Cell Biology - Cell differentiation and specialisation 22-25

Question 1

what is differentiation

Answer 1

the process by which a cell changes to become specialised for its job

Question 2

when does most cell differentiation occur
3 points

Answer 2

1) as an organism develops
2) in most animal cells the ability to differentiate is lost at an early stage after they become specialised
3) lots of plant cells don’t ever lose the ability

Question 3

what are cells that differentiate in mature animals mainly used for

Answer 3

repairing and replacing cells such as skin and blood

Question 4

what are undifferentiated cells called

Answer 4

stem cells

Question 5

give examples of specialised cells
5 points

Answer 5

1) sperm - reproduction
2) nerve - rapid signalling
3) muscle - contraction
4) root hair - absorbing water and minerals
5) phloem and xylem - transporting substances

Question 6

describe how sperm cell are specialised to reproduction
3 points

Answer 6

1) long tail and streamlined head - help it swim to the egg
2) a lot of mitochondria - to provide it with energy
3) enzymes in its head - to digest through the egg cell membrane

Question 7

what is the function of nerve cells

Answer 7

to carry electric signals from one part of the body to another

Question 8

how are nerve cells specialised for rapid signalling
2 points

Answer 8

1) long - to cover more distance
2) branched connections at their ends - to connect to other nerve cells and form a network throughout the body

Question 9

how are muscle cells specialised for contraction
2 points

Answer 9

1) long - has space to contract
2) lots of mitochondria - to generate energy needed

Question 10

how are root hair cells specialised for absorbing water and minerals
3 points

Answer 10

1) cells on surface of plant roots which grow into long ‘hairs’ that stick out into the soil
2) gives big surface area for absorption
3) don’t have chloroplasts - don’t photosynthesise

Question 11

how are phloem and xylem cells specialised for transporting substances
3 points

Answer 11

1) the cells are long and join end to end to form tubes
2) xylem cells are hollow in the centre - so stuff can flow through
3) phloem cells have very few subcellular structures - so stuff can flow through

Question 12

what can stem cells do
2 points

Answer 12

1) replication - they can produce more undifferentiated cells
2) differentiation - they can differentiate into different types of cell

Question 13

where are stem cells found
3 points

Answer 13

1) in early human embryos - embryonic stem cells
2) bone marrow - adult stem cells
3) meristems - plant stem cells

Question 14

what’s the difference between embryonic stem cells and adult stem cells
2 points

Answer 14

1) embryonic can have the potential to turn into any type of cell
2) adult can only turn into certain types such as blood cells

Question 15

how might stem cells be able to cure diseases
3 points

Answer 15

1) stem cells transferred from bone marrow of healthy person can replace faulty blood cells in a patient
2) embryonic can be used to replace faulty cells in patients - e.g. insulin producing cells for diabetes, nerve cells for paralysis
3) therapeutic cloning

Question 16

what is therapeutic cloning
3 points

Answer 16

1) a type of cloning where an embryo could be made to have the same genetic information as the patient
2) the stem cells produced from it would also have the same genes
3) so wouldn’t be rejected by the patient’s body

Question 17

what are the risks involved in using stem cells in medicine

Answer 17

stem cells grown in the lab may become contaminated with a virus that could be passed on to the patient

Question 18

why are some people for and against stem cell research
5 points

Answer 18

1) they think embryos shouldn’t be used in experiments as each one is a potential human life
2) they think scientists should focus on finding other sources of stem cells
3) others think curing a patient that already exists is more important than the rights of embryos
4) they argue that the embryos used in research are unwanted ones and would of been destroyed anyway
5) stem cell research is banned in some countries, not the UK

Question 19

when can plant stem cells differentiate

Answer 19

throughout the plants entire life they can differentiate into any type of plant cell

Question 20

what are the uses of plant stem cells
3 points

Answer 20

1) used to produce clones of whole plants quickly cheaply
2) used to grown more plants of rare species
3) to grow crops of identical plants that have desired features for farmers, e.g. disease resistant