Extraction of DNA from
Onion
MYP 5 – Grade 9
Class:
Start Date:
Due Date:
Subject: BIOLOGY
Name of Student:
Sec:
Acknowledgement of
assessment question
Acknowledgement of
assessment results
Student’s Signature
(Date)
Teacher’s Signature
(Date)
Criterion
Result
C: Processing and Evaluating (Max 8)
Criterion C: Processing and evaluating
Maximum: 8
At the end of year 5, students should be able to:
i. Present collected and transformed data
ii. Interpret
data and explain results using scientific reasoning
iii. Evaluate
the validity of a hypothesis based on the outcome of the scientific investigation
iv. Evaluate
the validity of the method
v. explain
improvements or extensions to the method.
Achievement level
0
Level descriptor
The student does not reach a standard described by any of the
descriptors below.
The student is able to:
1-2
3-4
5-6
i. collect and present data in numerical and/or visual forms
ii. interpret data
iii. state the validity of a hypothesis based on the outcome of a
scientific investigation
iv. state the validity of the method based on the outcome of a scientific
investigation
v. state improvements or extensions to the method.
The student is able to:
i. correctly collect and present data in numerical and/or visual forms
ii. accurately interpret data and explain results
iii. outline the validity of a hypothesis based on the outcome of a
scientific investigation
iv. outline the validity of the method based on the outcome of a
scientific investigation
v. outline improvements or extensions to the method that would
benefit the scientific investigation.
The student is able to:
i. correctly collect, organize and present data in numerical and/or
visual forms
ii. accurately interpret data and explain results using scientific
reasoning
iii. discuss the validity of a hypothesis based on the outcome of a
scientific investigation
iv. discuss the validity of the method based on the outcome of a
scientific investigation
v. describe improvements or extensions to the method that would
benefit the scientific investigation.
The student is able to:
7-8
i. correctly collect, organize, transform and present data in
numerical and/ or visual forms
ii. accurately interpret data and explain results using correct
scientific reasoning
iii. evaluate the validity of a hypothesis based on the outcome of a
scientific investigation
iv. evaluate the validity of the method based on the outcome of a
scientific investigation
v. explain improvements or extensions to the method that would
benefit the scientific investigation.
Command Terms:
Present: Offer for display, observation, examination or consideration
Describe: to give a detailed account or picture of a situation, event, pattern or process.
Discuss: Offer a considered and balanced review that includes a range of arguments, factors or
hypotheses. Opinions or conclusions should be presented clearly and supported by appropriate
evidence.
Evaluate: Make an appraisal by weighing up the strengths and limitations
Explain: give a detailed account.
Outline: Give a brief account.
State: Give a specific name, value or other brief answer without explanation or calculation.
Interpret: Use knowledge and understanding to recognize trends and draw conclusions from
given information
Achievement
level
Descriptor
EXTRACTION OF DNA FROM ONION
AIM:
To extract deoxyribonucleic acid (DNA) from Onion
BACKGROUND INFORMATION:
DNA is the genetic material of all living organisms. Within this master molecule, all the
information necessary to create and direct the chemical machinery of life is found. Before being
able to study DNA in the context of a university research laboratory, of medical analyses or of
criminal investigations, scientists must be able to extract it from the tissue in which it is contained.
MATERIALS NEEDED:
•An onion
•100 ml dishwashing liquid (0.01 ml / ml water)
• 50 ml 95 % ethanol
• Salt
• Cheesecloth
• Glass stirring rod
• 250 ml beaker-2, 500 ml beakers-1
• Blender
• Cutter
• Petri dishes
• Match box
• Tripod stand, gauze
• Spirit lamp
STEPS OF THE EXPERIMENT:
1. Take an onion, peel it and chop into small pieces
2. Take about 30ml water in a beaker
3. Add one teaspoon of salt in the beaker and stir
4. Add 2 teaspoons of washing liquid to the solution and stir well avoiding bubble formation
5. Put the chopped onions in the blender
6. Also add the solution in the beaker to the blender
7. Blend them for about 1 or 2 min to get a smooth mixture
8. Pour the mixture from the blender into a beaker
9. Heat the mixture for about 1-2 min, stirring it from time to time
10. Put the cheese cloth and filter the mixture.
11. Take 5ml of ethanol in a petri dish
12. Pour the filtrate gently into ethanol
13. Observe the DNA strands appearing in the ethanol.
RESULTS:
Construct a suitable table to show your results with a picture at each stage of your
work.
CONCLUSIONS:
Interpret your data and explain your results. Discuss the validity of your hypothesis.
•What do you see?
• Where is the DNA located in a tissue and in a eukaryotic cell?
• What is the composition of DNA?
• What is the composition of a cell membrane?
•Why was it necessary to chop the onion and mix it with a solution of washing liquid?
• What happens to the soap during the extraction of DNA from the onion?
•Why use 95% ethanol?
EVALUATION:
Evaluate the validity of the method and suggest improvements or extensions that
could be made