Aim: to Observe the Difference Between Onion Cells and Cheek Cells

Aim: To observe the difference between onion cells and cheek cells. Hypothesis: Variables: Equipment: Microscope 2 toothpicks Prepared slides Lamp Methylene blue Knife 2 glass slides solution Small piece of onion 2 cover slips Tweezers Petri dish

Method: ONION CELLS 1. . Take a glass slide and place a small drop of water in the centre. 2. Peel the onion and carefully pull a piece of the very thin membrane from between the layers. The teacher will demonstrate if necessary. 3. Place this in the drop of water on the slide and put on a coverslip. 4. Examine the onion under the microscope. Draw what you can see. 5. Repeat steps 1 to 4 but this time put a small drop of methylene blue in the water.

CHEEK CELLS AT ALL TIMES YOU ARE ONLY TO TOUCH YOUR OWN SLIDE AND TOOTHPICK NO ONE ELSE’S!! 1. Place a very small drop of methylene 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. Draw what you see 7. The slide is to be placed into the disinfectant BY YOU NOT YOUR PARTNER.

PREPARED SILDES 1. . From the prepared slides available choose one from a plant and one from an animal. Draw a cell from each slide.

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? Use a Venn Diagram. 2. Suggest why onion cells are different from cheek cells. 3. What is the purpose of the methylene blue? 4. Do all stains highlight the same parts of a cell? 5. How do the prepared slides compare to the fresh slide? 6. What are the differences between a light microscope and an electron microscope?

Conclusion: Total Score Above Level At level Below Level Well Below Level . Presents a clear opening to the report. . Introduction more like a . Does not give any information . The purpose of the experiment is . Gives very little information summary. about what to expect in the report. clearly identified and stated. . The purpose of the experiment is Introduction . The purpose of the experiment is . The purpose of the experiment is Some background to the not clear. identified. incorrect or not relevant. experiment is presented, why it is being done..

. The aim is clear and is linked to . Aim not stated or relevant to . The aim is clear. . Aim is not clear. Aim , the hypothesis. experiment. . Hypothesis and aim are linked, . Hypothesis is not directly linked . Hypothesis is based on ain and is . Hypothesis not stated or not Hypothesis hypothesis is clear. to aim. reasonable and fully explained. linked to aim.

. All variables, constants and . All variables, constants and . Most variables, constants and Variables, controls listed and explained . Few or none listed. controls listed. controls listed. . Good understanding of these and . No understanding of these Constants and . Understanding of these . Some understanding of these how they are related demonstrated. Controls demonstrated. demonstrated. demonstrated

. All materials and the setup used . All materials and the setup used in the experiment are clearly and in the experiment are clearly . Most of the materials are listed. . Many materials are not listed Materials/Setup accurately described listed. /explained/drawn. . Presents clear and easy-to-follow . Presents clear steps which are . Some of the steps are missing, . Most steps are missing and/or are steps which are logical and logical with some details Method confusing and/or lack detail. confusing. detailed. included. . Tables and/or graphs are . Tables and/or graphs are . Most tables and/or graphs are completed and are totally completed and accurate. complete. . Tables and/or graphs are missing. accurate & clearly labelled. . Most calculations have been . Some calculations have been . No or not all data are presented Data & Results . Calculations have been accurately accurately demonstrated and accurately demonstrated and . No calculations shown. demonstrated and significant significant figures have been significant figures have been figures have been addressed. addressed. partially addressed. . All questions are answered . Most questions are answered correctly and many other relevant correctly and a few other relevant Questions/ . All questions answered, some facts are included. Discussion facts are included. . Some or no questions answered. very briefly or incorrectly Discussion includes and expands on what . Discussion includes what was was learned from the experiment. learned from experiment

. Limitations to the experiment are . Limitations to the experiment are . Some limitations to the . Does not identify limitations to clearly identified and explained. identified. experiment are identified. Alterations and the experiment and does not make . Suggestions are made of how to . Some suggestions are made of . Some suggestions of changes of suggestions of how to make the Improvements make the results more accurate how to make the results more how to make the test more experiment more accurate or fair. and/or fair. accurate and/or fair. accurate or fair are made.

. Includes whether the results . Includes whether the results . No conclusion was included in . Makes little reference to aim and supported the hypothesis and supported the hypothesis, and the report OR shows little effort Conclusion hypothesis. links with aim. makes reference to aim. and reflection.

. All grammar and spelling are . Most grammar and spelling are Grammar, correct. . Several grammar and/or spelling . There are very frequent grammar correct. Spelling. . Lab report is neatly presented and errors are evident. and/or spelling errors. . Lab report is well-presented and uses accurate headings and . Lab report is neat, but the . Lab report is messy and Appearance & uses headings and subheadings to subheadings to visually organise material is not well organised. disorganised. visually organise the material. Organisation the material.