B2- Cell division

Question 1

What do we find in the nucleus ?

Answer 1

-In the nucleus we find chromosomes , which are made of hte molecule DNA .

Question 2

How many chromosomes in a human ?

Answer 2

-Body cells contain two of each chromosome , they ar paired .
-Human body cells contain 23 pirs of chromosomes .
Chromosomes carry a large number of genes -determine our featrues .

Question 3

Cells have to e able to divide - process known as ?

Answer 3

Cell Cyle

Mitosis division

Question 4

What is the first stage of mitosis ?

Answer 4

Cell grows in size and mass and chromsoomes are replicated . (s1) INTERPHASE
-The nuclear membrane breaks down .9(s2) ALL MITOSIS
-Chromosomomes align acoss cenrer os cell .(s2)
One copy of each chromsome moves to opposite end of cell (s2)
nuclear ememrabne forms . (s2)
cell memrbane and cytoplasm divide (S3) CYTOKENSIS

Question 5

What is the second stage of mitosis ?

Answer 5

-One set of chromosomes is pulled to ehch end of the cell .

The nucleus also divides .

Question 6

What is the final stage of mitosis ?

Answer 6

-The cytoplasm and cell membrane divide to form tw identical cells .

Question 7

What is one function of mitosis ?

Answer 7

-Mitosis is essentia for growth and development of multicelluar orgaisms (plants and animlas ).

Question 8

What is the second function of mitosis ?

Answer 8

-Mmitosis takes place when an organism repairs itself (broken bone healing) .

Question 9

What is the third function of mitosis ?

Answer 9

Mitosis happens during asexual reporduction .

Question 10

Where can you specialise cells into anything in humans ?

Answer 10

When sperm and egg fuse during ferrtilisation , vum undergoes mitosis until ball of cells known as EMBRYO forms . Overtime , these cells undergo mitois and egin to form specialsied cells like nerve cells .

Question 11

What is differentiation?

Answer 11

when cells specialise .

Question 12

Early stage embryo ;

Answer 12

Have not differentaited . Any cell is capable oof differentating into ny tpe of body cell . Scientists call these EMBRYONIC STEM CELLS .

Question 13

What is a stem cell

Answer 13

A stem cell is an undfferentiateed cell which can give rise to more cells of the same type and cn differentaie to form other type of cells .

Question 14

Where can stem cells be found in an adult organism ?

Answer 14

Bone marrow , stem cells can differentaite to form cells found in our blood .

Question 15

Differrence between adult and embryonic sem cells ?

Answer 15

Unlike embryonic stem cells , adult cells can’t differentate into any other type of cell .

Question 16

Example of stem cells use in medicine .

Answer 16

• Bone marrow transport

- Leukaemia is a cancer o the bone marrow .

Question 17

FIrst stage of bone marrow Transplant -for Leukaemia

Answer 17

-To treat Leukaemia , the patients existing bone marow is destroyed using radiation .

Question 18

Second stage of bone marrow transplant

Answer 18

-The patiennt then receives a transplant of bone marrow from a doctor .

Question 19

Third stage of a bone marrow transplant .

Answer 19

-Stem cells in the bone marrow now divide to form new bone marrow . They can also differerntiate and form blood cells .

Question 20

Problem with bone marrow Transplants (1) .

Answer 20

-The donor has to be compatible with the patient . Otherwise white blood cells produced by the donte bone marrow could attack the pateints body .

Question 21

Problem with bone marrow transpalnts (2)

Answer 21

-There is a risk that viruses can be apssed from the donor to the pateint .

Question 22

Another way , stem cells can be used in medicne .

Answer 22

Therapeutic Cloning :

-Ane mebryo is produced with the same geens as the patient .

Question 23

Stage one of therapeutic cloning ;

Answer 23

-Stem cells from the embryo can be transplanted into a patient without being rejected by the patient’s immune sytem .

Question 24

Stage two of therapeutic cloning :

Answer 24

Once isnide the patient , the stem cells can differentiate , to replcase cells which have stopped working correctly .
This techinique can be used for diabaates or paralysis .
-However , some have ehtical and religious obections to this process .

Question 25

Use of stem cells in plants ?

Answer 25

-Roots and buds contain meristemtissue . These stem cells can differnetaite into any type of plant tissue at any point in the life of a plant .

Question 26

What can we use meristem tissue for ?

Answer 26

• To clone a rare plnt to stop it going extinct , or we could produce a cloned crop plant for farmers e,g disease resistant plants .
• RThis is quick and cheap

Question 27

problem with embryonic stem cells .

Answer 27

• come from aborted embryos , spare embros , donated as they not toehrwise be used . Some say the use of potentail human beign a source orf cells or cure to others ?
• As embryo cannot give permsssion , using ir is a violation of human rights .

Question 28

therapies mebryo problem

Answer 28

-expensive
diffiicult hard ot control .
Only been working for past 20 , difficult to persuade embryonic stem cells to differentiate into clels needed to reat pateints .
-viruses use bone marro stuff .
-money wasted on it , lot of investemnt can be used for other things .