b2

Question 1

what does the nucleus of a cell contain

Answer 1

chromosomes made of DNA molecules. Each chromosome carries a large number of genes. in the body chromosomes are normally found in pairs

Question 2

describe the three stages of mitosis

Answer 2

1. DNA/chromosomes replicate. mitochondria and ribosomes (subcellular structures) increase in number
2. one set of chromosomes is pulled / moved to each end of the cell
3. the cytoplasm and cell membrane divides to form two identicle daughter cells

Question 3

why is mitosis important

Answer 3

for the growth and development of multicellular organisms.

Question 4

what is a stem cell

Answer 4

an undifferentiated cell that has the ability divide and form more of the same type of cell or differentiate into another tpe of cell

Question 5

embryonic stem cell

Answer 5

can be cloned and made to differentiate into most different types of human cells

Question 6

adult stem cell

Answer 6

can only differentiate into certain kind of cells - eg adult bone marrow can only differentiate into blood cells

Question 7

meristem in plants

Answer 7

can differentiate into any type of plant cell, throughout the life of the plant

Question 8

what can stem cells be used to treat

Answer 8

diabetes and paralysis

Question 9

embryonic vs adult stem cells

Answer 9

embryonic can differentiate into any, adult only a few types of cells
adult stem cells extraction is a painful process but embryonic is not
embryonic however has the potential to develop into life and with adult stem cells you can get consent.
there is also a risk with the transfer of viral infections with the use of stem cells

Question 10

theraputic cloning

Answer 10

• an embryo is produced with the same genes as
  the patient.
• stem cells from the embryo are not rejected by the patient’s
  body so they may be used for medical treatment
• a skin cell from the patient has its nucleus removed and put into an egg cell which then develops into an embryo. these can be collected and cultured

Question 11

benefits of meristem

Answer 11

Rare species can be cloned to protect from extinction.
Crop plants with special features such as disease resistance can be cloned to produce large numbers of identical plants for farmers.

Question 12

benefits of meristem

Answer 12

Rare species can be cloned to protect from extinction.
Crop plants with special features such as disease resistance can be cloned to produce large numbers of identical plants for farmers.