cell structure and microscopy

Question 1

why will there be a faster rate of plasmid replication n a culture of high conc of amino acids? (2)

Answer 1

-amino acids used in protein synthesis
-so more enzymes for replication

Question 2

describe how a sample of chloroplasts can be isolated from the leaves. (4)

Answer 2

-break open cell and filter
-add to cold, buffered, isotonic solution
-centrifuge and remove nuclei
-spin at higher speed and remove chloroplast

Question 3

outline the role of organelles in the production, transport and release of proteins from eukaryotic cells. (4)

Answer 3

-DNA in the nucleus codes for proteins
-ribosomes produce proteins
- mitochondria makes ATP for protein synthesis
- golgi body modifies proteins

Question 4

give two advantages of TEM microscopes compared to SEM (2)

Answer 4

-higher resolution
-view internal structures

Question 5

contrast how an electron microscope and light microscope works (2)

Answer 5

uses electrons|uses light
higher resolution so can see smaller organelles |lower resolution

Question 6

contrast an electron microscope with a light microscope (3)

Answer 6

dead specimens|live specimens
black and white|colour
electron needs thinner specimens

Question 7

how can you prepare to observe starch grains in a plant cell using a light microscope? (4)

Answer 7

• add drop of water to slide
  -obtain thin section and place on water drop
• add iodine in potassium iodide
  -low cover slip using mounted needle