1
Q
Give one way that an image produced by a LSC microscope differs from an electron microscope [1]
A
- lower res
- fluorescent tag
- movement
- diff layers
2
Q
Explain how to measure the diameter of the nucleus of one of the cells when observing thru a LIGHT microscope [4]
A
- use eyepiece graticule
- calibrate graticule, using stage micrometer (calc length of 1 epu)
- measure the diameter of nucleus in epu
- take repeat measurements & calc a mean diameter in epu
- multiply epu by calibration factor to calc diameter
3
Q
3 improvements to dry mount and explain why they increase validity [6]
A
- sharp blade (so slide is thin enough & individual cells are visible)
- wet mount (prevents dehydration/distortion of cells)
- squash slide (easier to see individual cells)
4
Q
Describe how the student could use the temporary mounts to determine the mean number of chloroplasts in the leaf cells [3]
A
- select large number of cells OR select cells at random
- count the total number of chloroplasts in those cells
- divide the number of chloroplasts by the number of cells counted
5
Q
What is the animal cell organelle that contains 70S ribosomes [1]
A
mitochondria
6
Q
Describe why ATP is the universal energy currency [3]
A
why it is universal: Used in all organisms
why it is energy: Releases energy in small quantities
why is it currency: coupled w/ energy requiring activities
7
Q
Describe the roles of the cytoskeleton [3]
A
- cell support
- movement of cilia/flagella
- changing cell shape eg muscle contraction
- organelle movement/holding in place
- movement of chromosomes
