New
New
Year 11
OCR
Higher

The effect of different substrates on cellular respiration in yeast: practical

I can investigate the effect of different substrates on cellular respiration in yeast by using a measuring cylinder to collect the gas produced.

New
New
Year 11
OCR
Higher

The effect of different substrates on cellular respiration in yeast: practical

I can investigate the effect of different substrates on cellular respiration in yeast by using a measuring cylinder to collect the gas produced.

Lesson details

Key learning points

  1. Living yeast cells immobilised in alginate beads will carry out cellular respiration and produce carbon dioxide gas.
  2. The gas can be collected and the volume of gas measured using an upturned measuring cylinder under water.
  3. Identifying independent and dependent variables, and variables to control to increase the validity of the results.
  4. How to read the volume of gas from the meniscus in the measuring cylinder after a set time.
  5. Collecting repeat measurements for each substrate, and collecting data for different substrates.

Common misconception

Pupils often read the volume of gas incorrectly as they do not measure it from the bottom of the meniscus of the water in the measuring cylinder.

This lesson contains a detailed explanation of how to correctly measure volumes from the meniscus, and why this is important.

Keywords

  • Cellular respiration - An exothermic chemical process that transfers energy for life processes, using glucose as fuel.

  • Independent variable - The factor that we change in an experiment.

  • Dependent variable - The factor that we measure in an experiment.

  • Random error - Causes results to differ by different amounts due to a factor other than the independent variable (the factor we changed).

  • Systematic error - Causes measurements to differ from the true value by the same amount each time they are taken.

In order to speed up the practical, you can divide the class in thirds and have one third conduct the experiment with glucose, one third with sucrose, and the final third with starch.
Teacher tip

Equipment

Conical flasks, glucose and two other carbohydrate substrates (e.g. sucrose and starch), yeast immobilised in alginate beads, bungs and delivery tubes, measuring cylinders, tank, water bath, timer.

Content guidance

  • Risk assessment required - equipment

Supervision

Adult supervision required

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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6 Questions

Q1.
Match the words to their meanings.
Correct Answer:Active site ,part of an enzyme to which a specific substrate can bind

part of an enzyme to which a specific substrate can bind

Correct Answer:Enzyme ,biological catalyst

biological catalyst

Correct Answer:Rate,how much change occurs per unit of time

how much change occurs per unit of time

Correct Answer:Lock and key ,a model used to explain the specificity of enzymes

a model used to explain the specificity of enzymes

Q2.
Which is the best explanation of the term denatured?
Bonds in the enzyme break, changing the shape of the enzyme.
Bonds in the substrate break, changing the shape of the active site.
Bonds in the substrate break, changing the shape of the substrate.
Correct answer: Bonds in the enzyme break, changing the shape of the active site.
Q3.
Some peas are boiled and then cooled back to room temperature. The peas are then used in a respirometer at 30°C. How will the respirometer results for the boiled peas compare to germinating peas?
An image in a quiz
The boiled peas will have a slower rate of cellular respiration.
The boiled peas will have a faster rate of cellular respiration.
The boiled and germinating peas will respire at the same rate.
Correct answer: The boiled peas will not respire but the germinating peas will respire.
Q4.
In three 5 minute tests using a respirometer, the water in the capillary tube moves 10 mm, 12 mm and 8 mm. The mean rate of respiration for these results is mm/min.
An image in a quiz
Correct Answer: 2, two
Q5.
What is oxygen debt?
The amount of oxygen needed for aerobic respiration.
The amount of oxygen needed for anaerobic respiration.
Correct answer: The amount of oxygen needed to remove lactic acid made by anaerobic respiration.
The amount of oxygen needed to remove CO$$_2$$ made by anaerobic respiration.
Q6.
For a working muscle cell, what is the major advantage of aerobic cellular respiration compared to anaerobic cellular respiration?
Correct answer: Aerobic cellular respiration transfers more energy per molecule of glucose.
Aerobic cellular respiration is faster.
Aerobic cellular respiration uses mitochondria.
Aerobic cellular respiration produces carbon dioxide.

6 Questions

Q1.
What name do scientist give to errors that cause measurements to differ from the true value by the same amount each time?
outlier
random error
Correct answer: systematic error
Q2.
Yeast is used in the production of a variety of food and drinks. Which food or drink is made without yeast?
Bread
Beer
Wine
Correct answer: Yogurt
Q3.
The equation for anaerobic respiration in yeast is not balanced. What coefficient (number) needs to be added before the formulae for ethanol and carbon dioxide, to balance the equation?
An image in a quiz
Correct Answer: 2, two
Q4.
Starch and cellulose are both large molecules made of thousands of glucose molecules joined together. The enzyme amylase can break down starch but not cellulose. Why?
The active site of amylase will bind to both starch and cellulose.
The active site of amylase will bind to neither starch nor cellulose.
Correct answer: The active site of amylase will bind to starch and not cellulose.
The active site of amylase will not bind to starch but will to cellulose.
Q5.
The apparatus is used to measure the rate of respiration in yeast, provided with different substrates. When using this apparatus, which of the listed variables is the independent variable?
An image in a quiz
Volume of water
Volume of gas collected in the measuring cylinder
Mass of substrate
Correct answer: Type of substrate
Mass of yeast
Q6.
To prevent random error, a meniscus must always be read the same way. Where on a meniscus are readings taken?
top
middle
Correct answer: bottom
top, middle and bottom then averaged

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