BIO 10130 Final Review

What does "hitting the wall" mean and what groups are more susceptible to this process?

"Hitting the wall" is the process in which endurance athletes (typically marathon runners) run out of glycogen stores in the muscles/liver and must convert to using fat as the alternative energy source. Men "hit the wall" more than women. This may be due to an evolutionary change in female physiology due to metabolic demands of embryo development during pregnancy. Female physiology seems to make a transition from carbohydrate (glycogen) metabolism to lipid (fats/oils) more quickly than men, hence a shorter (or non-existent) period of time ('hitting the wall") taken to make the switch when glycogen runs out.

What is stereoscopic visision and how does it help arboreal Primates?

...Is the placement of both eyes to the front of the head so that vision from both eyes overlaps considerably with the other allowing the brain to triangulate distance from the eyes. With two eyes viewing the same object --one eye-- no depth perception. Easier to tell how far away the branch is when leaping from tree to tree.

When an endotherm experiences cold stress, what are three ways they create heat?

1) they can increase their cellular metabolic rate 2) brown fat, a specific tissue type for generating heat, not storing fat. Cells of brown fat tissue have some fat store, but not enough to appear white like regular adipose tissue. The cells are packed with mitochondria that have few/no proton channels with ATP synthase attached. Protons can still pass thru the inner membrane of the mitochondrion, but as there is no ATPsynthase, no ATP is produced as the H+ goes down its concentration gradient. 3) they can increase voluntary muscle activity, such as waving arms or stamping feet; these create heat because working muscles uses energy from popping one phosphate from ATP resulting in ADP and a phosphate. Some of that energy is used to contract muscle while some gets away-- released as heat --a byproduct of muscle activity. 4) they can shiver, which is involuntary, simultaneous contraction of antagonistic muscle groups; because shivering is inefficient it is a last resort to keep body temperature up. It generates heat the same way as 3).

When an endotherm experiences cold stress, what are three ways they reduce heat loss?

1) they can vasoconstrict in the periphery, reducing blood flow to the periphery and thus preventing some heat from radiating off through the skin. 2) they can reduce their surfaceto volume ratio by huddling with others or curling up into the fetal position. 3) they can seasonally increase insulation by a) growing down or under fur, then in the short term (colder temps or night time) by b) piloerection (fluffing feathers in birds or erecting guard hairs so underfur can fluff up)

How does the immune system respond to when a cut gets infected? What is this response similar too?

A cut that is infected gets inflamed through redness, swelling, and heat, so the body vasodilates to send more blood with immune system responses to the region where the cut is in order to help it heal. This response is similar to how the immune system responds to the inflammation in atherosclerosis.

What happens to endotherms when the ambient temperature gets so hot?

As temperature gets super hot, enzymes in the endotherms begin to denature- without the proper active site in the enzymes, metabolic rate begins dropping, this is called hyperthermy.

Explain why organisms with amniotic eggs cannot use the same waste product as amphibians and fish, and instead use uric acid.

Amphibian and fish eggs, which allow the exchange of water between the egg and surrounding aquatic environment, can afford to use the highly toxic waste product ammonia, because they can easily keep the ammonia diluted with lots of water. However, amniotic eggs, which block water loss, have a limited amount of water inside the egg, and must use a more water-conservative and less toxic waste product. Uric acid is both less soluble and less toxic, and is a good waste product to have trapped in an egg with a developing fetus. Uric acid also conserves water because when waste is moved away from the embryo, uric acid precipitates into a solid packet at the edge of the egg, returning water to the internal environment.

What differentiates amphibians from reptiles?

Amphibians are aquatic or terrestrial, but they must lay eggs/have early development in water. Reptiles are fully terrestrial (because of their amniotic egg!).

Why did bipedalism arise as the climate changed?

Arboreal primates did not have a need for locomotor efficiency since they have access to a high and uniform density of food. However, out on the grassland/savanna, the arid, open climate causes food to be sparse and clumped, necessitating more efficient motor capabilities. Thus, with the change in climate, bipedality was a significant benfit to those primates venturing out of the forest into the savanna. Being bipedal also allowed primates to have a better view of the landscape to see predators or food, since their head physically sat above the grass.

Why would it be inefficient for bears to hibernate?

Bears are very large animals, and hibernation requires lowering the metabolic rate as low as possible, which results in the body temperature dropping as low as the temperature of the environment. "Waking up" from hibernation would require a very large amount of energy because it's very energy consuming to warm up such a big body. Bears have a lower surface/volume ratio and a sufficient amount of fur and fat insulation to withstand the cold, so there is no need to hibernate.

