Cell division

Question 1

interphase

Answer 1

majority of the cell life

Question 2

interphase 3 stages

Answer 2

G1 phase
S phase
G2 phase

Question 3

G1 phase

Answer 3

cell increases in size and new biomass is made

Question 4

s phase

Answer 4

DNA replicates by semiconservative DNA replication

Question 5

G2 phase

Answer 5

cell is ready for division synthesis and stores of ATP and new organelles synthesised

Question 6

nuclear division

Answer 6

period when nucleus divides into 2 or 4

Question 7

cell division

Answer 7

-cytokinesis
-division of the cytoplasm to produces 2/4 new cells

Question 8

gene definition

Answer 8

section of DNA that codes for one polypeptide

Question 9

chromosome definition

Answer 9

independent DNA molecule which has been supercoiled into a condensed form

Question 10

homologous chromosome definition

Answer 10

-have the same genes in the same gene loci but may have different alleles of the genes

Question 11

example of diploid cell

Answer 11

skin cell

Question 12

example of haploid cell

Answer 12

sperm cell

Question 13

mitosis is used for:

Answer 13

-increasing cell numbers and growth of an organism
-repair of damaged tissues
-replacement of worn out cells

Question 14

4 stages of mitosis

Answer 14

prophase
metaphase
anaphase
telophase

Question 15

prophase

Answer 15

1. nuclear membrane starts to break down
2. centrioles start to move to the poles of the cell and make spindle fibres
3. chromosomes supercoil and condense and become visible
4. each chromosome appear as 2 identical sister chromosomes joined at centromere

Question 16

Metaphase

Answer 16

Centromeres have fully made the spindle fibres
Chromosomes attached to spindle fibres by the centromere
Chromosome align down the middle

Question 17

Anaphase

Answer 17

Spindle fibres shorten
Centromere splits
Identical sister chromatids are pulled to opposite poles
Making a v shape

Question 18

Telophase

Answer 18

Nuclear membrane starts to reform around each set of chromosomes
Chromatids uncoil

Question 19

Cytokinesis

Answer 19

Cytoplasm divides forming two daughter cells

Question 20

How do bacteria replicate ?

Answer 20

Replication of circular DNA
Division of cytoplasm to produce two daughter cells
Each with a singular copy of DNA

Question 21

How do viruses replicate ?

Answer 21

1.Virus attaches to cell
2.Protein moleucles on the capsid attached to the cell surface membrane of the hosts cells.
3.The virus genetic material enters the cells cytoplasm.
4.The viruses nucleic acid is inserted into the host cells own nuclear DNA.
5.The host cell is now infected.
6.The viral DNA is transcribed and translated into proteins
7.The cell replicates the viral DNA
8.The genetic material and proteins coats are assembled into virions
9.Eventually these virions burst out of the cell, often destroying the host cell

Question 22

Mototic index

Answer 22

MI= (no. of cells with condensed chromosomes/total number of cells) x100

Question 23

Formula for serial dilution

Answer 23

M1 x V1 = M2 x V2

Question 24

How many daughter cells does meiosis produces

Answer 24

4 genetically different daughter cells

Question 25

divisions in meiosis

Answer 25

first divisions the homologous chromosomes pair up and separate
second division the chromatids are seperated

Question 26

two processes which increase genetic variation

Answer 26

crossing over
independent segregation

Question 27

crossing over

Answer 27

-homologous chromosomes form a bivalent
-chiasmata form
-equal length of chromatids are exchanged
-produces new combinations of alleles

Question 28

independednt segregation

Answer 28

homologous chromosomes attach to spindle fibres and they pair up side by side and can be reshuffled in any combination