Cell Divison

Question 1

What is cell continuity?

Answer 1

All cells develop from pre-existing cells

Question 2

What are the two types of cell division?

Answer 2

Mitosis and meiosis

Question 3

How many daughter cells are formed by mitosis?

Answer 3

2 daughter cells

Question 4

How many daughter cells are formed by meiosis?

Answer 4

4 daughter cells

Question 5

What are the daughter cells of mitosis?

Answer 5

Identical

Question 6

What are the daughter cells of meiosis

Answer 6

Variations

Question 7

What are chromosomes?

Answer 7

Coiled threads DNA/protein found in the nucleus and are visible in the nucleus at cell division

Question 8

What is chromatin?

Answer 8

Unraveled long thin threads of DNA [not dividing]

Question 9

What is a gene?

Answer 9

It is a short section of DNA which contains the instructions for the formation of protein

Question 10

What are many of the proteins produced by genes?

Answer 10

Enzymes

Question 11

What kind of features to genes control?

Answer 11

Eye colour, production of skin pigment [melanin], shape of face, number of fingers

Question 12

In plants, what do genes control?

Answer 12

Petal colour, leaf shape, fruit taste

Question 13

What is a haploid cell and symbol

Answer 13

It has one set of chromosome ie it has only one of each type of chromosome in the nucleus
N=2

Question 14

What is a diploid cell and symbol?

Answer 14

It has two sets of chromosomes ie they are in pairs known as homologous pairs
Symbol : 2n=4

Question 15

What is the cell cycle composed of [different phases]

Answer 15

Interphase, prophase, metaphase, anaphase, telophase

Question 16

What are the different phases of mitosis

Answer 16

Prophase, metaphase, anaphase, telophase

Question 17

Where does mitosis take place?

Answer 17

In somatic cells

Question 18

What are somatic cells?

Answer 18

Cells that are not associated with the reproductive system

Question 19

What occurs in interphase?

Answer 19

The cell isn’t dividing, it is preparing for mitosis.
All DNA is duplicated
New cell organelles are made [eg, mitochondria]
A store of ATP energy is built up

Question 20

What occurs in prophase?

Answer 20

Chromatin shortens and thickens to form chromosome
Nuclear membrane breaks down
Centrioles move towards north and South Poles
The chromosomes continue to contract until it can be seen that each single chromosome is actually composed of 2 halves called sister-chromatids joined at a point called the centromere

Question 21

What occurs in metaphase?

Answer 21

All chromosomes line up along the equator of the cell

The centrioles produce spindle fibers [made of protein] that attach to the chromosomes at the centromeres

Question 22

What occurs in anaphase?

Answer 22

The spindle fibers contract pulling sister chromatids apart

Each is now called a chromosome

Question 23

What occurs in telophase?

Answer 23

Cell membrane contracts along the middle of the cell
A new nuclear membrane forms around each set of chromosomes
A groove called the cleavage furrow [in animal cells] and cell plate [in plant cells] appears at the equator of the cell
The cell membrane tightens so much that the cell divides into two daughter cells
The centrioles duplicate
The nuclear membrane is complete and the chromosomes unravel into chromatin

Question 24

Why is interphase not a resting phase in the cell cycle?

Answer 24

The cell is still functioning during this phase ; it is preparing for mitosis.

Question 25

What is a homologous pair?

Answer 25

Consists of two chromosome that have genes for the same features at the same positions

Question 26

What is the function of mitosis in unicellular organisms?

Answer 26

It is a form of asexual reproduction eg amoeba

Question 27

What is the function of mitosis in multicellular organisms?

Answer 27

Form of growth and repair

Question 28

What are the functions of meiosis?

Answer 28

Produces gametes It halves the chromosome number in gametes so that at fertilisation the correct chromosome number is achieved Produces genetic variations thigh sexual reproduction

Question 29

Give an example of meiosis

Answer 29

Egg + sperm n= 23 | This ensures when egg and sperm fuse, 2n=46

Question 30

What is cancer?

Answer 30

Cancer is the uncontrolled growth of cells due to damaged DNA

Question 31

How is cancer caused?

Answer 31

It is caused when normal genes are altered or mutated to form cancer causing genes called oncogenes

Question 32

What are carcinogens?

Answer 32

They are any environmental factor which mutates DNA

Question 33

How does the genetic damage in cancer be inherited or caused by?

Answer 33

Carcinogens

Question 34

What are three carcinogens/causes of cancer

Answer 34

Chemicals, radiation and viruses

Question 35

How do chemicals cause cancer?

Answer 35

Nicotine in cigarettes can lead to lung cancer

Question 36

How does radiation cause cancer?

Answer 36

Uv radiation from the sun = skin burnt - risk of skin cancer increased X Ray's damage dividing cells

Question 37

How do viruses cause cancer?

Answer 37

Some damage oncogenes of cells which may cause cancer eg, some forms of liver cancer may be due to the presence of hepatitis

Question 38

What is a tumour?

Answer 38

It is a cluster/lump of cells that have grown out of control because the cell lost control of mitosis

Question 39

There are two types of tumours, what are they

Answer 39

Benign tumour and malignant tumour

Question 40

What is a benign tumour and give an example

Answer 40

A tumour that will eventually stop growing and will not invade other tissues eg, skin tags, warts

Question 41

What are malignant tumours?

Answer 41

Cancerous tumours that will not stop growing and can invade other tissues and move from place to place

Question 42

What are the treatments of cancer?

Answer 42

Chemotherapy - slows mitosis Surgery - removes affected cells Radiation

Question 43

What are two DNA processes in interphase?

Answer 43

Replication | Transcription

Question 44

After telophase of mitosis, how do 1.animal cells and 2. Plant cells split in two?

Answer 44

Animal - cleavage furrow appears at equator of cell, cell membrane tightens so much it divides Plant - cell plate appears at equator and cell membrane tightens so much it divides

Question 45

Name two types of bio molecules that are produced in the cell during interphase of the cell cycle

Answer 45

Protein | Nucleic acid

Question 46

Name two changes that will have occurred in the cell by the end of interphase

Answer 46

DNA duplicated | Disappearance of nuclear membrane

Question 47

Suggest why human red blood cells do not undergo cell division?

Answer 47

No nucleus

Question 48

Give a cellular process that occurs during interphase?

Answer 48

Replication Respiration Protein synthesis

Question 49

State a function of spindle fibres

Answer 49

Cause centromeres to split and divides genetic material in cell

Question 50

How do spindle fibres carry out their function?

Answer 50

Attach to chromosomes at centromeres and in anaphase they Contract and pull chromosome - separating them

Question 51

Give one location where mitosis occurs in flowering plants

Answer 51

Meristematic tissue

Question 52

Give a role of chromosomes

Answer 52

Carries genes

Question 53

Name one organelle that is replicated at this stage of the cell cycle

Answer 53

Mitochondrial

Question 54

Give ways in which mitosis differs from meiosis?

Answer 54

Mitosis - two daughter cells, identical | Meiosis - four daughter cells, contain variation

Question 55

To what are chromosomes attached in metaphase?

Answer 55

Spindle fibres

Question 56

Give a feature from a diagram which allows you to identify anaphase

Answer 56

Chromosomes are separated

Question 57

Explain the term diploid number

Answer 57

Number of chromosomes in pairs

Question 58

How do you know that metaphase is taking place from a diagram

Answer 58

Chromosomes located on equator

Question 59

What is the diploid number of nucleus undergoing mitosis when X X X X

Answer 59

Four