8. (a) Answer parts (i) and (ii) in relation to the scientific method - Leaving Cert Biology - Question 8 - 2010
Question 8
8.
(a) Answer parts (i) and (ii) in relation to the scientific method.
(i) What is a hypothesis?
(ii) Why is a control normally used when carrying out an expe... show full transcript
Worked Solution & Example Answer:8. (a) Answer parts (i) and (ii) in relation to the scientific method - Leaving Cert Biology - Question 8 - 2010
Step 1
What is a hypothesis?
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Answer
A hypothesis is an educated guess or possible explanation for a phenomenon. It acts as a tentative prediction that can be tested through experimentation.
Step 2
Why is a control normally used when carrying out an experiment?
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A control is used to provide a standard of comparison against the experimental group. It helps to isolate the effects of the variables being tested and ensures that the results are valid.
Step 3
Methylene blue or iodine solution when examining cells with the microscope.
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These solutions are used as stains to enhance the visibility of the cellular components under a microscope, making structures more apparent.
Step 4
An aquatic plant such as pondweed rather than a terrestrial plant when investigating the rate of photosynthesis.
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Aquatic plants can readily release oxygen bubbles, making it easier to measure the rate of photosynthesis compared to terrestrial plants.
Step 5
Washing-up liquid or other detergent while extracting DNA from plant tissue.
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Detergents help break down cell membranes, allowing access to the DNA within the cells.
Step 6
Freezer-cold ethanol while extracting DNA from plant tissue.
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Freezer-cold ethanol is used to precipitate DNA by separating it from the solution, making it visible for collection.
Step 7
Antiseptic wash solution in the investigation of the growth of leaf yeast on agar plates.
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The antiseptic wash helps prevent contamination in the experiment, ensuring that the growth observed is purely due to the yeast being tested.
Step 8
Biuret solution or alkaline copper sulphate in food testing.
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Biuret solution is used to test for soluble proteins, as it changes color in the presence of peptide bonds.
Step 9
Brown paper or Sudan III in food testing.
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Brown paper or Sudan III are used to test for fats or lipids, with Sudan III providing a color change indicating the presence of such substances.
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