What differentiates brown fat from other fats?

Brown fat has a large cytoplasm packed full of mitochondria. The mitochondria in brown fat differ from other cells because there is no/little ATP synthase in the inner membrane, causing all/most energy to be lost as heat.

How does the nasal passageway preserve a camel's lung humidity?

Camels have a cooler, moist nasal passageway. When camels inhale warm, dry air it, moisture in the sinus evaporates humidifying & cooling the inhaled air. Because this air headed to lungs is now humidified, less water will evaporate from the lungs, conserving water. For lungs to function they need to remain moist. Hot dry air entering the lungs would dehydrate the lung tissue and it is too dry, lung function is compromised. Remember! a dry frog is a dead frog, dry air going into moist lungs would be bad.

How does a camel keep its brain cool?

Camels pump warm blood from their heart towards their brain, but this warm blood is cooled in a capillary bed (rete) with cool blood coming from the nasal passageway. This capillary bed can be closed off in the winter time (when necessary).

Which macromolecule is used for more "short-term" energy storage, and which macromolecule is used for more "long-term" energy storage?

Carbohydrates are used for short-term energy storage, lipids are used for long-term energy storage.

Name the 4 major macromolecules and the building blocks for each of them.

Carbohydrates: monosaccharides, proteins: amino acids, lipids: glycerol + fatty acid chains (for steroids, cholesterol), nucleic acids: nucleotides

What are codons? Why are triplet sequences necessary and what are their benefits?

Codons are triplets of mRNA nucleotides that code for specific amino acids. The triplet allows for four different nucleotides to code for around 20 amino acids: because there are more than 20 combinations of four bases, many amino acids can be coded for by different codons. This creates the benefit of "silent mutations" where often times, if the third nucleotide in a codon was transcribed incorrectly, the mutation is silenced because the tRNA still attaches the correct amino acid.

Give two reasons (not including flight!) for why dinosaurs may have developed feathers.

Dinosaurs may have developed feathers as a method for insulation, or as a result of mate choice, for adornment.

What is the importance of discovering intermediate forms in evolutionary biology?

Discovering intermediate forms allows scientists to complete accurate evolutionary branching patterns, and determine which species belong in which groupings.

What is endosymbiotic theory?

Endosymbiotic theory means "living together inside," and describes the transition from prokaryotes to eukaryotes. 2.7 billion years before evidence of the first eukaryotes, prokaryotes were found, and over time they began to vary and evolve, so that some were bigger than others, some became predators, and some became parasites. Endosymbiotic theory states that a prokaryotic parasite got inside a prokaryotic host. The two organisms lived in symbiosis (neutral/positive), but over time they co-evolved to depend on each other: this ultra positive (positive/positive) relationship is called mutualism. These specialized prokaryotic parasites ultimately formed what are now called organelles in eukaryotes.

Why are enzymes important in processes like molecule synthesis?

Enzymes are important in synthesis because they allow reactions to occur at a fast rate at a low specific heat. Without enzymes, it would take too much energy for a living system to have chemical reaxns for life.

What is estivation and what is it used for? (is it a good strategy?)

Estivation is the physical capacity to tolerate being overheated. It is used by creatures such as diurnal rodents- they go out during the day, they overheat (and their enzymes denature some), then they return to their burrow and try to cool down again, by increasing their surface to volume ratio and spreading out on cool soil. This is not a good solution to heat stress, but if you have to go out to forage it is making the best of a bad situation.

What allows eukaryotes to be bigger than prokaryotes?

Eukaryotes have a mitochondria which allows them to produce 30+ ATP/glucose molecule to fuel their actions. This allows eukaryotes to have specialized organelles and transport molecules throughout the cell. Prokaryotes rely solely on glycolysis in the cytoplasm, which only creates a net of 2 ATP, thus restricting their size and ability to remove waste (they rely on diffusion as a result).

What are the three types of lipids? Mention an example of each type and explain their function.

Fats/Oils/Waxes: Fat/oils -- source of energy; structure -- phospholipids are the major contributor to cell membranes; waxes can contribute water impermeability to outer layers of plants assisting in water conservation Steroids/Hormones: cholesterol, which serves a structural function in helping hold the phospholipid bilayer together and is a precursor to steroid production; regulatory: hormones regulate many metabolic/developmental processes.

Name two physical developments of early primates that resulted from their arboreal environment.

First, arboreal primates needed to leap from tree to tree to get food and escape predators. Because of this, their central nervous system developed to give them good hand-eye coordination and increased balance. Secondly, they developed leg specialization from their arboreal nature. Their hind legs needed to be muscled to give them leaping power, and their forelimbs needed to let them grasp and manipulate food, as well as catch tree branches (grip: both precision and power).

