Practicals

Question 1

Examining onion cells

Answer 1

1) remove a small piece of the thin skin on the inside part of an onion.
2) add a drop of iodine to a microscope slide and place the small piece of skin on the drop on the slide.
3) place a coverslip onto the slide at a 45 degree angle, gently lower this onto the slide, avoid trapping bubbles
4) place the slide on the stage of a microscope and look through the eye piece lens, turning the focus wheel to obtain a clear image.
5) start using the lowest objective lens magnification to observe the slide and gradually the magnification of the objective lens.
6) once you found some cells draw a diagram.

Question 2

Investigating PH and enzyme activity

Answer 2

1) add 2cm cubed of amylase solution to five test tubes. Label tubes: PH 3,5,7,12
2) add 1cm cubed of the correct PH buffer to each test tube
3) leave for five minutes for the PH to affect the enzymes
4) add a drop of iodine to each well on a dropping tile
5) add 2cm cubed of starch to your PH3 test tube and immediately take a drop of the mixture and put it on your first well. The iodine will turn black showing starch is not broken down.
6) every 30 seconds take another drop and add it to the next well on the dropping tile
7) when the iodine no longer turns the black the starch has been broken down.
8) record the time taken for starch to breakdown
9) repeat 5-9 for each PH

Question 3

Investing osmosis in potato

Answer 3

1) add the same volume of 5 different sucrose solutions (0,20,40,60,80) into five different test tubes and label them with the correct concentration
2) use a cork borer to cut a potato into 5 cylinders of equal size and weigh them and record all the masses
3) place the cylinders into each test tube
4) after 40 minutes remove the potato pieces and dry off any excess sucrose.
5) reweigh the potato and record their new masses

Question 4

Drug development

Answer 4

First researchers target a disease and make lots of new drugs which could potentially e used to treat it.
The new drugs are tested on human cells and tissue to see if they’re toxic or do their job properly- many drugs fail at this stage.
The drugs that are left are tested on live animals to see if it’s toxic, does its job properly and to see what the right dosage should be.
Drugs which are safe are tested on healthy humans to see what side effects that they have.
Drugs which seem safe are tested on patients with the disease to see if it’s effective
Drugs are then licensed and produced