Cell Division

Question 1

What is a haploid?

Answer 1

A haploid is a cell with a single set of unpaired chromosomes (n23)

Question 2

What is a diploid?

Answer 2

A cell with two complete sets of chromosomes (n46)

Question 3

What is a gamete?

Answer 3

A sex cell

Eg. Sperm, egg, pollen

Question 4

What is a zygote?

Answer 4

A zygote is formed when two gametes fuse together

Question 5

What is the significance of mitosis?

Answer 5

1) Growth of multicellular organisms

2) replacement of cells and tissue repair

3) Asexual reproduction

Question 6

What is gap 0?

Answer 6

Gap 0 is when a cell leaves the cell cycle

Question 7

Why might a cell leave the cell cycle?

Answer 7

A cell might enter G0 due to:

•Differentiation - cell becomes specialised

•Damaged DNA - stops spread of damaged DNA

• senescene - most normal cells can only divide around 50 times

Question 8

What is being checked at checkpoint G1?

Answer 8

Cell size
Nutrients
Growth factors
DNA damage

Question 9

What is being checked at G2?

Answer 9

Cell size
DNA replication
DNA damage

Question 10

What is the role of Histone?

Answer 10

Histone is a protein that DNA coils around allowing it to pack tightly together and protecting it. These coils then from chromatids.

Question 11

What is the significance of mitosis?

Answer 11

Growth of multicellular organisms
Replacement of cells and tissue repair
Asexual reproduction

Question 12

What happens to chromatin when other cell is about to divide?

Answer 12

It condenses

Question 13

What is the centromere?

Answer 13

The region where two chromatids join together

Question 14

What is cytokinesis?

Answer 14

Cytoplasmic division

Question 15

What occurs during the interphase of the cell cycle?

Answer 15

Energy stores increase
Cell grows in size
Organelles replicated
DNA copied

Question 16

What happens in the mitotic phase of the cell cycle?

Answer 16

The nucleus divides (Mitosis)
The cell divides (Cytokinesis)

Question 17

What are the 4 stages of mitosis?

Answer 17

Prophase (prepare)
Metaphase (middle)
Anaphase (apart)
Telophase (two)

Question 18

What happens at the prophase?

Answer 18

Chromosomes become visible
The nucleolus disappears
The nuclear membrane breaks down
Proteins form spindle fibres

Question 19

What happens during the metaphase?

Answer 19

The chromosomes are lined up at the cell’s equator. Spindle fibres form

Question 20

What happens at the anaphase?

Answer 20

The spindle fibres begin to shorten pulling the chromatids apart.

This pulls the sister chromatids to opposite poles of the cell

Question 21

What happens during telophase?

Answer 21

The chromatids have reached the poles of the cell. The nuclear membrane starts to reform and the nucleolus reappears.

Cytokinesis begins.

Question 22

What happens during cytokinesis?

Answer 22

Actin microfilaments causes the cell surface membrane to pinch inwards creating a furrow. This furrow grows as the cell membrane is pulled in until it fuses, creating two separate cells.

Question 23

What are the adaptations of erythrocytes (red blood cells)

Answer 23

Biconcave structure to increase SA
No nucleus to increase SA

Contain lots of haemoglobin to store more oxygen

Question 24

How are new xylem cells produced?

Answer 24

Produced in meristems by differentiating from stem cells

Question 25

Which stage of meiosis does crossing over occur?

Answer 25

Prophase 1

Question 26

Which stage of meiosis does independent assortment occur?

Answer 26

Metaphase 1 and 2

Question 27

What do neutrophils (white blood cells) do?

Answer 27

Ingest bacteria and some fungi via phagocytosis

Question 28

What are the adaptations of neutrophils?

Answer 28

Attracted to and travel to infection sites by chemicals Twice the size of erythrocytes Each neutrophil has a multi-lobed nucleus

Question 29

What do squamous epithelial cells do?

Answer 29

They make up the walls of alveoli and capillaries as well as the lining of intestines.

Question 30

What are the adaptations of squamous epithelial cells?

Answer 30

They are flat in shape to facilitate faster diffusion

Question 31

What is the role of smooth muscle tissue?

Answer 31

Propels substances along the walls of intestines, blood vessels, uterus

Question 32

What are the adaptations of smooth muscle tissue?

Answer 32

Many blood vessels Contains actin and myosin allowing the tissue to contract and propel substances

Question 33

What is the role of skeletal muscle tissue?

Answer 33

They are joined to bones by tendons. Allowing the bones to move

Question 34

What are the adaptations of skeletal muscle tissue?

Answer 34

It is able to rapidly modify rate of ATP synthesis and blood flow

Question 35

What is the role of the xylem tissue?

Answer 35

Transport water minerals

Question 36

What are the adaptations of xylem?

Answer 36

The walls are strengthened with a waterproof material called lignin

Question 37

What is the role of the phloem tissue?

Answer 37

Transport nutrients such as sucrose

Question 38

What is the role of guard cells in plants?

Answer 38

Form small openings called stomata which allows carbon dioxide, oxygen and water vapour in and out of the plant

Question 39

How are guard cells adapted to their role?

Answer 39

They can change shape to prevent excessive water loss They have thicker walls next to the stomata

Question 40

What is the role of the epidermis?

Answer 40

Allows carbon dioxide, oxygen and water vapour in and out of the plant

Question 41

How is epidermis adapted to its role?

Answer 41

Covered by a waxy waterproof cuticle to reduce water loss

Question 42

Which direction does the xylem transport material?

Answer 42

Upwards

Question 43

Which direction does the phloem transport material?

Answer 43

Upwards and downwards

Question 44

What are the sources of stem cells?

Answer 44

Embryonic Induced pluripotent Plant meristem Umbilical cord Adult