Dinosaurs may have developed feathers as a method for insulation, or as a result of mate choice, for adornment.

Fish and frogs (amphibians) have limbs that jut out to the side, since they need to use their limbs to propel themselves through water. Reptiles, as they became at least partially terrestrial need to hold up their bodies on land, so their limbs bend downwards. However, this was inefficient because they need to constantly expend energy and use muscle to hold themselves up. As mammals evolved, their limbs began to migrate to sit underneath them, not only allowing for a more efficient running structure, but allowing them to rest upright on their bones instead of always using muscles to hold themselves up.

Why is fortified wine higher in ethanol concentration?

Fortified wine has a higher ethanol concentration because more sugar is added towards the end, which is what yeast converts to ethanol and thus this generates a higher ethanol content.

How does gene flow increase homogeneity in a population?

Gene flow is the movement of genes into or out of a population due to the immigration and emigration of organisms. The more individuals move between subpopulations, the more likely differences in allele frequency between subpopulations will be minimized, rare alleles originating in a single subpopulation can disperse thru out the population, producing more homogenous distribution of types of alleles.

Why do we get goosebumps when we're cold or scared?

Getting goosebumps is a vestigial mechanism that are left from the times when human ancestors had a lot of fur. Piloerector muscles would make the guard hairs stand up to increase insulation when it's cold by trapping air in the underfur. Moreover, when in danger, piloerector muscles would make the hairs stand up to make the animal appear larger and therefore less likely to get attacked.

What is the traditional biological hierarchy/classification system?

Kingdom, Phylum, Class, Order, Family, Genus, Species

What is the standard definition of cute across cultures and why might this help evolutionary survival?

In general, we think something is cute when it has big eyes, a big head, and a small body: this aligns with what most infants look like. If our brain produces chemicals that make us feel good when we look at an infant, we will look at them more, potentially saving them from an accident. Thus, people who like to look at their cute children will pass on more of their genes just by virtue of them spending more time looking at their children. In addition, parents may want to have more babies once their current kids grow up and become less cute, again propagating the genes of parents that want to look at cute kids over ones that don't.

Why are savanna-based bipedals NOT prudent consumers?

In the low-density resource environment (savanna), they don't know when their next meal is, and if they do not consume everything in front of them, someone else may eat the food before they come back to it.

When does digestion happen for each macromolecule?

In the mouth, amylase digests carbs, the stomach proteases digest proteins, and the small intestine lipases digest lipids.

Why does drinking alcohol make you feel warm?

It causes vasodilation so blood flows to the periphery, making you feel heat on your skin. Although your skin detects heat (temp sensors), that result in letting more heat escape, and not preserving your core heat.

What physical properties of brown fat cells allow them to be used for heat production?

Like adipose tissue cells, brown fat cells are mainly composed of fat-containing vacuoles. However, brown cells differ in that 1) they contain more cytoplasm than adipose cells, and 2) that cytoplasm is packed with mitochondria. These mitochondria are unusual in that many have very few ATP synthase enzymes. This lack of ATP synthase in brown fat mitochondria allows those cells to be heat producers, because all the energy produced by H+ protons flowing down their concentration gradients within each mitochondrion during cellular respiration escapes as heat, instead of being harnessed to synthesize ATP.

Why do mammals have tooth occlussion?

Mammals have tooth occlussion because it allows them to better crush food without losing any food between the teeth.

Explain how mate choice is maladaptive. Explain what principles can make it adaptive.

Mate choice is sexual selection that can sometimes be maladaptive: for example, females may prefer to mate with males who take more risks, or who are brightly colored instead of camouflaged. Males who enter dangerous situations or who do not try and blend in do not necessarily have a higher reproductive rate as a whole, however it can be considered adaptive because the male takes a risk and still survives to mate- this is called the handicap principle.

If you go for a walk after eating a meal and start to feel chest pain, what are two ways you can test the possible cause for this pain and what would these tests reveal?

One: eat some food and drink some water. If the pain goes away, the cause was likely gastric reflux. Two: sit down and rest. If the pain goes away, the cause was likely cardiac and you should call a doctor!

Why is oxygen necessary in respiration?

Oxygen acts as the final acceptor of electrons from the transport chain. If it didn't take the e-, it would stay on the e-transport chain molecule and not be able to accept another--->e- transport chain would cease to function. Oxygen, after accepting an e- from the chain is highly reactive and forms water w/ free H+

Oxygen has a greater attraction for e- than H+. Why is this relevant for biology?

