Explaining the effect of temperature on the rate of cellular respiration | Combined science

Starter quiz

What kind of cellular respiration is used to produce alcoholic drinks?

aerobic cellular respiration in animal cells

anaerobic cellular respiration in animal cells

anaerobic cellular respiration in yeast cells ✓

aerobic cellular respiration in yeast cells
Bacteria that produce lactic acid when they respire are used in the production of yogurt from milk. What can you conclude about the amount of oxygen dissolved in milk?

There must be lots of oxygen dissolved in milk.

There must be some oxygen dissolved in milk.

There must be very little oxygen dissolved in milk. ✓
The simple respirometer shown in the diagram is used to investigate the effect of temperature on the rate of cellular respiration. Match each variable to its correct example.

dependent variable

⇔

the distance moved by the coloured water ✓

independent variable

⇔

the temperature of the water bath ✓

control variable

⇔

the number of germinating peas ✓
When using this type of respirometer, the water moves up the capillary tube because the pressure inside the test tube falls. Why does the pressure in the tube fall?

Oxygen is used and the carbon dioxide produced is absorbed by the soda lime. ✓

Carbon dioxide is used and the oxygen produced is absorbed by the soda lime.

Soda lime absorbs oxygen before it can be used in respiration.

Soda lime absorbs carbon dioxide before it can be used in respiration.
A student plans to use a respirometer to investigate the effect of temperature and amount of glucose on the rate of respiration. The investigation will not produce valid results. Why?

Neither of the two dependent variables will affect the rate of respiration.

The two dependent variables will both affect the rate of respiration.

Neither of the two independent variables will affect the rate of respiration.

The two independent variables will both affect the rate of respiration. ✓
A student used the respirometer shown. After 5 minutes at 25 °C, the coloured water moved 8 mm towards tube A and 2 mm towards tube B. How many mm has the water moved because of cellular respiration?

6 mm ✓

8 mm

10 mm

16 mm

Exit quiz

The respirometer shown is used to measure the rate of respiration. What units would the rate of respiration be measured in?

°C/minute

cm $^3$ /minute

seconds/minute

mm/minute ✓
The following table shows results from a respirometer experiment. What conclusion can be drawn from these results?

As the temperature increases, the rate of cellular respiration decreases.

As the temperature increases, the rate of cellular respiration increases. ✓

As the temperature increases, the rate of cellular respiration stays the same.
The following table shows results from a respirometer experiment. Which statement about the data is true?

The rate triples for every 10 °C rise in temperature.

The rate doubles for every 10 °C rise in temperature. ✓

The increase in rate is linear.

The rate increases by 0.5 mm/min every 10 °C.
Enzymes work as catalysts because the substrate precisely fits into part of the enzyme molecule called the active site. Scientists use the ______ and key model to describe this precise fit.

'lock' ✓
Which of these is the best explanation of why the rate of cellular respiration increases with temperature?

Molecules move faster.

Molecules have more effective collisions.

Substrate molecules and enzyme molecules have more energy.

Substrate molecules and enzyme active sites collide more often. ✓
At 55 °C, the temperature is so high that it breaks bonds in the enzyme molecule, changing its 3D shape. The enzyme is ______ and no longer works.

'denatured' ✓

Worksheet

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Lesson Details

Key learning points

Calculate the rate of respiration by dividing the distance moved up the capillary tube of a respirometer by the time.
Use appropriate units for the rate of cellular respiration.
Compare the rate of respiration in small organisms at different temperatures.
Describe trends in the data.
Use ideas about enzymes and rate of chemical reactions to explain the effect of temperature on the rate of respiration.

Common misconception

Not appreciating that increasing temperature up to the optimum has a different effect on rate than increasing temperature above the optimum.

The effects on rate of increasing temperature up to and beyond the optimum are explained.

Keywords

Rate - A measure of how much change occurs per unit of time.
Cellular respiration - An exothermic chemical process that transfers energy for life processes, using glucose as fuel.
Respirometer - Apparatus used to measure the rate of respiration in small organisms.
Enzyme - A biological catalyst.
Denature - When bonds in an enzyme molecule break and the molecule changes shape.