Lesson 3 of 5 · Cells
Experiment⭐ 30 XP🌿 Wild JungleWhy Cells Are Small
Why Cells Are Small.
🎯 Your mission
Set it up. Test it. Be amazed.
⚡ The twist
Every species solves the same problem differently.
Mind = Blown
🐙 An octopus has 9 brains and 3 hearts.
Make a hypothesis first
Before you watch: what do you think it'll do?
What You'll Learn
A cell must move materials in and waste out across its surface. As a cell grows, its volume rises faster than its surface area, so the surface eventually cannot serve the inside. That limit is why organisms grow by making more cells rather than bigger ones.
Key Words
Tap a word to see its definition.
Materials Needed
- potato
- knife
- food colouring
- ruler
- beaker
Safety First
- Cutting must be done by an adult, or with a blunt tool on a board.
- Food colouring stains — protect the surface and wash hands after.
Steps
Read the explanation above and note the two key terms before you start.
Cut agar or potato cubes of 1 cm, 2 cm and 3 cm, soak them in food colouring for the same time, then slice each and measure how far the colour reached as a fraction of the cube.
Record what actually happened, including anything that did not match what you expected.
Write a conclusion that answers the question this lesson opened with, and state your uncertainty.
Check Your Understanding
Question 1
1 of 2As a cell gets larger, its surface area to volume ratio:
Where you see this in real life
Your own body is doing this thousands of times every second.
Stretch Challenge
Try this in real life this week.
Find one thing about your body that's different from a friend's. Wonder why.
For the dinner table
“Tell me something you noticed about your own body today.”
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Why Cells Are Small
Set it up. Test it. Be amazed.
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