1&2
Calculating
Magnification and
milli (10−3); micro (10−6); nano (10−9); pico (10−12)
Units
1mm = 1000 um
1cm = 10000 um
1mm = 1000000 nm
1um = 1000 nm
N.B. Magnification has no units as it is a ratio
1&2 Staining
Used to make organelles / chromosomes show up more
Focusing
place slide on stage & look through eyepiece lens
adjust to low power objective lens
Looking at Cells focus by turning focus knob (course then fine)
Increase magnification to mid-power objective lens
Microscopes Refocus
Continue to high power lens if required
Magnification
eyepiece lens (usually x10) x objective lens (often x4, x10 or
x40)
Core Practical e.g. 10 x 4 = x40 magnification
1&2 Reducing Sugar Test (Glucose)
Reagent: Benedict's reagent
Colour changes: Blue (negative) --> Brick red (positive)
Special conditions: HEAT Safety: Use a water bath
Protein Test
Food Tests Reagent: Biuret
Colour changes: Pale blue --> lilac (precipitate)
Starch Test
Reagent: Iodine
Colour changes: orange --> blue-black (DO NOT SAY PURPLE OR
BLUE)
Lipids (Fats) Test
Reagent: Ethanol then water
Core Practical Method: Add ethanol and shake, then settle, then pour top part of
solution onto water
Colour change: clear (water) --> cloudy
, Osmosis in Potatoes: Describe &
1&2 Explain the Graph Describe:
As the salt concentration increases the % mass change decreases although it is still a
positive change up to 0.3 mol dm3. The cells become tugid.
At 0.3mol dm3 salt solution there is no change in mass (equilibrium).
After 0.3 mol dm3 salt solution the % mass change continues to decrease with a
negative change. The cells become flaccid.
Explain:
From 0 - 0.3mol dm3 salt solution the water concentration in the cells of the potato
is less than the water concentration in the salt solution so water moves into the cells
due to osmosis from a high concentration of water to a lower concentration of water
through a partially permeable membrane.
At 0.3 mol dm3 salt solution the concentration of water inside and outside the
potato cells is the same, therefore there is no net movement of water.
Above 0.3 mol dm3 salt solution the water concentration in the cells of the potato is
more than the water concentration in the salt solution so water moves out of the
cells due to osmosis from a high concentration of water to a lower concentration of
Core Practical water through a partially permeable membrane.
1&2
Repeat using
intermediate concentrations / volumes /pH /temp etc.( use x-axis
Improving Practical to inform you of the independent variable)
Investigations Repeat each concentration and take an average of the results
Ignore outliers
1
1&2
age
sex
size
species
Control variables temperature
pH
volume
concentration
amount
Avoid this
word!
2
, Soda Lime
2
Respiration Rate Absorbs carbon dioxide
Bubble:
Moves along capillary tubing towards organism
Shows volume of oxygen taken up
Due to respiration
and energy requirements of organism
Control:
Set up same apparatus but with non-living replacement
Control Variables:
Temperature - could use a water bath to set to optimum for respiration
enzymes
Volume / size / age / species of living organism
Respiration rate calculation
Core Practical Rate = volume e.g. 3.8ml = 0.064 ml /second
time 60 s
Method:
1&2
pH and Enzyme put one drop of iodine solution into each dimple on the tile
Put amylase solution into a test tube
Add 1 cm3 of pH solution to the test tube
Activity Add starch solution to the mixture and start the stop clock.
After 20 seconds, take a small amount of the mixture in the pipette and
place one drop of it on the first iodine drop
pH 6 Results:
If the iodine goes blue-black then starch is still present. It has not been
pH 7 broken down by the enzyme.
If the iodine stays red there is no starch present, it has been broken down
by the enzyme.
The faster it does this the closer the pH to the optimum.
In the picture pH7 is closer to optimum than pH 6
Improvement:
Try intermediate pH 6.5
Core Practical
1
Treating damage and
disease in the brain
1
, 1
Patient injected with radioactive glucose
Radioactive atoms in the glucose cause gamma rays to be
produced
When the patient uses a certain part of their body, the cells
in the brain that control this become more active
PET scans More-active cells take in more glucose
So, more gamma rays come from the part of the brain
controlling the body
The greater concentration of gamma rays causes brighter
areas on the screen
1
CT scan PET scan
CT and PET scanning Shows structures in the brain
Shows activity in parts of the brain
yes yes
yes
Uses radioactivity yes
2
Scale has increased as human population has increased.
