Cell Size and Function
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Objective
I can explain how cell size and surface area to volume ratio affect cell function.
Part 1 of 4
Warm-up video
Khan Academy · 8:56Vetted channel
We don't generate video — this one is by Khan Academy on YouTube. The practice questions and exit ticket below were drafted by AI for this objective, and every question is editable in the teacher guide.
Part 2 of 4
Key concepts
3 concepts
- 1
The width of pseud amonous bacteria is around one micrometer, while human egg cells have a diameter on the order of 100 micrometers.
- 2
The smallest bacterial cells discovered have a size of about a few hundred nanometers, and the limiting factor for cell size is the ratio of volume to surface area.
- 3
As a cell grows, the volume increases faster than the surface area, making it difficult for the cell to take in nutrients and get rid of waste.
Part 3 of 4
Practice
11 questions
What is the approximate width of the Pseudomonas bacteria shown in the video?
What is the limiting factor for how large a cell can get, as discussed in the video?
Part 4 of 4
Exit ticket
Quick comprehension check
“Explain how the surface area to volume ratio limits cell size. Be sure to include how nutrient and waste exchange are affected.”
Sample answer included in the free materials
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Teacher guide, student handout, and slides — free, in Google Docs format
Teacher Guide
Complete lesson plan with answer keys and alternate activities
Student Handout
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