cells division and specialisation

Question 1

a genetic mutation stopped the metaphase checkpoint from working. suggest an abnormality the scientists might observe in the cells of this tissue.

Answer 1

cells contain an incorrect number of chromosomes because they havent lined up proper so when cell division occurs some will end up with lots of chromosomes whilst others have little

Question 2

a tissue had chromosomes that have been replicated despite containing damaged DNA. suggest which cell cycle checkpoint is no longer working.

Answer 2

G1 checkpoint
this is where DNA damage is checked

Question 3

suggest and explain another adaptation other than the flagella that are present in sperm cells.

Answer 3

acrosme –> contains digestive enzymes which break down the egg cell

Question 4

mitosis is involved in growth and repair of tissues. state two other roles

Answer 4

aesexual reproduction
proliferation of WBC

Question 5

explain why the type of nuclear division in a zygote is mitosis and not meiosis

Answer 5

mitosis is for the growth of the zygote
needs genetically identical cells

Question 6

explain how the organisation of homologus chromosomes during metaphase 1 increases genetic variation

Answer 6

independent assortment
homologus chromosomes line up at the centre of cell randomly and
each chromosome of a homologus pair is genetically different as it has a random combo of maternal and paternal chromosomes

Question 7

explain why Hydra sexually reproduce in the winter

Answer 7

winter = harsh conditions so sexual reproduction = more variation and some offspring can have useful alleles to survive

Question 8

describe how new xylem cells are produced

Answer 8

produced in the meristem
by differentiation and elongation

Question 9

describe the changes that occur inside stem cells as they differentiate to form erythrocytes

Answer 9

• nucleus is lost - more space to fit oxygen
• fill with Hb
• become biconcave - more flexible and increases surface area

Question 10

suggest 3 ways embryonic stem cells can be used in research

Answer 10

grown into different tissues, test for side effects
study to see how they develop into different cell types
test how effective they are in new medicinal drugs

Question 11

difference between an organ and a tissue

Answer 11

tissue- group of cells, for a specific role
organ- made of tissues - for a specific role

Question 12

explain the role of embryonic stem cells in the development of embryos

Answer 12

undifferentiated
can differentiate into any cell type

Question 13

explain why erythrocytes dont use the oxygen they transport

Answer 13

lack mitochondria
no aerobic respiration