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9. (a) (i) Explain the importance of double-blind testing in scientific experimentation - Leaving Cert Biology - Question 9 - 2013
Question 9
9. (a) (i) Explain the importance of double-blind testing in scientific experimentation. (ii) How does a hypothesis differ from a theory? (b) Answer the following ... show full transcript
Worked Solution & Example Answer:9. (a) (i) Explain the importance of double-blind testing in scientific experimentation - Leaving Cert Biology - Question 9 - 2013
Step 1
Explain the importance of double-blind testing in scientific experimentation.
Answer
Double-blind testing is important in scientific experimentation because it helps to eliminate bias. In this method, neither the participants nor the experimenters know who is receiving a particular treatment. This is crucial for ensuring that the results are not influenced by participants' or researchers' expectations, which can skew the outcomes.
Step 2
How does a hypothesis differ from a theory?
Answer
A hypothesis is a specific, testable prediction about the relationship between variables, while a theory is a well-substantiated explanation of some aspect of the natural world that is based on a body of evidence. A hypothesis may become a theory after rigorous testing and validation over time.
Step 3
When investigating the effect of either carbon dioxide concentration or light intensity on the rate of photosynthesis: How did you vary your chosen factor?
Answer
I varied the carbon dioxide concentration by changing the amount of sodium bicarbonate (NaHCO3) added to the solution, which directly affects the availability of CO2 for photosynthesis. Alternatively, if investigating light intensity, I adjusted the distance of the lamp from the plant or varied the wattage of the lamp used.
Step 4
When investigating the effect of either carbon dioxide concentration or light intensity on the rate of photosynthesis: Using suitably labelled axes, draw a graph of the results that you obtained.
Answer
The graph should include the rate of photosynthesis (measured in oxygen production or some other suitable metric) on the y-axis and the varying concentration of carbon dioxide or light intensity on the x-axis. It should clearly show the relationship between the independent and dependent variables, with a title indicating the experiment's focus.
Step 5
When demonstrating osmosis: For what purpose did you use Visking tubing, potato tissue or some similar material?
Answer
Visking tubing was used because it acts as a selectively permeable membrane, allowing the movement of water while restricting the passage of solutes. This setup effectively demonstrates the principles of osmosis.
Step 6
When demonstrating osmosis: At the end of the demonstration, how did you conclude that osmosis had occurred?
Answer
The conclusion that osmosis had occurred was indicated by a change in mass or volume of the Visking tubing or potato tissue. If the mass increased, it suggests water had entered the tubing or tissue, indicating that osmosis took place.
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Step 9
When investigating digestive activity during seed germination: How did you supply a substrate suitable for the digestive enzymes?
Answer
I supplied a suitable substrate for the digestive enzymes by using starch agar or milk agar in the experimental setup, which provided the necessary medium for enzymatic activity to be observed.
Step 10
When investigating digestive activity during seed germination: How did you ensure that no digestive enzymes were available on the control plate?
Answer
I ensured that no digestive enzymes were present on the control plate by using boiled seeds, which inactivate the enzymes. This control allows for a comparison against the experimental group, highlighting the effects of enzyme activity.