Cell cycle/ cells

Question 1

During the root tip squash practical, why do you need to add hydrochloric acid?

Answer 1

breaks down middle lamella and allows cells to be separated
-also allows light to pass through

Question 2

Why do you add stain during root tip squash practical?

Answer 2

To make chromosomes visible
also so that stages of mitosis can be identified

Question 3

Explain how crossing over can produce gametes with new combinations of the alleles 2

Answer 3

-chromatids are produced with different combinations of alleles
-eg; aB

Question 4

Explain how independent assortment can produce gametes
with new combinations of the alleles 2

Answer 4

-Different combinations of chromosomes are produced
-so the alleles for 2 chromosomes could end up (be) in the same gamete as the other chromosomes.

Question 5

explain how crossing over may differ in sex chromosomes?

Answer 5

-crossovers cant form between some sections of the x and y chromosome
-because the y chromosome is shorter (they arent homologous chromosomes)

Question 6

Explain the role of the middle lamella when a plant cell completes mitosis. 2

Answer 6

it is produced between adjacent new cells (in cell plate)
because the middle lamella holds cell walls together

Question 7

Describe how the acrosome is involved in the digestion of the zona pellucida. 2

Answer 7

-the membrane of the acrosome fuses with the plasma membrane of the sperm cell
-releasing enzymes from the acrosome
-by exocytosis

Question 8

Describe the role of cell division in the production of monozygotic twins (when twins develop from a single fertilised egg cell) from a single fertilised egg cell. 2

Answer 8

-zygote divides by mitosis
-producing genetically identical cells

Question 9

polygenic inheritence

Answer 9

when multiple alleles are at multiple loci

Question 10

Why are double blind trials used

Answer 10

To compare effectiveness with placebo