Oxygen's electronegativity gives special properties to water and allows for hydrogen bonding.

Name two more characteristics of early primates that resulted from their arboreal environment.

Primates were also vegetarian because of the availability of food in the forest. This coarse, plant-based diet necessitated large teeth to rupture cell walls, since primates cannot digest cellulose. Finally, primates were quadrupedal . Although this gives them low locomotor efficiency, they didn't have a need for high efficiency since there was plenty of food around (they didn't need to run long distances after prey).

What are the two factors that allowed descendants of amphibians to become fully terrestrial?

Reptiles developed the amniotic egg, an egg with a shell that does not permit water to enter or exit, but allows gas exchange of O2 and CO2. Because of this, the water in the egg is all the water the embryo receives during development. This caused a shift in how these creatures could deposit nitrogenous waste. Amphibians could afford to use highly-toxic, highly-soluble ammonia to get rid of their waste, because it could be kept dilute before beign passed into the water. However, reptiles couldn't do that because it would take water away from the developing embryo, and the toxicity could be potentially fatal to the egg. Thus, reptiles shifted to using low-soluble, low-toxicity uric acid for waste disposal (in a solid clump) away from the embryo in the egg.

What is the difference between a savanna and a grassland?

Savanna has occassional tree in otherwise flat grassland. Grassland is less likely to have a tree in it. Savanna is more a name for grasslands in the Eastern Hemisphere and grassland is more what is used in the Western Hemisphere.

How are whales and seals different (insulation-wise)?

Seals are smaller and have hair, whereas whales are huge, and have subdermal fat (blubber) instead of hair for insulation. This is because hair causes drag, which would immensely slow down a whale, because they have a much larger surface area of skin to cover.

How does the temporal order of the fossil record serve as evidence for evolution?

Temporal consistency is important because it shows modification with descent, a key feature of the theory of evolution. If scientists discover more advanced or varied forms of the same stem organism higher up in a stromatolite, they can conclude that these different species originated from one species and changed over time.

How do termites digest cellulose?

Termites have protozoans in their gut with bacteria inside. Those bacteria can make cellulase...so actually termites don't digest cellulose, their gut endosymbionts do. Termites benefit from the products of bacteria digestion of cellulose as bacteria and protozoans are "leaky" and some of those substance leak into the gut of termites.

More calorically dense foods in the savanna allowed for the development of what? What are the advantages and disadvantages?

The availability of high-fat foods like fruits, nuts, meat, and honey allowed for the development of a bigger cranium. A bigger brain is more costly to build and maintain, and requires mothers to have a high nutrient intake. IN addition, increased cranium size makes childbirth much more difficult.

How does population size affect the probability of stochastic extinction? What does this mean for the red pandas?

The bigger a population is, the less likely they are to become extinct by a chance event. In the case of the red pandas, scientists discovered that there were actually two different species of red panda, not one: this means that there are lower populations of each species, and thus each of the two species has a greater chance of becoming extinct (stochastically).

Why did humans evolve to have a lot of hair on their head and not anywhere else on the body?

The climate dried out, resulting in less forests and more grasslands. Without shade from the trees, being directly under the sun is too hot, so natural selection favors less body hair to avoid overheating. However, hair on the head is necessary to protect the brain from the heat and keep it cool.

What elements for the basic or key building blocks for life, and what makes carbon a good choice for supporting life?

The key building blocks for life are Carbon, Hydrogen, Oxygen, Nitrogen, and Phosphorus (CHONP). Carbon is a good choice for supporting life because it has four unpaired valence electrons, meaning that it can form up to four covalent bonds. It is also a highly flexible element since it is relatively small, and it can form many different chemical configurations (valence electrons not far apart-->flexibility in making double & triple bonds).

Two teen boys fall through the ice of a pond while playing hockey on a winter day and start to drown before being pulled out by a passerby. The boys are the same age but one is significantly larger than the other. Which of the two is likely to have suffered the most damage from the incident and why?

The larger fellow will likely suffer greater damage because his metabolic rate will take longer to drop (low S/V) and so his body will be performing anaerobic work for a longer period of time (since there is no oxygen available), which produces lactic acid and will start to hurt his body, while the smaller boy's metabolic rate drops much more quickly (high S/V), saving him from the harm caused by anaerobic respiration.

What makes mitochondrial production of ATP better/more efficient than manufacture in the cytoplasm?

The mitochondria has a double membrane with folds to maximize surface area for the electron transport chain. This transport chain pumps H+ out of the inner membrane to form a proton gradient. This allows for more efficient production of ATP, because H+ naturally wants to diffuse into the inner membrane, this concentration gradient allows for the production of 30+ ATP as the H+ passes thru the inner membrane through ATP synthase channels.

