7. (a) State a use of each of the following in the biology laboratory - Leaving Cert Biology - Question 7 - 2019
Question 7
7. (a) State a use of each of the following in the biology laboratory.
(i) Biuret reagent (a solution containing copper sulfate and sodium hydroxide).
(ii) Benedict... show full transcript
Worked Solution & Example Answer:7. (a) State a use of each of the following in the biology laboratory - Leaving Cert Biology - Question 7 - 2019
Step 1
State a use of Biuret reagent (a solution containing copper sulfate and sodium hydroxide).
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Answer
The Biuret reagent is used to test for proteins in a sample. When proteins are present, the solution changes color, indicating a positive result.
Step 2
State a use of Benedict’s (or Fehlings) solution.
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Answer
Benedict’s solution is used to test for reducing sugars. When heated with a reducing sugar, the solution will change color, signaling a positive reaction.
Step 3
When preparing a sample of cheek cells on a microscope slide, why did you: Place a coverslip over the cells?
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A coverslip is placed over the cells to prevent them from drying out or to protect the objective lens from damage by liquid. It also helps to hold the samples in place and makes it easier to see them.
Step 4
When preparing a sample of cheek cells on a microscope slide, why did you: Apply methylene blue to the cells?
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Methylene blue is applied to stain the cheek cells, making them easier to visualize under the microscope.
Step 5
When extracting DNA from plant tissue, why did you use: Washing-up liquid?
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Washing-up liquid is used to break down the cell membrane, allowing for the release of DNA into the solution.
Step 6
When extracting DNA from plant tissue, why did you use: Freezer-cold ethanol?
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Freezer-cold ethanol is used to precipitate the DNA out of the solution, making it visible.
Step 7
When using seeds to investigate the effect of IAA on plant tissue, why did you: Carry out a serial dilution of an IAA solution?
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A serial dilution is conducted to create solutions of different concentrations of IAA, allowing for investigation of its effects on plant growth.
Step 8
When using seeds to investigate the effect of IAA on plant tissue, why did you: Place the seeds on a grid in Petri dishes?
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Seeds are placed on a grid in Petri dishes to facilitate the observation of root growth and to ensure that the seeds can be monitored accurately.
Step 9
When carrying out an activity to investigate osmosis: Why did you use Visking™ tubing?
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Visking™ tubing is used as a selectively permeable membrane to mimic the plasma membrane, allowing us to study osmosis effectively.
Step 10
When carrying out an activity to investigate osmosis: How did you know osmosis had taken place?
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Osmosis can be assessed by observing changes in the mass of the Visking tubing, indicating whether water has entered or exited the tubing. An increase in mass suggests water influx, while a decrease indicates water loss.
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