Resources required: antibiotics; food; oxygen
Fish farming - impact Positive impacts: sustainable - reduces overfishing in wild
on biodiversity Negative impacts: eutrophication
attraction of predators
escape of parasites
spread of diseases
escape of farmed fish
1
Calculating
Magnification and
milli (10−3); micro (10−6); nano (10−9); pico (10−12)
Units
1mm = 1000 um
1cm = 10000 um
1mm = 1000000 nm
1um = 1000 nm
N.B. Magnification has no units as it is a ratio
1&2 Staining
Used to make organelles / chromosomes show up more
Focusing
place slide on stage & look through eyepiece lens
adjust to low power objective lens
Looking at Cells focus by turning focus knob (course then fine)
Increase magnification to mid-power objective lens
Microscopes Refocus
Continue to high power lens if required
Magnification
eyepiece lens (usually x10) x objective lens (often x4, x10 or
x40)
Core Practical e.g. 10 x 4 = x40 magnification
1&2 Reducing Sugar Test (Glucose)
Reagent: Benedict's reagent
Colour changes: Blue (negative) --> Brick red (positive)
Special conditions: HEAT Safety: Use a water bath
Protein Test
Food Tests Reagent: Biuret
Colour changes: Pale blue --> lilac (precipitate)
Starch Test
Reagent: Iodine
Colour changes: orange --> blue-black (DO NOT SAY PURPLE OR
BLUE)
Lipids (Fats) Test
Reagent: Ethanol then water
Core Practical Method: Add ethanol and shake, then settle, then pour top part of
solution onto water
Colour change: clear (water) --> cloudy
, Osmosis in Potatoes: Describe &
1&2 Explain the Graph Describe:
As the salt concentration increases the % mass change decreases although it is still a
positive change up to 0.3 mol dm3. The cells become tugid.
At 0.3mol dm3 salt solution there is no change in mass (equilibrium).
After 0.3 mol dm3 salt solution the % mass change continues to decrease with a
negative change. The cells become flaccid.
Explain:
From 0 - 0.3mol dm3 salt solution the water concentration in the cells of the potato
is less than the water concentration in the salt solution so water moves into the cells
due to osmosis from a high concentration of water to a lower concentration of water
through a partially permeable membrane.
At 0.3 mol dm3 salt solution the concentration of water inside and outside the
potato cells is the same, therefore there is no net movement of water.
Above 0.3 mol dm3 salt solution the water concentration in the cells of the potato is
more than the water concentration in the salt solution so water moves out of the
cells due to osmosis from a high concentration of water to a lower concentration of
Core Practical water through a partially permeable membrane.
1&2
Repeat using
intermediate concentrations / volumes /pH /temp etc.( use x-axis
Improving Practical to inform you of the independent variable)
Investigations Repeat each concentration and take an average of the results
Ignore outliers
1
1&2
age
sex
size
species
Control variables temperature
pH
volume
concentration
amount
Avoid this
word!
2
, Soda Lime
2
Respiration Rate Absorbs carbon dioxide
Bubble:
Moves along capillary tubing towards organism
Shows volume of oxygen taken up
Due to respiration
and energy requirements of organism
Control:
Set up same apparatus but with non-living replacement
Control Variables:
Temperature - could use a water bath to set to optimum for respiration
enzymes
Volume / size / age / species of living organism
Respiration rate calculation
Core Practical Rate = volume e.g. 3.8ml = 0.064 ml /second
time 60 s
Method:
1&2
pH and Enzyme put one drop of iodine solution into each dimple on the tile
Put amylase solution into a test tube
Add 1 cm3 of pH solution to the test tube
Activity Add starch solution to the mixture and start the stop clock.
After 20 seconds, take a small amount of the mixture in the pipette and
place one drop of it on the first iodine drop
pH 6 Results:
If the iodine goes blue-black then starch is still present. It has not been
pH 7 broken down by the enzyme.
If the iodine stays red there is no starch present, it has been broken down
by the enzyme.
The faster it does this the closer the pH to the optimum.
In the picture pH7 is closer to optimum than pH 6
Improvement:
Try intermediate pH 6.5
Core Practical
1
Treating damage and
disease in the brain
1
, 1
Patient injected with radioactive glucose
Radioactive atoms in the glucose cause gamma rays to be
produced
When the patient uses a certain part of their body, the cells
in the brain that control this become more active
PET scans More-active cells take in more glucose
So, more gamma rays come from the part of the brain
controlling the body
The greater concentration of gamma rays causes brighter
areas on the screen
1
CT scan PET scan
CT and PET scanning Shows structures in the brain
Shows activity in parts of the brain
yes yes
yes
Uses radioactivity yes
2
Scale has increased as human population has increased.
Resources required: antibiotics; food; oxygen
Fish farming - impact Positive impacts: sustainable - reduces overfishing in wild
on biodiversity Negative impacts: eutrophication
attraction of predators
escape of parasites
spread of diseases
escape of farmed fish
1
