2.1

Question 1

Define resolution. (3)

Answer 1

(1) the MINIMUM distance apart…
(2) that 2 OBJECTS CAN BE…
(3) in order for them to appear as SEPARATE ITEMS.

Question 2

What is the equation used to find magnification? (1)

Answer 2

magnification = image size / object size

Question 3

How many mm is equivalent to 1 metre? (1)

Answer 3

. -3
10^

Question 4

How many um is equivalent to 1 metre? (1)

Answer 4

. -6
10^

Question 5

How many nm is equivalent to 1 metre? (1)

Answer 5

. -9
10^

Question 6

Define magnification. (1)

Answer 6

(1) how MANY TIMES BIGGER the image is COMPARED TO the actual object

Question 7

What is the resolution of a light microscope? (1)
What is the resolution of an electron microscope? (1)

Answer 7

(1) 0.2 um
(1) 0.1 nm

Question 8

What is cell fractionation? (2)

Answer 8

(1) the process by which CELLS are BROKEN UP…
(2) and the contents of the cells (ORGANELLES) are SEPARATED OUT

Question 9

What type of solution is the tissue placed in before cell fractionation begins? Explain each point. (6)

Answer 9

(1) BUFFERED —> (4) maintains a constant pH
(2) ISOTONIC —> (5) prevents ORGANELLES from shrinking or bursting from osmosis.
(3) COLD —> (6) reduces enzyme activity that may break down the organelles

Question 10

What are the 2 stages of cell fractionation? (2)

Answer 10

(1) homogenation
(2) ultracentrifugation

Question 11

Describe what happens in Homogenation (stage 1). Explain what each part leads to. (4)

Answer 11

(1) cells are BROKEN UP by a HOMOGENISER…
(2) this releases organelles from the cells.
(3) the HOMOGENATE (resultant fluid) is then FILTERED…
(4) to remove any complete cells or large debris

Question 12

Describe what happens in Ultracentrifugation (stage 2). (8)

Answer 12

(1) the tube of FILTRATE is placed in the ULTRACENTRIFUGE…
(2) and SPUN at a SLOW SPEED
(3) the HEAVIEST ORGANELLES are forced to the BOTTOM of the tube…
(4) so they form a THIN SEDIMENT / PELLET
(5) the fluid at the top (SUPERNATANT) is REMOVED and put in another tube..
(6) the tube is SPUN again but at a FASTER SPEED
(7) the next HEAVIEST organelle is FORCED to the BOTTOM of the tube.
(8) the process continues as the speed increases every time and the next heaviest organelle is sedimented.

Question 13

What is the order of the weight of the organelles from HEAVIEST to LIGHTEST (based on TB)? (4)

Answer 13

(1) nuclei —> (2) mitochondria —> (3) lysosomes —> (4) ribosomes