Note: Some of these questions are specific to last year’s 112 class. I’ve changed some of the lectures and may not have covered a particular topic this year that would allow you to answer all questions completely.
1. Explain the concept of negative feedback. Contrast that with positive feedback.
Feedback information can either reduce/reverse a process, or amplify it, depending on whether it is negative or positive feedback. Negative feedback maintains a particular parameter or value close to a set point, while positive feedback takes the value away from the set point. Negative feedback thus maintains homeostasis, and is usually used to bring a positive feedback response back to a set point after the signal amplification is completed.
2. For the following animals describe how two adaptations of the respiratory system increase Q in Fick’s law of diffusion. Be SPECIFIC.
a. Fish: countercurrent exchange in gills, short diffusion distance, filaments and lamellae increase surface area
b. Insect: tracheoles keep oxygen in air (higher coefficient of diffusion than in water), short diffusion distance, much surface area at ends of tracheoles
c. Mammal: huge surface area with alveoli, short diffusion distance, perfusion keeps concentration gradient somewhat high, air breather
d. Bird: one way flow maintains high concentration gradient, air breather, large surface area in lungs
3. Using specific examples, compare and contrast open and closed circulatory systems. For one of the two, explain why that type of circulation might be advantageous to the animal, especially in relation to other aspects of the animals’ biology.
Insects, for example, have open circulatory systems, and annelids have closed circulatory systems. They both have hearts that pump blood and vessels that carry blood through at least part of the body. In open CS, blood bathes the tissues, and has no cellular component (i.e., no red blood cells). This is not a disadvantage, since the CS does not transport gasses. Exchange of nutrients and wastes occurs as tissues (and cells) are bathed. Excretion also occurs as hemolymph (insect blood) moves past Malpighian tubules. In the closed CS of the earthworm, separation of blood from coelomic fluid is essential for the ability of the coelom to act as a hyrdostatic skeleton. Also, there is no tracheal system, so gases must be transported in the closed CS. These are some examples of possible answers...
4. Endotherms and ectotherms use dissimilar strategies for regulating body temperature; describe two such strategies for each type of animal, in one sentence each.
Ectotherms will often use behavioral thermoregulation, with little metabolic heat generation. Metabolic rates are generally lower, and thus less heat is produced. However, this allows them to eat less and be less active at certain times of the year or day. To maintain a body temperature closer to their setpoint than if they did no thermoregulation, they will move towards or away from heat sources. They also have the ability to regulate blood flow to extremities via local autoregulation and changes in heart rate.
Endotherms can behaviorally thermoregulate, but primarily use metabolism to generate heat and maintain a fairly constant body temperature. Local control can alter blood flow to retain heat or lose excess heat.
5. The three organ systems that deal with excretion, nutrition, and circulation are closely tied together. Provide two detailed examples of this integration.
Integration is accomplished in a number of different ways. One example is the ingestion of potentially toxic compounds in food. After ingestion and absorption, the hepatic portal system of the CS will bring food molecules and toxins from the digestive tract to the liver. The liver may metabolically break down the toxin, if able, and then the CS will carry the toxin to the excretory system. If toxin breakdown products are small, water soluble molecules, they will be excreted by the kidney.
If blood pressure in the renal artery is too low, the kidneys will secrete hormones, which can cause an increase in thirst, change characteristics of the CS, causing increased heart rate or constriction of arterioles in the extremities, and more water resorption in the kidneys themselves. You will need to be very specific in your examples.
6. List and describe briefly two evolutionary trends observed in both Protostomes and Deuterostomes.
Both evolved into terrestrial forms from marine species. Both evolved early in their history as filter feeders (that was a common food acquisition mode). Both have increased in diversity over time.
7. Compare and contrast adaptations of earthworms and spiders that increase survival in the habitat in which they reside and/or consume the food they consume.
Consider adaptations of the digestive system that might be important for the type of food they consume. Earthworms ingest soil and detritus and have gizzard for grinding up leaf litter and other food. Their hydrostatic skeletons and segmentation are adaptations that help them burrow through soil. Spiders are also segmented, but because of their exoskeleton and open CS, they do not have, nor do they need, a hydrostatic skeleton. Other adaptations that spiders have are in their complex behaviors used to capture prey and recognize mates.
8. How do the endocrine system (hormones) and the circulatory system maintain homeostasis in the digestive system? Be specific.
Check your notes and text - we went over specific examples... Or check back later...
9. While out doing research in Rocky River I discovered a new species of insect living at the bottom of the river. Based on your knowledge of physiology and your powers of deduction, help me answer the following questions.
a. Is this animal an osmoconformer or osmoregulator, and why? Probably an osmoregulator, since it is in freshwater and can't survive with solute concentrations as low as in freshwater.
b. What mechanism of gas exchange is it likely to have? Probably gills, especially if it's at the bottom of the river, rather than swimming near the surface. However, it is should still have air-filled tracheoles with the body, but they don't open to the external environment, they would exchange gases at the gill surfaces via diffusion.
c. In what form and from where does it excrete nitrogenous waste? Likely ammonia, from malpighian tubules, which connect to the gut.
d. If I told you that I found it attached to a rock, what might you suspect is a likely way that it forages for food? Through filter-feeding
10. Apply the concept of countercurrent exchange to the following three systems. For each, identify the specific matter or energy that is exchanged, and the system(s) involved in the mechanism:
a.
Mammalian kidney: Exchanges solutes (retains some, excretes others),
retains water. Involves the circulatory and excretory systems, and the nephron
acts as a countercurrent multiplier, ultimately pulling more water out of the
filtrate and concentrating the urine 2-12x plasma concentrations.
b. Bony fish gill: Exchanges oxygen and carbon dioxide (and ammonia). Involves
or is part of circulatory, respiratory, and excretory systems. Countercurrent
exchange is primarily used in gas exchange, and not so much for ammonia excretion,
and having water flow opposite to blood flow, gills are much more efficient
than concurrent flow and can extract a much higher percentage of oxygen and
get rid of more carbon dioxide.
c. Arctic wolf legs: Exchanges heat from arteries to veins. Involves circulatory
system only. Heat flows from arteries, which are coming from the core of the
body, to veins that run close by and parallel to the artery. Heat passes from
the arterial blood to the blood in the veins, which returns to the body core.
Extremities are kept at a lower temperature, and thus lose less heat to the
environment.
11. Discuss the integration of up to four (4) systems that we’ve studied (besides the reproductive system) and how they specifically affect or are affected during mammalian reproduction. Use only one sentence for each example (>1 example can come from the same system). Each example will be worth 10 points divided by the total number of examples you use (e.g., if you choose 2 examples, they will be worth 5 points each; 4 will be worth 2.5 each).
Circulatory system is integral in transporting hormones from endocrine glands to target sites. A specific example is...
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