Photosynthesis and respiration
Warming up anaerobic respiration in yeast
Does temperature change how fast yeast releases carbon dioxide?
Watch first
Watch a leaf turn light, water and carbon dioxide into sugar.
What you need
Tick each one as you find it — 0 of 6 ready.
Stay safe: Use warm tap water, never boiling.
Plan the fair test
- Change: Water temperature
- Measure: Height of froth in mm
- Keep the same: Amount of yeast, sugar and water, and how much you stir
Objectives this evidences
- Understand aerobic and anaerobic respiration in living organisms, including the breakdown of organic molecules to enable all the other chemical processes necessary for life
Do it, one step at a time
Step 1 of 4
- Step 1. Put one teaspoon of yeast and one teaspoon of sugar in each glass.
- Step 2. Add 100 ml of cold water to the first, room-temperature water to the second and warm (not hot) water to the third.
- Step 3. Stir each once, then start the timer.
- Step 4. Measure the height of the froth in millimetres after 5, 10 and 15 minutes.
What should happen
The warm glass froths fastest: warmth speeds up respiration, and the gas is carbon dioxide.
Think about: Very hot water gives almost no froth. What has happened to the yeast's enzymes?
Write up your result
A sentence or two is enough to save it.
The lessons behind this practical
Each one opens with the same short film, and the film has a written transcript underneath if reading is easier than watching.
Now the quiz for this topic
Questions come from the lessons behind this practical, so nothing is asked that has not been taught.
Quiz
Photosynthesis and respiration quiz
4 questions from the lessons in this stage. No timer, and you can try again as many times as you like.