Exam # 2 Study Guide Lectures: 8 - 18 Lecture 8 (February 17) !Distinguish animals from other lineages -multicellular -sexual reproduction -complex organ systems -eukaryotic -heterotrophs/predators -mobile (most) -no cell walls -development is governed by a unique conserved genetic network (hox genes) -most have muscle/nerve cells !Advantages of segmentation, bilateral symmetry (movement, cephalization, nervous system, defense) -Bilateral symmetry was an important development because it allowed for cephalization, or the making of a head — cephalization aids movement -set the stage for central nerve cord in many organisms —> became central nervous system -set the stage for appendages (also aided in movement and in defense) Distinguish bilateral and radial symmetry radial symmetry = can split it laterally and it has symmetrical sections bilateral symmetry = they must have a clearly defined front, back, top and bottom - the only animals that lack this are cnidarians and upward !!Lecture 9 (February 18) !Why was gastrulation an important innovation? -gastrulation = the formation of germ layers -important because the germ layers then determine what the rest of the body will ultimately become !What is the role of the germ layers (you needn’t memorize what they do, but what is their purpose generally)? -ectoderm — outer layer that becomes the nervous system -mesoderm — middle layer that becomes organs, skeleton, muscles, circulatory system -endoderm — inner layer that becomes the digestive & respiratory systems !!Bio 152!!If bilateral symmetry is an “ancestral” trait for echinoderms, how come they have radial symmetry? -because for any organism, they first have replications of identical segments/sections of the organism, and then specialization of segments -echinoderms most likely lost the trait for bilateralism because it was no longer advantageous for their lifestyle !Ancestral and derived traits — distinguish using a phylogeny, don’t memorize specific traits ancestral traits = one that is shared by the taxa (group of organisms) and includes ancestors derived traits = traits present in descendants that were not present in their ancestors **See phylogeny on lecture 8 and 9 slides** and !Be able to interpret a phylogeny - Which organisms have which innovations - What’s ancestral and derived? see question 7 on plant physiology and into to animal physiology quiz!! !!Lecture 10 (February 20) !Q10 and its significance -it is the temperature coefficient, telling the rate of change for a biological system over 10 degrees C -Calculated with the formula: Q10 = (R2/R1)10/(T2-T1) R is rate of reaction, T is temperature in degrees C -if there’s a temp change of 10 degrees it makes the formula just (R2/R1) !Based on the enzymes Km, which animal is the best adapted to the broadest temperature range? a.Trematomus b. trout c. rat • the rat Km is the most stable over a large range — a stable Km is better because it means that the rat is better able to more easily survive in a range of more temperatures!•what is more important for the cell is that the enzyme continues working the same way — even though the icefish has a lower Km (and lower = more efficient) it triples over the range of temperatures while the rat’s stays mostly the same •icefish would be best adapted to life in a cold environment (ectotherm) because it has the lowest Km at the colder temperatures (meaning that the organism has a higher ability to function when the Km is low) !Distinguish between physiological and behavioral adaptations to hot/cold physiological = circulatory adaptations too hot increase blood to organs that can radiate heat (countercurrent heat exchangers, large surface area with lots of circulation like ears for rabbits), adjusting metabolic heat production like shivering when cold behavioral = hiding in the shade to cool down by evaporative heat loss How can organisms exchange heat with the environment? 4 physical processes: 1.radiation = transfer of heat energy through the atmosphere electromagnetic radiation 2.evaporation = goes from liquid to gas using your heat 3.conduction = direct transfer 4.convection = conduction to a moving source like a fluid or a gas !Endotherm vs. ectotherm endotherms: maintain their body temperature (mammals) ectotherms: adapt their temperature to their environment (fish) Homeostasis and dynamic equilibrium — why can’t an organism just keep a totally steady temperature?!Because when an organism detects a change in their environment, they must adapt to that temperature change. They want to stay around a certain point (the set point) however there will be certain things happening in the body that make it impossible to stay at exactly the same temperature (fluctuates several degrees) - rat example: there are metabolic processes happening inside the body, like moving blood, that produce heat, therefore the body temperature will heat up so the rat will need to sweat or pant to cool the body back down again. These process are always happening, and so the body is constantly needing to adjust its temperature slightly to try and get it nearer to the set point. Integrator, sensor and effector sensor = structure that senses some aspect of the external or internal environment - warm and cold temperature receptors sense temp, send info to brain integrator = part of the nervous system that evaluates sensory information and “decides” if a response is necessary to achieve homeostasis (like the thermostat in your house) - neurons in the hypothalamus compare current temp to your set point and instruct effectors as needed effector = any structure that helps to restore the desired internal condition - changes body temp to match set point - decreases body temp: blood vessels near skin, sweat glands, respiratory centers (panting) - increases body temp: blood vessels near skin, muscles (shivering), cells (cellular respiration) How does negative feedback work? - when the regulatory system makes a change in the opposite diction to a change in internal conditions, or the products inhibit the process. Why is temperature homeostasis an example of negative feedback regulation? The body’s reaction to information is trying to offset it in the opposite direction — when the temperature is too high (animal gets too hot) it wants to force it lower, and when the temperature is too cold it wants to force it higher. !!Lecture