Embedded Files
Diffusion
KEy question: How do cells move substances between them?
KEy question: How do cells move substances between them?
Task 1 - Watch
Task 1 - Watch
Watch this short video on diffusion then answer the questions in task 1 of the companion sheet.
Task 2 - Simulation playtime
Task 2 - Simulation playtime
Imaging this cell is in the alveoli. Outside the cell is a nice lung full of air that is rich in oxygen. Inside the cell there is no oxygen but lots of the waste gas Carbon dioxide.
Spend 5 minutes playing with the simulation, then follow the instructions on the companion sheets to complete the virtual experiment.
Surface area and volume
Surface area and volume
What are these and how do the affect diffusion?
Have a look at these cubes - They are all different sizes and volumes.
Surface area to volume ratio is a measure of the amount of surface area (like skin or a membrane on a cell) compared to the volume of the object. This concept is common in science and there are lots examples of it. As an object gets smaller (or as it gets broken into smaller and smaller pieces) the object increases the amount of surface area compared to the volume of the object. This is why granulated sugar dissolves much faster than the same volume of sugar cubes. The granulated sugar has much more surface area.
So, following on from this, if a cell has is very small and has a large surface area, is has a high surface area to volume ratio. This means that there are more 'places' where substances can pass through the cell membrane. A bit like trying to empty a football stadium through 30 exits rather than just 1. This means that the higher the surface are to volume ration, the faster diffusion can take place.
TASK 3 - Complete the table on the companion sheets
TASK 3 - Complete the table on the companion sheets
Task 4 - Elephants and amoebas
Task 4 - Elephants and amoebas
Answer last 4 questions on of the companion sheet.
Page updated
Google Sites
Report abuse