practice midterm Flashcards
List 3 specific examples of where homeostasis occurs. Be specific and include an example animal. (3)
Dipole interactions make ice less dense than water, and so animals overwintering under ice must cope with hypoxia. Describe two ways animals do this. Be specific to animal and mechanism. (2)
some frogs flee to denser cold water at the bottom of a body of water, where they can remain by lowering metabolic rate and reducing energy consumption
other animals, such as fish, enter a “resting state” where they reduce heart rate and energy consumption.
Compare and contrast molarity and osmolarity with respect to cell size, and osmosis. Use example solutes, please. (3)
Name two energetically active transporters that maintain organism osmolarity in a fish gill. (2) What must happen when a freshwater fish transitions to seawater? (1)
PNA- cells actively uptake Na+ ions while PNA+ cells actively take up Cl- ions. When fish transition from freshwater to seawater, they transition from being hyperosmotic to hyposmotic; they must adapt to retain water since it will otherwise move down its gradient outside of the fish.
Phospholipids are amphipathic. What does this mean? (1) Why must they be this way (how does this ensure cellular homeostasis)? (1) How are phospholipids changed as an ectotherm adapts to winter life? Be specific! (1)
the amphipathic nature of phospholipids means that it contains both hydrophobic (phosphate/choline head) and hydrophilic (tail) components. this is important to ensure many ions and other particles cannot easily diffuse across the phospholipid bilayer. As ectotherms adapt to winter life, they are forced to introduce unsaturated bonds to the phospholipid bilayer to counteract the increased rigidity that colder temperatures engender.
Why exactly might a frog have more LDH than a toad? (1)
as LDH is used in the production of lactic acid from pyruvic acid, frogs are likely more adapted to physical mechanisms of defense. this would be exemplified in higher endurance, as frogs will be able to do supramaximal anaerobic work.
How would one type of enzyme (e.g. isoforms of LDH) maintain constant functionality despite being in different thermal environments? Why bother? (2)
certain enzymes like LDH have undeniable importance in extending exercise beyond what is normally capable, and so functionality in a wide range of environments is important. An organism may adapt to this by introducing more mobile in warmer environments.
Enzymes can be regulated in a variety of means. List two ways to increase the formation of product. List two ways to reduce the formation of product. (2)
increase:
- amplification, where one enzyme affects the activation of multiple other enzymes
- allosteric modulation, which decreases Km
decrease:
- allosteric inhibition, which increases Km
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Why do citrate and AMP have antagonistic roles for PFK? (2) Hint: mass action.
citrate decreases PFK activity, while AMP increases PFK activity. these are different products of PFK, so they can regulate PFK based on their relative concentrations.
If you are going to be a slow moving predator, best be lethal. How does alpha-conotoxin work exactly? What would happen if it had a higher Km than it does normally? (2)
alpha-conotoxin competes with acetylcholine for ligand receptors. a higher Km implies a lower binding affinity; this would mean that alpha-conotoxin would be less likely to bind, and thus be relatively ineffective to what we really occurs.
How exactly does a GPCR work? Describe the key components and their activity at the cellular membrane only. Use appropriate naming. (2)
G Coupled Protein Receptors work by receiving a ligand, which activates a nearby G protein. From there, the G protein activates another relevant enzyme.
An example of this is the adrenaline, which binds to a receptor and activates a G-coupled protein. This protein in turn activates adenyl cyclase, which begins the production of cAMP.
- What animal that we discussed will have an RQ of nearly 1? How does it facilitate this? (2)
hummingbirds have a RQ of nearly 1, due to their diet consisting primarily of sugars.
- Some animals are anadromous. Why bother? In the opposite manner, some animals are catadromous… why do this? Be a scientist and hypothesize. (2)
- Over an organism’s lifetime, it may change what energy is used for. In the very short term, how might we change energy? As we grow and develop, how might it change? What might Covid do to our energy allocation? (3)
In the very short term, we can change energy depending on the duration and intensity of exercise, which may change sources from phosphagens to blood glucose to fats. As we grow and develop, energy is partitioned to different areas, from growth as children to gamete production during age. COVID may change this energy allocation to creating more antibodies devoted to addressing the virus.
- What is the purpose of fasting animals before measuring physiological responses? (1)
to ensure the specific dynamic action has finished
