cells + division

Question 1

advantage of tem rather sem

Answer 1

allows internal structures within cells to be seen

Question 2

advantage of sem rather than tem

Answer 2

creates 3D images

Question 3

cell fractionation and ultracentrifugation

Answer 3

homogenise cells to break open cells
filter to remove cell debris
place into ice cold, isotonic, buffer solution
ice cold to reduce enzyme activity to reduce damage by enzymes, buffer solution to keep constant pH prevent enzymes denaturing
centrifuge at lowest speed, remove supernatant and place into next test tube
centrifuge at higher speed

Question 4

what synthesises proteins
what modifies protein
what does aerobic respiration

Answer 4

RER/ribosomes
golgi
mitochondria

Question 5

explain appearance of chromosome

Answer 5

two sister chromatids attached by a centromere, dna replication has occured

Question 6

why push hard downwards not sidewards (root tip squash)

Answer 6

to make thin layer of cells so light can pass through, downwards would cause cells to roll over each other, may break chromosomes

Question 7

how is anaphase shown?

Answer 7

two sister chromatids being pulled apart to opposite poles
centromeres of chromatids being pulled apart

Question 8

how do bacteria replicate

Answer 8

• by binary fission
• dna replicates
• cytoplasm divides

Question 9

explain what is occuring (CO)

Answer 9

crossing over has occured
between homologous chromosomes

Question 10

how to prepare root tip mount

Answer 10

place root in hydrochloric acid to halt cell division
stain root tip
macerate tissue with mounted needle
press down coverslip firmly