Aim: To observe the difference between onion cells and cheek cells.
Hypothesis:
Variables:
Equipment:
Microscope
Lamp
2 glass slides
2 cover slips
2 toothpicks
Methylene blue solution
Iodine solution
Knife
Small piece of onion
Petri dish
Tweezers
Method:
ONION CELLS
1. Cut and peel an onion to reveal the fine transparent ‘skin’ between the onion layers.
2. Lay a flat piece of the ‘skin on a glass slide. Be careful not to fold or scrunch it up.
3. Smooth out with the flat end of a toothpick.
4. Place a drop of iodine onto the onion.
5. Cover with a cover slip.
6. Focus under low then high power.
7. Draw what you see on both low and high power.
CHEEK CELLS
AT ALL TIMES YOU ARE ONLY TO TOUCH YOUR
OWN SLIDE AND TOOTHPICK NO ONE ELSE’S!!
1. Place a drop of methyl blue onto a glass slide.
2. Gently scrape the inside of your cheek with the blunt end of a toothpick.
3. Dab the scrapings into the methyl blue on the slide.
4. Place the toothpick in the rubbish bin (YOU NOT YOUR PARTNER)
5. Cover with a cover slip.
6. Focus under low then high power.
7. Draw what you see on both low and high power.
8. The slide is to be placed into the disinfectant BY YOU NOT YOUR PARTNER.
Results:
The drawings of the cells you have viewed under the microscope form your results
Discussion:
1. What are the similarities between the onion and cheek cells?
2. Suggest why onion cells are different from cheek cells.
3. What are the advantages of staining cells?
4. What are the disadvantages of staining cells?
5. Do all stains highlight the same parts of a cell?
6. What did you notice with methyl blue and iodine in terms of staining cell parts?
Conclusion:
Total Score / Above Level / At level / Below Level / Well Below LevelIntroduction / § Presents a clear opening to the report.
§ The purpose of the experiment is clearly identified and stated. Some background to the experiment is presented, why it is being done.. / § Introduction more like a summary.
§ The purpose of the experiment is identified. / § Gives very little information
§ The purpose of the experiment is not clear. / § Does not give any information about what to expect in the report.
§ The purpose of the experiment is incorrect or not relevant.
Aim , Hypothesis / § The aim is clear and is linked to the hypothesis.
§ Hypothesis is based on ain and is reasonable and fully explained. / § The aim is clear.
§ Hypothesis and aim are linked, hypothesis is clear. / § Aim is not clear.
§ Hypothesis is not directly linked to aim. / § Aim not stated or relevant to experiment.
§ Hypothesis not stated or not linked to aim.
Variables, Constants and Controls / § All variables, constants and controls listed and explained
§ Good understanding of these and how they are related demonstrated / § All variables, constants and controls listed.
§ Understanding of these demonstrated. / § Most variables, constants and controls listed.
§ Some understanding of these demonstrated. / § Few or none listed.
§ No understanding of these demonstrated.
Materials/Setup / § All materials and the setup used in the experiment are clearly and accurately described /explained/drawn. / § All materials and the setup used in the experiment are clearly listed. / § Most of the materials are listed. / § Many materials are not listed
Method / § Presents clear and easy-to-follow steps which are logical and detailed. / § Presents clear steps which are logical with some details included. / § Some of the steps are missing, confusing and/or lack detail. / § Most steps are missing and/or are confusing.
Data & Results / § Tables and/or graphs are completed and are totally accurate & clearly labelled.
§ Calculations have been accurately demonstrated and significant figures have been addressed. / § Tables and/or graphs are completed and accurate.
§ Most calculations have been accurately demonstrated and significant figures have been addressed. / § Most tables and/or graphs are complete.
§ Some calculations have been accurately demonstrated and significant figures have been partially addressed. / § Tables and/or graphs are missing.
§ No or not all data are presented
§ No calculations shown.
Questions/ Discussion / § All questions are answered correctly and many other relevant facts are included. Discussion includes and expands on what was learned from the experiment. / § Most questions are answered correctly and a few other relevant facts are included.
§ Discussion includes what was learned from experiment / § All questions answered, some very briefly or incorrectly / § Some or no questions answered.
Alterations and Improvements / § Limitations to the experiment are clearly identified and explained.
§ Suggestions are made of how to make the results more accurate and/or fair. / § Limitations to the experiment are identified.
§ Some suggestions are made of how to make the results more accurate and/or fair. / § Some limitations to the experiment are identified.
§ Some suggestions of changes of how to make the test more accurate or fair are made. / § Does not identify limitations to the experiment and does not make suggestions of how to make the experiment more accurate or fair.
Conclusion / § Includes whether the results supported the hypothesis and links with aim. / § Includes whether the results supported the hypothesis, and makes reference to aim. / § Makes little reference to aim and hypothesis. / § No conclusion was included in the report OR shows little effort and reflection.
Grammar, Spelling.
Appearance &
Organisation / § All grammar and spelling are correct.
§ Lab report is neatly presented and uses accurate headings and subheadings to visually organise the material. / § Most grammar and spelling are correct.
§ Lab report is well-presented and uses headings and subheadings to visually organise the material. / § Several grammar and/or spelling errors are evident.
§ Lab report is neat, but the material is not well organised. / § There are very frequent grammar and/or spelling errors.
§ Lab report is messy and disorganised.