A sugar alcohol that is a common cryoprotectant (antifreeze) in poikilothermic animals; lowers freezing point.

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1 Physiological Ecology, Bio 31 Second Midterm exam 21 May 2015 (112 possible points) Name: Matt 15 pts 1. Briefly define each of the following terms. Glycerol - A sugar alcohol that is a common cryoprotectant (antifreeze) in poikilothermic animals; lowers freezing point. Ribeiroia - A trematode parasite that causes limb deformities in some frogs. Other hosts inlcude snails and birds. Phenology - the annual timing of life history events Climatic envelope hypothesis - the proposition that geographic distributions can be understood as a range of suitable climatic conditions Heat shock protein - proteins that are expressed under high temperature and apparently confer protection to celllular and biochemical systems at high temperatures. Highly conserved in evolutionary time. 8 pts 2. Draw two functions on the graph at right to indicate the partial pressure of oxygen in water and blood across the respiratory exchange surface of a trout. Label the lines Water and Blood. Draw an arrow next to each function indicating the direction of flow. Briefly explain how this system works to the benefit of the trout. Favorable diffusion gradient for O 2 is maintained across full length of lamellae 8 pts 3. In the left column indicate specific physiological problems that would be faced by an Atlantic herring (small marine fish) that you transplant to the Swift Diamond River in the Second College Grant? In the right column indicate how a brook trout in the Swift Diamond River solve these problems? Problems Solutions )))))))))))))))))))) ))))))))))))))))))))))))))))))))))))))) Loss of ions Gain of water Mucous; active uptake of ions from water (especially in gills) Mucous; dilute, copious urine 4 pts 4. Why isn t the hemolymph of insects red? Insect hemolymph does not function in oxygen delivery, hence there are no oxygen carrying pigments (e.g., hemoglobin), which are what give blood its red color. 6 pts 5. How do desert kangaroo rats succeed in matching their water requirements to their water supply? Water loss is minimized by: producing concentrated urine; by producing dry feces; by exploiting a den and nocturnal habits to minimize evaporative losses. Water gain comes chiefly from metabolic water (their diet has only very low water content) page 1

2 10 pts 6. How did the studies by Culler et al of mosquitoes in Greenland relate the figure at right? The theoretical model represented in the figure predicts that warming temperatures will favor predators over herbivores. However, studies by Culler et al. Indicated that warming temperatures favored mosquitoes over their prey by accelerating mosquito development rate (and therefore reducing the duration when mosquito larvae are exposed to predators) more than predation rates. In this case the expected result is increased survival and abundance of Greenlandic mosquitoes under a warming climate. 6 pts 7. A bizarre deep-sea fish has recently been discovered to be a surprsingly good homeotherm. Based on principles of physiollogical ecology, what would you predict to be the approximate body temperature of this strange fish? Explain briefly. Many taxa have independently converged on operating body temperatures that are about C. This is apparently an optimal zone for biochemical and neuromuscular performance. One could predict that this fish would be as close to C as the thermal environment permits. 6 pts 8. Refer to the data traces at right taken from a moth pupa. Label each of the three (A-C) as one of the following: (1) O 2 uptake from vessel containing the pupa; (2) CO 2 output into the vessel containing the pupa; (3) ph 2 O within the tracheal system; (4) pco 2 within tracheal system; (5) po 2 within tracheal system. Label as O, F, and C, the times when spiracles are open, fluttering, and closed, respectively. 7 pts 9. Two lakes have the same Hg content in the water and the same community of zooplankton and fish. The zooplankton eat phytoplankton and the fish eat zooplankton. The lakes only differ in the species of phytoplankton, phytoplankton A vs phytoplankton B. Phytoplankton B is about like A except that it is more nutritious to the zooplankton, so zooplankton grow faster in lake B. In which lake will the fish tend to have higher concentrations of Hg in their tissue. Circle one. Lake A Lake B No way to predict Briefly explain your answer. Given similar assimilation rates of Hg by the phytoplankton A and B, zooplankton (and therefore the fish that eat the zooplankton) will tend to attain higher concentrations of Hg when eating the phytoplankton that yields the slowest growth rate of zooplankton. page 2