How did the old view regarding atherosclerosis differ from our more modern view on the process?

The old view attributed atherosclerosis to just sheer physical plaque build up on the interior surface of the coronary arteries blocking blood flow thru the lumen. The new view is that the plaque is within the inner lining of the artery, not in the lumen of the artery. In either case, the open diameter of the lumen is reduced. Now we know it is that the thickness of the lining increases by internal buildup of plaque.

How do camels conserve water lost through bodily respiration?

The snout preserves water loss on the exhale because exhaled air is approximately core temperature and saturated w/ water that evaporated from the lung surface. The snout is cooler that core temperature due to radiative heat loss. As warm moist air from the lungs passes thru the relatively cool snout the air is cooled. Cold air has a lower capacity for water vapor than warm air, so some water vapor condenses in the snout and is absorbed into the tissue and back into the circulatory system.

What is torpor and how does it aid small mammals?

Torpor is an overnight (short term) reduction in body temperature and it helps small mammals because it reduces energy required to keep body temperature up at night or during short-term cold snaps.

What makes water special?

Water has a neutral pH, it is known as the universal solvent because it dissolves the most substances of any liquid, the electronegativity of oxygen makes water a polar molecule, and water in its frozen form (ice) it is lighter because the polar molecules form a crystal lattice.

Why is water less dense in its frozen state than in its liquid state?

Water is less dense when it is a solid than a liquid because the hydrogen bonds are strong enough and the molecules are moving slow enough to hold the water molecules at a greater distance from each other, whereas in its liquid state the water molecules are gliding past each other, on average passing by closer than they are held apart as in ice.

Why is it extremely dangerous to inhale water?

Water moves against the salt gradient, so the water inhaled into our lungs will go on to enter our blood + cells of the lungs. Those lung cells will likely rupture and As our blood is pumped around our body, the water being carried from the lungs will enter various cells thru out the body, rupturing them. If enough cells in various organs rupture there could be massive organ failure.

Why do cells need to remove CO 2 from respiration?

When CO2 enters the blood it forms carbonic acid, which becomes harmful for organisms because it lowers pH.

Why is the curve for metabolic rate in endotherms asymmetrical?

When ambient temperature drops (looking on the left side of the metabolic rate curve), endotherms need to increase their metabolic rate in order to maintain a stable body temperature by replacing lost heat. When ambient temperature rises, (on the right side of the graph), endotherms need to fight two problems: they need to pump/dump heat back into the environment (need to do work to move heat against the gradient) AND dump the heat generated to do part one of the answer. This is what makes the curve asymmetrical, since endotherms cannot survive for as long while fighting two problems as ambient temperature gets hot.

What happens when ambient temperature gets so low in endotherms?

When ambient temperature gets so cold in endotherms, body temperature begins to drop faster than they can increase metabolic rate to replace heat. As body temperature drops, metabolic rate drops, this is called hypothermia.

Are savanna bipedals hairy? Explain.

While arboreal primates needed lots of hair as insulation, on the sunny savanna they do not need this insulation. Savanna bipedals thus evolved to have much less hair, opening up a high surface area for evaporative cooling. They retained head hair though to protect from the sun.

What allowed scientists to determine that whales are artiodactyls and not mesonychids?

While initially scientists lacked the evidence that they needed to label cetaceans as a subgroup of artiodactyls or mesonychids, the discovery of a whale ancestor with an ankle bone characteristic of current artiodactyls allowed them to complete the morphology and figure out that whales are artiodactyls.

Why can yeast convert pyruvate into ethanol and CO2 ? Why can't animals do the same?

Yeast has an enzyme that we do not have that allows them to convert pyruvate into ethanol. Due to the different biological tools available to them these organisms evolved to deal with anaerobic respiration differently.

What can we learn from a phylogenetic tree?

a phylogenic tree depicts the evolutionary pathways through which different species (and larger classification groups) appeared. Through this tree we can see evidence of modification with descent, or traits that help evolutionary success being passed down through the tree. We can also see which ancestors gave rise to which descendants, and how closely related two species are based on how far away (up the tree) their common ancestor is.

What does it mean when your body vasoconstricts in the periphery?

small arteries/capilaries are decreasing their diamter by constriction of muscles in artery walls in appendages/skin. With reduced blood the body is reducing the amount of warm blood flowing to parts of the body where surface area is high. This allows the body to retain more heat in the core because the blood isn't getting exposed to areas with such a high surface area.