important that all cells receive the full and correct information during mitosis?

Answer 16

It is important that all cells receive the full and correct information, otherwise they wouldn’t be able to function. It could cause an unfavorable mutation.

Question 17

Briefly describe the events that happen during cell division?

Answer 17

• Before cell division the DNA in the nucleus is long, thin and unwound.
• The DNA is copied. The DNA winds up into duplicated chromosomes.
• The duplicated chromosomes line up along the middle of the cell.
• The duplicated chromosomes are pulled apart.
  -Two nuclei are formed containing a full set of single chromosomes.
• Two daughter cells have been formed. - They have the same number of chromosomes as the parent cell.

Question 18

What happens if the cells in part of a multicellular organism divide uncontrollably?

Answer 18

The result is a large mass of cells called a tumour.

Question 19

When does a tumour become cancerous?

Answer 19

A tumour cell becomes cancerous when it invades surrounding body tissue.

Question 20

So why do healthy cells start to divide uncontrollably?

Answer 20

If the DNA in a cell gets damaged these instructions get broken and a cell can start to behave in a strange way.

Question 21

Usually cancer is a disease of old age. But what things can damage the DNA in a cell?

Answer 21

UV Light <sunlight>, smoking, alcohol, obesity, an unhealthy diet and lack of exercise.</sunlight>

Question 22

An investigation was carried out into the growth of a bacterial culture. The numbers of
bacteria were counted every 30 minutes and results are shown in the table below.

What happens to the number of bacteria every 30 minutes?

Answer 22

**The number doubles every 30 minutes **

(HINT- consider are the numbers going up/down, then for a pattern in the number sequence)

Question 23

Can you predict how many bacteria there would be at 180 minutes?

Answer 23

120 mins = 48
150 mins = 96 (48 x 2)
180 mins = 192 (96 x 2)
192 bacterial cells

Question 24

Why do living things make new cells?

a. Energy and repair
b. Growth and repair
c. Growth and energy
d. Growth, energy and repair

Answer 24

B Growth and Repair

Question 25

The process which makes new cells is called…

a. Cell division
b. Cell multiplication
c. Respiration
d. Photosynthesis

Answer 25

A Cell Division

Question 26

After cell division what is produced?

a. Two identical cells
b. Three identical cells
c. Two non-identical cells
d. Three non-identical cells

Answer 26

A Two identical cells

Question 27

Compared to the original parent cell. How many chromosomes do the daughter cells have?

a. Half the number of chromosomes
b. Same number of chromosomes
c. Twice the number of chromosomes
d. Four times the number of chromosomes

Answer 27

B - The same number of chromosomes

Question 28

What disease is caused by uncontrolled cell division?

a. Diabetes
b. Haemophilia
c. Cancer
d. Heart disease

Answer 28

C = Cancer

Question 29

What are stem cells

Answer 29

They are unspecialised master cells. They aree cells from which all others mature

Question 30

What is special about animals like starfish and salamanders?

Answer 30

They can regenerate their limbs, tails, or even parts of internal organs, such as the liver.
We know that stem cells are essential for this regeneration but just how they do it at the genetic level is a mystery.