Why would enzymes have different optimums

Plenary Write a conclusion for the following results Temp (oC) Gas produced (cm3) 10 5 20 17 30 23 40 55 50 45 Write a conclusion for the following results What is the trend? What science explains the trend

Starter Organise these sentences to give a definition for diffusion. (Use page 9 of the book to help if needed) from an area of higher concentration Net movement of particles until equilibrium is reached to an area of lower concentration

Why do we need diffusion? What process occurs in all cells and is essential to life? Respiration (aerobic) A B C What substances need to enter the cell for respiration to occur? Oxygen and food (glucose) What products of respiration need to leave the cell? Carbon dioxide and (excess) water Oxygen, carbon dioxide and glucose move by diffusion, they diffuse across the .

Examples of where diffusion is important Between air in alveoli to blood (oxygen and carbon dioxide) From the small intestine into the blood (digested food) From the mothers blood into an unborn childs across the placenta What factors affect the rate of diffusion? How can we make it faster/slower?

So how can we make diffusion faster? Fick’s law All organisms need to exchange substances such as food, waste, gases and heat with their surroundings. These substances must diffuse between the organism and the surroundings. The rate at which a substance can diffuse is given by Fick's law: Rate of diffusion = surface area x concentration difference Distance So how can we make diffusion faster?

Increase surface area of the tissue Increase the concentration gradient (bigger difference between the concentrations) Decrease the distance it has to travel through (less cells) We need to look at how particular substances manage to do this Alveoli Small intestine Placenta

Way(s) that this is achieved Increasing diffusion rate in the lungs Use pages 10+11 to complete the table Way(s) that this is achieved Large surface area Shape of the alveoli – folded surface Maintenance of steep concentration gradient Constant replacement of air in lungs to keep oxygen concentration high Constant removal of oxygenated blood and delivery of deoxygenated blood Short diffusion pathway Alveolus and capillary are only one cell thick (few membranes to cross) Thin cells

What other adaptations do the alveoli have? Moist – maintains permeability Permeability of cells – allow gases through easily

Way(s) that this is achieved Increasing diffusion rate in the small intestine Use pages 11+12 to complete the table Way(s) that this is achieved Large surface area Villi and microvilli Maintenance of steep concentration gradient Constant removal of nutrient rich blood and delivery of nutrient deficient blood Short diffusion pathway Blood vessels protrude up the villi Villi have one cell between the intestine and the blood vessels collecting food

Way(s) that this is achieved Increasing diffusion rate at the placenta Use pages 11+12 to complete the table Way(s) that this is achieved Large surface area Many folds Maintenance of steep concentration gradient Constant replacement of mother and foetal bloods Short diffusion pathway Mothers blood and foetus blood come very close together without mixing, they are separated by thin walls of tissue

Plenary Complete the sheet from what you have done today in the lesson Glue in Hand in your books for marking