| Why do we need to exchange surfaces? | To allow the organism to live by transporting oxygen glucose and getting rid of waste products |
| Why is it easier to diffuse in single cell structures then multi cell structures | Substances have to travel not very far and they have a larger surface area: volume. This means it can diffuse enough substances to reach the demand of the volume.
Multi cell structures have cells too deep inside meaning the joruney is too long and the surface area cant reach its demand of getting enough substances for its volume |
| What do Multi cell strucutres do differently? | They have specialised exchange organs with a specialised exchange surface to help the demand |
| What else do Multi cell strucutures have? | They have transport system to ensure the substances get to the cells needing it. It is also to get rid off waste products. |
| Examples of Transport Sytems? | In the Plant, you have the Xylem and Phloem. Animals have the circulatory system. |
| How are specilaised exchange organs adapted? | They are thin. The substances have a short distance to travel
They have a large surface area : volume ration
The Cirulatory System has millions of blood vessels to get stuff in and out of cells. same with Gas Exchange. |
| How does Gas Exchange happen? | This happens in the Lungs where oxygen is transported to the bloodstream. How this happens comes down to the alveoli where it happens. The Alveoli are adapted to this by having:
Massive surface area : Volume ratio, Tiny walls, A moist lining for dissolving gases and a good blood supply.
The Capillary next to the Alveoli gives it Carbon Dioxide and in return gets Oxygen. The Blood in the stream is Deoxygented [no oxygen but lots of CO2] so diffusion can happen quickly.
The oxygen is diffused in and is now carried to its destination |
| What is special about the Villi | They are adapted too. Found in the insides of the Small intenstine they help with the dissolved food molecules going into the blood. They are a single layer of surface cells and have a massive amount of blood supply. |
| How are Leaves adapted? | Leaves need Carbon Dioxide for Photosynthesis and Oxygen for Respiration. Obviously when they are doing one of the two, the concentration will be higher outside which means diffsusion.
Leaves makes it more quicker and easier. They are broad [larger surface area : volume] and are thin which makes the distance not far for the gases.
They have air spaces inside it to let the gases to move at ease and also increases the ratio.
Stomato at the bottom of the leave also lets the gases diffuse in/out They also allow water to escape [Transpiration] |
| How are Root Hair cells adapted? | They have long hairs which stick into the soil outwards. These hairs will cover the branches of the root which increases their surface area : volume ratio.
Water can be in without fuss, the water potential outside is greater but the minerals have to be forced in [active transport] This is because the concentration is higher inside. |
