Chapter 6- Cell Division

Question 1

Interphase

Answer 1

Long periods of growth and normal working separate divisions. These periods are called interphase and a cell spends the majority of its time in this phase
DNA is replicated
Protein synthesis occurs in cytoplasm
Mitochondria grow and divide, increasing in number in the cytoplasm
Chloroplasts grow and divide
The normal metabolic processes occur

Question 2

Three stages of interphase

Answer 2

G1- the first growth phase: proteins from which organelles are synthesised are produced and organelles replicate. The cell
increases in size
G2- the second growth phase: the cell continues to increase in size, stores are increased and duplicated DNA is checked for errors

Question 3

Miotic phase

Answer 3

Mitosis-the nucleus divides

Cytokinesis-the cytoplasm divides

Question 4

What is G0

Answer 4

The phase in which the cell leaves the cycle temporality or permanently

Question 5

Reasons to go into G0

Answer 5

Differentiation-A cell that becomes specialised to carry out a particular function. It will carry out this function indefinitely
The DNA of a cell may be damaged, in which case it is no longer viable. A damaged cell can no longer divide and enters a period of permanent cell arrest. As you get older the number of these cells in your body increases

Question 6

Checkpoints at various stages

Answer 6

G1-if satisfies these requirements it is triggered to begin DNA replication. If not it enters G0
G2- this checkpoint is at the end of G2 phase, before the start of the mitotic phase , DNA has to of been replicated without error
Spindle assembly checkpoint- at point where all spindles should be attached and aligned

Question 7

Importance of mitosis

Answer 7

For growth,tissue repair and asexual reproduction

Question 8

Prophase

Answer 8

Coil and condense to form chromosomes, the nucleoulus disappears, and nuclear envelope is broken down.
Micrtubles form spindle shaped structures linking the poles of the cell. Necessary to move the chromosomes into position. Centrioles migrate to poles of the cell. By end of prophase nuclear envelope has also disappeared

Question 9

Metaphase

Answer 9

The chromosomes are moved by the spindle fibres to form a plane in the centre of the cell, and then held into position

Question 10

Anaphase

Answer 10

The centromeres holding together the pairs of chromatids are separated and are pulled to opposite poles of the cells and form v shaped chromatids.

Question 11

Telophase

Answer 11

Chromatids have reached the poles and are now capped chromosomes, the two new sets of chromosomes and nuclear envelope reforms around them. Chromosomes start to uncoil smd nucleolus is formed

Question 12

Meiosis

Answer 12

Nucleus divides twice to produce four daughter cells

Question 13

Homoglogus chromosome

Answer 13

Each organisms cell contains two full sets of genes one from each parent

Question 14

Prophase 1

Answer 14

Chromosomes condense, the nuclear envelope disintegrates, the nucleoulus disappears and spindle formation begins.

Question 15

Metaphase 1

Answer 15

Chromosomes lie across the metaphase plate , but not as individual chromosomes

Question 16

Anaphase 1

Answer 16

Pulled to opposite poles of the cells but chromatids are held together. Can form recombinant chromatids. Genetic variation arises

Question 17

Telephase 1

Answer 17

Chromosomes assemble at each pole and nuclear membrane reforms. Chrmomsomss uncoil. Cells undergo cytokinesis

Question 18

Prophase 2

Answer 18

Still consist of two chromatids, condense and become visible, nuclear membrane breaks down

Question 19

Metaphase 2

Answer 19

More independent assortment more genetic variation as they lie across the middle

Question 20

Anaphase 2

Answer 20

V shaped chromosomes are formed same as in anaphase of mitosis

Question 21

Telephase 2

Answer 21

Chromatids assemble at the poles, form chromatin again nuclear envelope reforms and the nucleus becomes visible. Cytokinesis occurs forming four daughter cells in total.

Question 22

How are erythrocytes specialised?

Answer 22

Have a flattened bioconcave shape
No nuclei
Flexible so can squeeze through gaps

Question 23

How are neutrophils specialised

Answer 23

Multi lobed nucleus makes it easier for them to squeeze through gaps
Cytoplasm contains many lysosomes

Question 24

How are sperm cells specialised

Answer 24

Have a tail so are capable of moving and contain many mitochondria to help create energy to swim
Head contains enzymes which help penetrate the ovum

Question 25

How are palisade cells specialised

Answer 25

Contain chloroplasts which absorb lots of light
Thin cell walls to allow diffusion
Large vacuole to help maintain pressure

Question 26

How are root hair cells specialised

Answer 26

Large SA

maximises uptake of water

Question 27

How are guard cells specialised?

Answer 27

Thicker on one side so doesn’t change shape

Changes shape depending on water

Question 28

Types of tissues

Answer 28

Nervous tissue
Epethial tissue
Muscle tissue
Connective tissue

Question 29

Squamous epethielium

Answer 29

Forms lining of lungs

Flat layer of squamous cells

Question 30

Ciliated epethieulum cells

Answer 30

Hair like structures called cilia that move in a rhythmitic manner. Globlet cells are also present releasing mucus to trap any unwanted particles present in the air.

Question 31

What is cartilidge

Answer 31

A connective tissue found on the ear contains elastin and collagen

Question 32

What does epidermis cover

Answer 32

The surfaces of plants

Question 33

What are stem cells differentiated into in bone marrow

Answer 33

Erythrocytes and neutrophils

Question 34

What are produced in the meristems

Answer 34

Xylem vessels

Phloem siege tubes