Cell Division

Question 1

What do all cells develop from?

Answer 1

Pre-existing cells

Question 2

What are the steps to form a new cell and how many are there?

Answer 2

3 steps to form a new cell

• Produce materials it will need
• Grow larger
• Reproduce to form a new cell

Question 3

What are chromosomes?

Answer 3

Structures in Nucleus, made of DNA and Protein

Question 4

What do we call chromosomes when they are not dividing?

Answer 4

Chromatin forms a number of clearly distinguishable chromosomes

Question 5

How many chromosomes does each species have?

Answer 5

Each species has a definite no. of Chromosomes, Humans = 46 chromosomes

Question 6

How many genes does each chromosomes have?

Answer 6

Each chromosomes has 1000s of genes

Question 7

Draw and label a pair of homologous chromosomes.

Answer 7

.

Question 8

What is a Haploid?

Answer 8

A Haploid cell has one set of chromosomes, i.e. has only one set of each type of chromosomes in the nucleus.

Question 9

What is Haploid symbolised by?

Answer 9

the letter n

Question 10

What is the number of chromosomes in the Haploid cell given as?

Answer 10

n=23

Question 11

What type of cell are humans eggs and sperm?

Answer 11

haploid n=23

Question 12

What is a diploid?

Answer 12

A Diploid has two sets of chromosomes, i.e. It has two of each type of chromosome in the nucleus

Question 13

How are chromosomes organised in a diploid cell?

Answer 13

Chromosomes are in pairs in diploid cell, called homologous pairs.

Question 14

How is a diploid symbolised as and what is the total no. of chromosomes in a diploid cell given as?

Answer 14

Diploid is symbolised as 2n and total no. of chromosomes in cell is given as 2n = 46

Question 15

Where do the chromosomes come from in a diploid cell?

Answer 15

In diploid cells, 1 chromosome from the homologous pair comes from the mother and the other comes from the father

Question 16

What is the cell cycle?

Answer 16

Describes the life of a cell. It includes the period between division when the cell is not dividing, called Interphase.

Question 17

What is the period when a cell divides called?

Answer 17

Mitosis

Question 18

What is interphase?

Answer 18

The period between division when the cell is not dividing

Question 19

How long is interphase?

Answer 19

Longest phase in cell cycle = 90% of a cells life is in interphase

Question 20

What are chromosomes called in interphase? What is one difference between them and chromosomes?

Answer 20

chromatin

not elongated

Question 21

What are cells like in interphase, what do they do?

Answer 21

Cell very active in Interphase, produces new mitochondria, chloroplasts etc. and chemicals needed for growth

Question 22

What is mitosis?

Answer 22

Mitosis is a form of nuclear division in which one nucleus divides to form two nuclei, each containing identicals sets of chromosomes.

Question 23

What are the two new cells called formed by mitosis? What is one feature of them?

Answer 23

Two new cells called daughter cells and they are IDENTICAL to each other

Question 24

What are the functions of mitosis in Unicellular Organisms?

Answer 24

Method of reproduction for Amoeba Reproduction that does not involve the joining of 2 cells is called asexual reproduction.

Question 25

What are the functions of mitosis in multicellular organisms?

Answer 25

Produces new cells, not new individuals | Responsible for growth and renewal and repair of cells

Question 26

what is important the body does to the rate of cell division?

Answer 26

Rate of cell division (mitosis) is carefully controlled

Question 27

What sometimes happens to a cell or group of cells in mitosis?

Answer 27

Sometimes a cell or group of cells lose the ability to control the rate of cell division

Question 28

What happens when a cell or group of cells loves the ability to control the rate of cell division?

Answer 28

They form a mass of cells called a tumour which can be benign or malignant

Question 29

What does benign mean?

Answer 29

Benign means kind, they are not life threatening and do not invade other tissues. E.g. warts, skin tags. Cells stop dividing after some time.

Question 30

What is cancer?

Answer 30

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 31

What are malignant tumours?

Answer 31

Uncontrolled multiplication of abnormal cells Malignant tumours (cancers) invade other cells and move around the body. Movement of these cells called Metastasis. Cancer cells divide indefinitely

Question 32

What is the movement of cells invaded by malignant cancers called?

Answer 32

metastasis

Question 33

What are the causes of cancer?

Answer 33

Caused when normal genes are altered to form cancer-causing genes called oncogenes. Brought about by cancer causing agents called carcinogens e.g. cigarette smoke, asbestos fibres, ultraviolet radiation and some viruses

Question 34

How can most cancers be cured?

Answer 34

Most cancers can be cured with radiation (burn out cancer), chemotheraphy (chemicals sllow down mitosis and surgery

Question 35

What is meiosis?

Answer 35

Meiosis is a form of nuclear division in which the daughter nuclei contain half the chromosome number of the parent nucleus.

Question 36

How many chromosomes do human cells have?

Answer 36

46

Question 37

Where does meiosis occur in humans and what does it do?

Answer 37

Meiosis occurs in the ovaries and testes to produce gametes called eggs and sperm so there are 23 chromosomes in each egg and sperm.

Question 38

How many chromosomes are there in each egg and sperm?

Answer 38

There are 23 chromosomes in each egg and sperm.

Question 39

How many functions of meisosis are in multicellular organisms?

Answer 39

2

Question 40

What does meiosis allow?

Answer 40

Allows sexual reproduction without increasing the number of chromosomes in the offspring. Allows new combinations of genes.

Question 41

What is the sentence to help you remember the 4 stages of mitosis?

Answer 41

I Party Monday And Tuesday | interface is not really a stage of mitosis [I]

Question 42

Draw a diagram of prophase

Answer 42

pg. 162 - 14.23

Question 43

How many stages of mitosis are there?

Answer 43

4 in total

Question 44

What happens in the prophase stage?

Answer 44

At end of Interphase, Chromosomes contract and become visible. Each chromosome appears as a duplicated strand. Fibres appear in cytoplasm. Nuclear membrane starts to break down.

Question 45

What happens at the end of Interphase?

Answer 45

The prophase stage

Question 46

What happens in metaphase?

Answer 46

Nuclear membrane broken down Chromosomes thicken even more Chromosomes line up across the centre of cell Fibres attach to chromosomes Each chromosome has 2 fibres attached, 1 from each side of the all.

Question 47

Draw a diagram of metaphase

Answer 47

.

Question 48

What happens in anaphase?

Answer 48

Fibres contract, chromosomes pulled apart Each strand is pulled to opposite end of cell Hence, identical set of genes pulled to each end of the cell.

Question 49

Draw a diagram of anaphase

Answer 49

.

Question 50

What happens in telophase?

Answer 50

Nuclear membrane forms around each of the 2 sets of chromosomes. Chromosomes elongate within each nucleus Mitosis is complete. Once complete, original cells divide to form 2 cells.

Question 51

Draw a diagram of telophase

Answer 51

.