1. Your body is a machine made up of many different systems Put the following in size order from smallest to largest: Organ system Tissues Cells Organism Organ

3. Inquiry Question: How does my body work?
Explain the importance of surface area to volume ratio in terms of cells and diffusion
Gold
Describe surface area to volume ratio and diffusion
Silver
Describe cell theory and the common features of cells
Bronze

4. Cell Theory All organisms are made of one or more cells
Cells are the smallest units of life
One cell can perform all functions of life
Cells vary in shape and size but have some common features…
Unicellular = made of one cell
Multicellular = made of more than one cell
Studied microorganisms
Microscope ‘invented in 1590s’ still disputed
Monks cells = cells

5. Common cell features
Every living cell is surrounded by a membrane, separating the cell contents from everything else
Cells contain genetic material – storing all instructions for cell activities
Enzymes inside cells catalyze reactions
Cells create their own energy
Nothing smaller than a cell can survive on it’s own
Studied microorganisms
Microscope ‘invented in 1590s’ still disputed
Monks cells = cells

6. Surface Area: Volume
Smaller cells have a larger surface area compared to their volume. Whereas larger cells have smaller surface area compared to their volume Surface area: the outer most layer of the cell Volume: the amount of space a cell occupies

7. Surface Area: Volume
Important to cells as they use DIFFUSION to transport some materials into and out of the cell (nutrients, oxygen, water, waste)
Larger cells have less surface area for their volume to bring in the materials that the cell needs, and to get rid of waste.

8. Surface Area: Volume
Smaller cells have lots of surface area compared to their volume to do this. This limits the size of cells Reactions inside the cytoplasm would not work well otherwise

9. Diffusion
Diffusion is where a substance moves from a high concentration to a low concentration

10. Inquiry Question: How does my body work?
Explain the importance of surface area to volume ratio in terms of cells and diffusion
Gold
Describe surface area to volume ratio and diffusion
Silver
Describe cell theory and the common features of cells
Bronze

11. Your Practical Assessment: Criteria B & C
How does surface area to volume ratio limit the size of cells? Investigation into rate of diffusion for different surface area:volume
Plate of agar soaked with phenolthalein
1 x Large bottle of Hydrochloric acid
1 x 100mL beaker
1 x 30cm ruler (you need to provide this)
1 x pair of forceps
1 x Scalpel
1 x Stop clock
Tuesday 3rd
Intro and planning
Friday 6th
Planning
Tuesday 10th
Practical work
Wednesday 11th
Write up results
11th – 18th
Homework: finish whole report
Tips:
Agar is pink in colour due to phenolthalein
Agar will turn clear when hydrochloric acid touches it
You are investigating the rate of diffusion of HCl into different sizes of ‘cells’ (agar cubes)
You need 3 repeats for each size of ‘cell’ and take an average of what ever you decide to measure
HAND IN ON 18TH OCTOBER: TURNITIN AND HARD COPY
IF YOU ARE AWAY YOU NEED TO JUST HAND IN ON TURNITIN. NO EXCUSES.

12. Dimensions (mm)
Surface area (mm2)
Volume
(mm3)
SA:volume
Test 1
Test 2
Test 3
Average
5 x 5 x 5
10 x 10 x 10
15 x 15 x 15