stem cells

Question 1

an early stage embryo is a ball of cells made up of…

Answer 1

stem cells

Question 2

fertilisation is when…

Answer 2

a sperm cell joins with an ovum(egg cell)

Question 3

when the ovum is fertilised, what process does it go through to form the embryo?

Answer 3

the fertilised ovum undergoes mitosis and forms a ball of cells called an embryo

Question 4

what happens when the cells in an embryo become specialised?

Answer 4

they begin to form other specialised cells such as nerve cells and muscle cells

Question 5

what is the process where cells begin to specialise called?

Answer 5

cell differentiation

Question 6

over time, what do all of these cells come to form?

Answer 6

the adult organism

Question 7

are cells in an early embryo differentiated or not?

Answer 7

no they have not differentiated. Any cell is capable of differentiating into any type of body cell

Question 8

what is the definition of a stem cell?

Answer 8

a stem cell is an undifferentiated cell which can give rise to more cells of the same type and can differentiate to form other types of cells

Question 9

where else can we find stem cells besides an embryo?

Answer 9

they can be found in adult organisms such as the bone marrow.

Question 10

unlike embryonic stem cells, what can’t adult stem cells do?

Answer 10

unlike embryonic stem cells, adult stem cells can not differentiate into any other type of cell

Question 11

why can’t stem cells in bone marrow differentiate to any type of cell?

Answer 11

because stem cells found in bone marrow are adult stem cells, they can only differentiate to limited specialised cells such as cells found in our blood

Question 12

how are stem cells useful in medicine? (bone marrow)

Answer 12

•Bone marrow transplants - leukaemia is a cancer of the bone marrow,
to treat this,
first the patients existing bone marrow is destroyed using radiation
the patient then receives a transplant of bone marrow from a donor
the stem cells in the bone marrow now divide and form new bone marrow. They also differentiate and form blood cells

Question 13

what’s a problem when transferring stem cells in a bone marrow transplant?

Answer 13

• the donor has to be compatible with the patient. Otherwise the white blood cells produced by the donated bone marrow could attack the patients body
• There is a risk that viruses can be passed from the donor to the patient

Question 14

how can stem cells be useful in medicine? (therapeutic cloning)

Answer 14

• In therapeutic cloning, an embryo is produced with the same genes as the patient.
• which means that stem cells from the embryo can be transplanted into the patient without being rejected by the patients immune system.
• once inside the patient, the stem cells can then differentiate to replace cells which have stopped working correctly

Question 15

what can therapeutic cloning be used for?

Answer 15

This technique can be used for a range of medical conditions such as diabetes or paralysis.

Question 16

why might some people reject therapeutic cloning?

Answer 16

some people have ethical or religious objections to this procedure.

Question 17

what can meristem tissue do?

Answer 17

these stem cells can differentiate into any type of plant tissue, at any point in the life of the plant

Question 18

where are plant stem cells located?

Answer 18

in the meristems of plants

Question 19

at which life stage does plant differentiation occur?

Answer 19

plant cells keep the ability to differentiate throughout all life stages of the plant

Question 20

how can we stop a plant from going extinct

Answer 20

we could clone a rare plant or produce cloned crop plants for farmers

Question 21

what can we use to clone plant cells really quickly and cheaply?

Answer 21

we can use meristem tissue to produce clones of the plant quickly and cheaply

Question 22

some plant tissues contain stem cells

give the name of the tissue where plant stem cells are found

Answer 22

meristem

Question 22

give 2 places where meristem tissue can be found

Answer 22

at the tip of the roots
tip of shoots
in the buds and nodes of stems

Question 23

plant stem cells ( found in the meristem) can be used to clone plants , give 2 reasons why we would want to clone plants

Answer 23

rare plant species are cloned to be saved from extinction

plants with desirable features (eg disease resistance) can be produced in large numbers