Chapter 14 - Cell Divison

Question 1

What is cell continuity

Answer 1

All cells develop from pre-existing cells

Question 2

What are chromosomes

Answer 2

They are made of DNA and protein usually seen as chromatin in the nucleus humans have 46 chromosomes

Question 3

What is chromatin

Answer 3

Long thin thread

Question 4

What are genes

Answer 4

they are units of inheritance

each chromosome has thousands of genes

Question 5

What is a haploid cells

Answer 5

Haploid cells only contain one set of chromosomes

haploid is symbolised by the latter n and the number of chromosomes in humans egg and sperm is haploid N equals 23

Question 6

What is a diploid cell

Answer 6

Diploid cells contain two sets of chromosomes
they are in pairs home - homologous pairs
one of the pairs comes from the father the other from the mother diploid symbolise as 2n
in humans cells are diploid 2N equals 46

Question 7

What is interphase

Answer 7

Interphase is the phase in the cell cycle when the cell is not dividing
this accounts for 90% of the cell cycle
chromosomes appear as chromatin
cells are very active
organelles chemicals for growth proteins and enzymes are produced

Question 8

What is mitosis

Answer 8

Mitosis is a form of nuclear division in which one nucleus divides to form two nuclei
Each containing identical sets of chromosomes
two new cells are formed called daughter cells

Question 9

Name the four phases

Answer 9

Prophase
metaphase
anaphase
Telophase

Question 10

What happens during prophase

Answer 10

Chromatin begins to contract
chromosomes become visible as double-stranded structures
the nuclear membrane breaks down
fibers is performing

Question 11

What happens during metaphase

Answer 11

The nuclear membrane completes its breakdown

spindle fibres on each pole of the cell attaches to the centromere chromosomes line up in the equator of the cell

Question 12

What happens during anaphase

Answer 12

The spindle fibers contract
The centromeres split
One strand from each chromosomes goes to opposite poles of the cell
The chromosomes duplicate here

Question 13

What happens during telophase

Answer 13

The four chromosomes on each pole begin to lengthen making them hard to distinguish
The spindle fibers break down
The nucleolus begins to form
A nuclear membrane forms around the cells

Question 14

Function of mitosis in unicellular organisms

Answer 14

Method of reproduction

E.g. amoeba

Question 15

Functions of mitosis in multicellular organisms

Answer 15

Produces new cells growth and repair is the cell

Question 16

What is cancer

Answer 16

Cancer is when a group of cells lose their ability to control the rate of mitosis

Question 17

Name the two types of tumours

Answer 17

Benign - non life threatening, don’t invade other tissues, stop after a while
malignant - life-threatening, invade other tissue, continue to divide continuously

Question 18

2 causes of cancer

Answer 18

Normal genes altered to form cancer-causing genes

Cancer causing agents (carcinogens) e.g. smoking

Question 19

What treatments are available for cancer

Answer 19

Surgery chemotherapy radiation

Question 20

What is meiosis

Answer 20

Nuclear division where four daughter nuclei are formed with half the number of chromosomes of the parent nucleolus

Question 21

What are the functions of meiosis

Answer 21

Sexual reproduction

variation in genetic material - differences between organisms of the same species