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

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

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 1635-1703 Studied microorganisms Microscope ‘invented in 1590s’ still disputed Monks cells = cells

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 1635-1703 Studied microorganisms Microscope ‘invented in 1590s’ still disputed Monks cells = cells

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

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.

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

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

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

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.

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