topic 1

Question 1

using a light microscope

Answer 1

• place slide on stage and look through eyepiece lens
• turn focus wheel to get a clear image
• start with lowest objective lens magnification
• increase objective lens magnification and refocus

Question 2

equation for magnification

Answer 2

magnification = image/real

Question 3

order of units

Answer 3

mm
µm
nm
pm

milli, micro, nano, pico

Question 4

eukaryotic cells

Answer 4

plant and animal cells
•cell membrane
• cytoplasm
•nucleus, carrying dna
• membrane bound organelles

Question 5

prokaryotic cells

Answer 5

bacterial cells
• cell wall
•cell membrane
•flagella
•singular circular DNA strand + plasmid dna

Question 6

cell membrane

Answer 6

in plants and animals

controls what enters and leaves the cell

Question 7

cytoplasm

Answer 7

chemical/cellular reactions occur

has enzymes, organelles, dissolved ions and nutrients

Question 8

permanent vacuole

Answer 8

• contains cell sap and a solution of salts, sugars and organic acids
• found in cytoplasm
• improves cell turgidity/rigidity

Question 9

cell wall

Answer 9

plant (and bacteria) - made of cellulose, provides strength, prevents bursting of cell during osmosis

Question 10

light microscopes

Answer 10

observes dead and living
max 2000x magnification
max 200nm resolving power
can view tissues, cells and large cellular structures

Question 11

electron microscope

Answer 11

observes dead
electrons have a way smaller wavelength than light
up to 2,000,000x magnification

Question 12

testing for starch

Answer 12

add iodine

if starch is present it goes from orange-brown to a dark blue-black

Question 13

testing for lipids

Answer 13

shake with ethanol for about a minute until it dissolves and pour into water
if lipids are present they will precipitate and show up as a milky emulsion

Question 14

testing for proteins

Answer 14

use the biuret test
•first add a few drops of potassium hydroxide to make the solution alkaline
• add some copper(II) sulphate solution (bright blue)
• no protein - stays blue, yes protein - purple

Question 15

testing for reducing sugars

Answer 15

• add Benedicts reagent (blue) to a sample and heat in a 75˚C waterbath
• if positive, a coloured precipitate will form
• blue - brick red depending on concentration of reducing sugar