Independent variable in osmosis RPA
Concentration of sugar solution
Dependant variable in osmosis RPA
Change in mass of potato pieces
Control variable for osmosis RPA
Time left out for
Temperature and volume of solutions
Osmosis
The movement of water molecules from a more dilute region to a more concentrated region across a partially permeable membrane
What happens if the sugar solution has more water molecules than the potato piece?
The potato piece will increase in mass because it is more dilute inside and water molecules move across a partially permeable membrane into the potato piece
Why is the potato skin cut off?
It is a permeable membrane which does not let in the water molecules from
What happens to the mass of the potato when put in distilled water?
Its mass Increases
Higher water concentration on the outside
How to determine amount of water in the cells chloroplasts
When the line of best fit crosses the x-axis
Method for osmosis RPA
My method:
I -Cut 6 potato cylinders , with no skin. of the same size and length measured with ruler.
sucrose with distilled water
2 -Measure and record each potato cylinder’s mass using a top-par talarce.
3 - Put each potato piece into a boiling tube
4-Put I piece into a tube with 10cm3 of distilled water to compare to other solutions.
5- Put a different suger solution with a different concertation into each boiling tube
6- Put in the same place for up to 24 hours to remove excess
7- After, blot the potato pieces dry on a cloth and measure and record mass
8- Determine percentage change = change in mass/initial mass x 100
9- Repeat multiple times to idertiguinitial mass (g) aromalies and calculate a mean.
Amylase is a polymer of a smaller molecule called
Amino acids
An accurate set of results
Will have a mean close to the true value
A precise set of results
Is closely grouped together
Why do we use an LED for the light intensity pondweed RPA?
It releases less heat than a normal light bulb
What do we do in the pondweed RPA to measure the oxygen produced?
Using a funnel and measuring cylinder full of water upside down over the pondweed
Explain how amylase breaks down starch
Substrate binds to active site of amylase
Because shape of active site and substrate are complementary
A chemical reaction occurs to produce sugars
Word that describes a measurement in which there is a very little spread around the mean
Precise
What safety precautions should we take when doing the testing practical with Benedict’s reagent or iodine solution?
There is a risk of Benedict’s reagent/ iodine solution as an irritant so clean up spills immediately + wear gloves + wear eye protection