3 12 pts 10. The Secretary of the Interior is on the phone. She is concerned about possible effects of UV-B radiation on vertebrate populations in national parks and forests across the country. She wants to initiate a research program that will monitor populations at high risk, but of course has limited financial resources and can only monitor a limited number of populations. She wants your help in developing a fast, cost-effective, strategy for identifying those species and/or populations that are most likely to be impacted by UV-B radiation. Outline such a strategy and briefly explain your rationale. 1. Identify regions with high UV-B radiation (probably high altitude regions) 2. Focus on amphibians because their aquatic eggs are permeable to UV-B radiation 3. Screen amphibian species for low photolyase activity, because photolyase activity is inversely correlated with developmental damage from UV-B radiation 4. Do a literature review and survey knowledgeable naturalists to identify species and populations that lay eggs in shallow water in habitats that are exposed to direct sunlight. 5. Select populations for monitoring that are at risk with respect to all four of the above conditions. 6. For a control, also monitor some species thought to have low photolyase activity and/or low exposure to UV-B. Some other strategies could be equally defensible. 10 pts 11. Some varieties of cotton produce relatively high concentrations of condensed tannins in their leaves. The tannins increase larval mortality in insect pests. Unfortunately, these well defended genotypes have lower growth rates and yield less cotton in the absence of pests. It has been proposed that pesticide use could be reduced by inter-planting cotton genotypes that produce different concentrations of condensed tannins in their leaves (while keeping the average concentrations of tannins the same). Identify the general conditions under which cotton fields with high variance in tannins (but the same average tannin concentration) would have less susceptibility to insect pests. By Jensen s Inequality, increasing the variance among plants in tannin concentration would tend to decrease survival of pests when survival as a function of tannin concentration is decelerating (region A at right) but would tend to have the opposite effect when this same function is accelerating (e.g., as in Region B at right). page 3

4 8 pts 14. Identify two fundamental ways in which the physiological ecology of plants are the same and different. Two ways in which plants and animals are the same. 1. Active transport required to move solutes against a diffusion gradient. 2. Gas molecules (e.g., O2 or C02) need to go into solution to cross a cell membrane 3. Gases move across membranes according to Fick s Law of Diffusion 4. The rate of biochemical processes increases with temperature at about 2x per 10 C. Others Two ways in which plants and animals are different. 1. Plants are modular 2. Plants are autotrophs 3. Plants mine 4. Most animals have a neuromuscular system Others 12 pts 15. A friend in Vermont owns a trout stream whose banks are lined with valuable oak trees. She is tempted to have the trees logged, but is concerned about possible effects on the trout population. She knows that you have studied physiological ecology so comes to you for guidance. Provide her with a list of physiologically explicit mechanisms by which removing the trees might affect her trout over the next 10 years; consider both direct and indirect effects. 1. Loss of canopy increases exposure to sunlight which increases stream temperature. Prior research shows high susceptibility of trout to warm water due to increased metabolic rates in combination with reduced O 2 content. 2. Loss of leaf input may reduce abundance of invertebrate prey that depend upon litter input for food. 3. Changes in litter input to surrounding forest can influence the chemistry of water that runs over or through the forest soil before entering the stream. Changes in ph and/or conductivity could have direct effects on trout physiology (e.g., function of respiratory enzymes and osmoregulation) or indirect affects on trout via affects on the physiology of invertebrate prey items. 4. Increased erosion and sediment accumulation in the stream can be deleterious to developing trout eggs, which require well oxygenated water during development. Erosion and sedimentation could also have deleterious effects on invertebrate prey items (e.g., netspinning caddisflies cannot maintain their nets with high sediment flow). 5. Increased exposure to UV radiation could increase mortality of trout embryos, trout fry, or invertebrate prey items. 6. Reduced input of coarse woody debris (stems, branches, and trunks) may reduce the availability of refuges for fish (forcing them to feed less or suffer greater predation risks) and reduce substrate used by invertebrate prey items (caddisflies, etc.) Mark each entry in your list with a "1", "2", or "3", with a "1" indicating those mechanisms with the greatest potential to impact the trout population, and a "3" indicating those with the least potential to impact the trout population. Briefly explain your reasoning for those that you have marked with a "1". Many could be defensible with sound reasoning. page 4

5 Number students 2 1 Bio 31: Spring 2015, 2nd exam Mean = 84 SD = 6 Pages graded Approximate grades >93 A A B B B C+ 1-4 Matt 0 Number students Bio 31: historical 2nd Exam Mean = 76 SD = >99.5 Points on exam

Biology 110 Organisms & Environment Desertification Unit Page 1 of 7

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