WSU Biology 106 exam 4QUESTIONS AND CORRECT DETAILED ANSWERS WITH RATIONALES

WSU Biology 106 exam 4QUESTIONS AND CORRECT DETAILED ANSWERS WITH RATIONALES Organisms that rely solely on surface - ANSWER- colonial choanaoflagellate Other small organisms that use their surfaces only - ANSWER- bacteria, microalgae, yeast How can you be bigger than 1mm? - ANSWER- adaptations to enhance gas exchange: circulatory systems and increase surface area Gas exchange structures - ANSWER- Surface only (less than 1mm) Gastrovascular cavity (hydra, jellyfish, flatworms) have increased surface area Gills, tracheal systems, lungs also increase SA A mixture of the above Increased surface area example: - ANSWER- Green hydra: several mm long, phylum cnidaria Jellyfish Aurelia - ANSWER- Has a complex gastrovascular cavity that circulates fluid Gills - ANSWER- Appendages around which the medium (water) passes through Richly supplied with blood vessels Found in many invertebrates and vertebrates Outside the body compared to inside like lungs Fish gill - ANSWER- Rather than being a solid structure, its finely subdivided to enhance gas exchange area Gill filaments - ANSWER- Thin walled and finely divided elements that provide a lot of surface area which exchanges oxygen and CO2 Lamellae - ANSWER- Offshoots of the filaments, contain small blood capillaries and blood flows in the opposite direction of the water Countercurrent flow - ANSWER- Water flows in the opposite direction of blood to maximize the amount of oxygen blood can pick up As blood flows through the gills and gains oxygen from the water, it encounters fresh water with higher oxygen concentration that offloads oxygen into the blood. Low oxygen blood meets low oxygen water, oxygen flows from water to blood How does countercurrent flow enable more complete removal of oxygen from the water? - ANSWER- Oxygen exchange allows the blood to pick up 90% of oxygen in the water because the percentage of oxygen concentration is in opposite directions Are gills effective in increasing surface area? - ANSWER- In mackerel, a 20 fold increase due to gills, over 1 square METER How do gill surface areas compare among different fishes? - ANSWER- Numbers correspond to arbitrary units per gram body weight Mackerel has more than a goosefish because goosefish don't need gills since they are poor aerobic swimmers Tracheal systems in insects - ANSWER- Air filled tubes that extend into the body, small insects have passive diffusion only while large insects "breathe" Air sacs vs tracheae Tracheoles supply tissues - ANSWER- Connect to the body cells and the air that comes out uses diffusion which is a short distance from the tracheal to the mitochondria Tracheal system limits the size of insects - ANSWER- Dung beetles provide an opportunity to investigate the effect of body size on the tracheal system Some prehistoric insects had wings as long as a human arm, why? - ANSWER- Thicker exoskeleton to resist gravity Air oxygen levels 30% compared to current levels of 20% Abundant nutrients from feeding on dinosaur