B2 Cell Division

Question 1

How many chromosomes do human body cells have

Answer 1

46

Question 2

How many chromosomes do gametes cells have

Answer 2

23

Question 3

Chromosomes

Answer 3

Coiled up lengths of DNA molecules

Question 4

Why are chromosomes normally found in pairs

Answer 4

Body cells have 2 copies of each chromosome one from organism’s mother and one from it’s father

Question 5

What do chromosomes contain

Answer 5

Large number of genes which control development of different characteristics

Question 6

Why do cells divide

Answer 6

To produce new cells

Question 7

Mitosis

Answer 7

The stage of the cell cycle when the cell divides

Question 8

What do multicellular organisms use mitosis for

Answer 8

To grow or replace cells that have been damaged

Question 9

3 steps of cell cycle

Answer 9

Growth

DNA replication

Mitosis

Question 10

What happens during growth and DNA replication

Answer 10

Cell grows and increases amount of subcellular structures such as mitochondria and ribosomes

It then duplicates DNA so there’s 1 copy for each new cell

DNA copied and forms X-shaped chromosome

Question 11

What happens during mitosis

Answer 11

Chromosome lines up at centre of cell

Cell fibres pull them apart

Chromosomes go opposite ends of cell

Nuceleus divides

Cytoplasm and cell membrane divode

Now have 2 new daughter cells with exact same DNA

Question 12

Why genetic material must be doubled during mitosis

Answer 12

It’s important that the daughter cells have a copy of every chromosome

Question 13

Describe a situation where mitosis is occurring

Answer 13

Replacing skin cells

Question 14

Gene

Answer 14

A section of DNA which controls part of a cell

Question 15

Gamete

Answer 15

A reproductive cell of an animal or plant

Question 16

Why mitosis is important for living organisms

Answer 16

Mitosis helps organisms grow in size and repair damages tissue

Question 17

Differentiation

Answer 17

Process when a cell changes to become specialised for its job

Question 18

What happens as cells change

Answer 18

They develop different subcellular structures and turn into different types of cells

This allows them to carry out specific functions

Question 19

When does differentiation occur

Answer 19

As organism develops

Question 20

In most animal cells when do animals lose their abilities to differentiate

Answer 20

Lost at an early stage

Question 21

What are differentiated cells in mature animals mainly used for

Answer 21

Repairing

Replacing cells

Question 22

Growth

Answer 22

An increase in total mass of a cell

Question 23

Examples of specialised cells

Answer 23

Sperm cells, nerve cells, phloem and xylem cells

Question 24

Function and adaptation of sperm cells

Answer 24

To get male DNA to the femal DNA

Long tail and streamlined head

Question 25

Function and adaptation of nerve cells

Answer 25

Carry electrical signals Are long and roundhead

Question 26

Function and adaptation of muscle cells

Answer 26

To contract quickly Contain lots of mitochondria, multiple nuclei

Question 27

Function and adaptation of root hair cells

Answer 27

Absorbs water from the soil by osmosis Large surface area increases rate of absorption, storage roots

Question 28

Function and adaptation of phloem cells

Answer 28

Moves food in plants Have few subcellular structures, sieve tubes

Question 29

Function and adaptation of xylem cells

Answer 29

Transports water in plants Hollow tube, strengthened by lignin

Question 30

Compare and contrast differentiation in plants and animals

Answer 30

Animals can differentiate in early stages of life Plants can differentiate throughout their whole life

Question 31

Why plant clones are genetically identical to each other

Answer 31

Clones contain identical sets of genetic material in the nucleus

Question 32

How using tissue culture creates a clone of a plant

Answer 32

Sample of tissue is extracted then separated Cells are cultured and grown with help of growth medium These cells replicate and can be divided again

Question 33

Explain why it is easier to clone a plant compared to an animal

Answer 33

Plants are totipotent, meaning they can differentiate into any type of cell Animal cells have more limited ability to differentiate

Question 34

How to clone a plant using apparatus correctly

Answer 34

A branch from the parent plant is cut off Its lower leaves are removed Stem is planted in damp compost

Question 35

Stem cell

Answer 35

A cell that is not differentiated

Question 36

Embryonic stem cell

Answer 36

A type of stem cell derived from early-stage embryo

Question 37

Adult stem cell

Answer 37

Type of stem cell found in various tissues of the body after development

Question 38

Differences between embryonic and adult stem cells

Answer 38

Embryonic cells found from embryos, adult cells found in various tissues Embryonic cell can differentiate into any type of cell and adult cells can't

Question 39

Advantages of adult stem cells

Answer 39

Less likely to cause immune rejection in treatments They don't involve destruction of embryos

Question 40

Disadvantages of adult stem cells

Answer 40

Harder to grow in laboratory Only differentiate to limited number of cells

Question 41

Advantages of embryonic stem cells

Answer 41

Can differentiate into any type of cell Can treat wide range of diseases

Question 42

Disadvantages of embryonic stem cells

Answer 42

Ethical concerns Risk of immune rejection

Question 43

Ethical concerns of embryonic stem cells

Answer 43

People believe destroying an embryo is equivalent to taking a human life People believe life starts at birth and an embryo is a life and so should be treated with as much respect as a fully developed human Embryo has potential to be human killing it

Question 44

Why embryonic stem cells are useful for treating medical conditions

Answer 44

They are very useful for treating diseases because of their ability to become any cell type and their potential to regenerate damaged tissues

Question 45

Why adult stem cells are useful for treating medical conditions

Answer 45

They are useful as they can differentiate into specific cell types related to the tissue or organ where they're found which is helpful for repairing and regenerating tissues

Question 46

Why are plant clones are produced in the agriculture industry

Answer 46

It allows a variety of a plant with desirable characteristics to be produced cheaply, quickly and on a large scale

Question 47

Ways that stem cells can be used to help medical conditions

Answer 47

Replace cells damaged by chemotherapy or disease Serves as a way for the donor's immune system to fight some types of cancer and blood-related diseases

Question 48

Use of stem cells

Answer 48

To treat conditions when bone marrow is damaged and no longer able to produce healthy blood cells

Question 49

How do prokaryotic cells replicate

Answer 49

Binary fission

Question 50

Therapuetic cloning Steps 1-4

Answer 50

Human egg taken from donor Remove egg nucleus Insert patients DNA Stimulate cell division

Question 51

Therapuetic cloning Steps 5-7

Answer 51

Develop blastocyst Extract stem cells Differentiate cells

Question 52

What therapeutic cloning can be used for

Answer 52

Studying diseases Diabetes treatment Organ repair