DCP:
Introduction:
In this experiment, Onion cells (Allium cepa) Cheek cells (Homo sapiens) were measured and compared. The aim of this experiment is to find out how both cells differ by comparing their size. Onion cells (Allium cepa) is plant cell and Cheek cells (Homo sapiens) is an animal cell.
Hypothesis:
The size of an animal cell (Homo sapiens) should be smaller than a plant cell (Allium cepa). Because a plant cell has cell wall which is to maintain the size of it while animal cell doesn’t. Also, plant cell usually has a large vacuole and chloroplast, therefore it should be larger than an animal cell. The estimate size of plant cell is between 300µm too 500µm1, animal cell should be around 1-100µm 2.
Method:
1. Measuring the ratio of the microscope
First, set up a microscope on the 40x objective and focus it on the ‘small ruler’. Then, adjusted the microscope stage till the ‘small ruler’ touches the left and the right-most point. Record it can calculate the ratio.
2. Preparing the slides of cells
Peel a piece of onion then place it on a eye piece. Add one drop of iodine solution then place a cover slip on top of it. Use a Q- tip to collect cheek cell from your cheek. Rub it against the eye piece, add a drop of methylene blue then cover it with a cover slip. Make sure that there’s no air bubble in it.
3. Find the size of each cell
Measure the length of 20 onion cells and 20 cheek cells on the 40x objective. Estimate the size of the cell by fitting them into the ruler from your eye piece.
Apparatus:
- Microscope (x40)
- Eye piece
- Onion
- Microscope slide x2
- Cover slip x2
- Forceps
Magnification:
100 division = 1µm
1 division = 10µm
±0.5 mm
Result:
Measured length of Onion cell and Cheek cell
Measured length of Onion cell /µm (±10) Measured length of cheek cell /µm
(±10)
500 70
500 60
250 50
370 40
270 60
290 50
500 30
460 40
280 20
360 70
500 50