114090
Description
Flashcards by sammi_taylor01, updated more than 1 year ago
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Created by sammi_taylor01
over 11 years ago
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| Question | Answer |
| Give four examples of things that need to be interchanged between an organism and its environment. | -respiratory gases -heat -excretory products -nutrients |
| What two different ways can this exchange occur in (include examples as well) | -actively, e.g. active transport which goes against a concentration gradient -passively, e.g. diffusion or osmosis which goes down a concentration gradient. |
| What two factors affect the amount of each material that needs to be exchanged? | -size of an organism -metabolic rate of an organism |
| What increases the efficiency of how much a substance is exchanged? | surface area to volume ratio |
| Give some examples of features of specialised exchange surfaces. | -large surface area to volume ratio -thin diffusion pathway -partially permeable membrane -movement of internal/environmental mediums to maintain a gradient. |
| Give the equation for working out diffusion. | surface are X difference in concentration --------------------------------------------- length of diffusion path |
| What is a disadvantage of a thin diffusion pathway and how do we overcome it? | They are easily damaged, therefore they are often located inside an organism for protection. |
| What is the surface area to volume ratio like for: 1) small organisms 2) large organisms | 1) large surface area to volume ratio 2) small surface area to volume ratio |
| For organisms with a large surface area to volume ratio, organisms have evolved to have the two following features which help overcome the problem: | -a flattened shape so no cell is far from the surface -specialised exchange surfaces with a large surface area (e.g. gills in fish, lungs in mammals) |
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