Exchanging Materials 0.0 / 5 ? BiologyCells, tissues and organsIGCSEAQA Created by: Lotto65Created on: 21-12-15 14:39 What is the surface area: volume ratio of small organisms? Large 1 of 20 How do single-celled organisms gain necessary materials? By diffusion through the surface as they are so tiny 2 of 20 Why is it necessary to exchange materials? So oxygen and soluble food can reach cells for respiration and waste materials can leave efficiently 3 of 20 What surface area:volume ration do large organisms have? Small- decreases as the organism increases in size 4 of 20 Why do organisms with many cells need exchange surfaces? Many cells are not in contact with the environment so they need these surfaces to obtain all the oxygen and materials they need 5 of 20 What are the general characteristics of exchange surfaces? Thin walls; Efficient transport system; LARGE SURFACE AREA 6 of 20 What is the requirement for gaseous exchange surfaces? Must be ventilated 7 of 20 What is the gaseous exchange surface called in our lungs? Alveoli 8 of 20 What are the characteristics of alveoli? Thin walls; large surface area; good blood supply nearby 9 of 20 Why is it important for the alveoli to have a good blood supply nearby? To maintain a concentration gradient 10 of 20 Give two adaptations of plants to allow maximum absorption Long, thin roots to increase surface area+ root hair cells; Broad leaves 11 of 20 What are the characteristics of leaves to allow gas exchange? Flat; thin; Internal air spaces; stomata to allow gases in and out 12 of 20 Where in the digestive system are solutes absorbed into the blood? Small intestine 13 of 20 What lines the inner surfaces of the small intestine? Villi 14 of 20 What is the purpose of villi? An exchange surface for food 15 of 20 What are some characteristics of villi? Thin walls (1 cell thick); capillaries close by; finger shape increases surface area 16 of 20 Why is it good for villi to have thin walls? Short diffusion path 17 of 20 Why is it good for villi to have many capillaries nearby? Rich blood supply to maintain steep concentration gradient 18 of 20 Why is it important for the villi to have a large surface area? Greater rate of diffusion etc. so the most amount of solutes can be absorbed 19 of 20 How are solutes absorbed into the blood through the villi? Diffusion or active transport 20 of 20
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