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A student says, "Mutations always help an organism survive." Do you agree? Explain.
No. Mutations are random and can be beneficial, harmful, or have no effect. Whether a mutation is helpful depends on the environment.
A skull has sharp canine teeth and forward-facing eyes. What can you infer about this animal's lifestyle?
It was likely a predator or carnivore because these features help capture prey and judge distance.
A rabbit population grows rapidly after being introduced to an island with abundant food and no predators. Why does the population grow so quickly at first?
The rabbits experience exponential growth because resources are plentiful and there are few limiting factors.
A person accidentally cuts their finger while cooking. Which blood component immediately helps prevent excessive blood loss?
Platelets begin forming a clot to reduce bleeding.
During the sheep eye dissection, the lens accidentally fell out of the eye. Based on its function, what problem would this cause if it happened in a living animal?
The animal would have difficulty focusing light onto the retina, causing blurry vision because the lens helps focus incoming light.
Two populations of the same species become separated by a river. Years later, scientists notice that each population has different allele frequencies. Name two evolutionary mechanisms that could explain these differences.
Any two: mutation, natural selection, genetic drift, or gene flow (if individuals occasionally crossed the river). Each changes allele frequencies in different ways.
A student groups dolphins and sharks together because they both have streamlined bodies and fins. Explain why this may not accurately represent their evolutionary relationship.
Similar body shapes can result from convergent evolution. Scientists would rely on homologous structures or DNA evidence rather than appearance alone.
A student says, "A population can keep growing forever as long as animals continue reproducing." Explain why this statement is incorrect.
No population can grow forever because resources eventually become limited. Populations eventually reach carrying capacity.
A patient's lungs are healthy, but they have very few red blood cells. Why might they still feel tired during exercise?
They have fewer red blood cells and less hemoglobin to carry oxygen to their muscles.
During the blind spot activity, students noticed that an object disappeared when one eye was closed and the paper was held at a certain distance. Explain why this happened.
The image landed on the optic disc (blind spot), where there are no photoreceptors. Since no light is detected there, the object temporarily disappears.
A few birds from Population A begin nesting with Population B every spring. Over time, the two populations become more genetically similar. Explain why.
Gene flow occurs because individuals move between populations and reproduce. This introduces alleles into the new population and makes the populations more genetically similar.
Scientists compare the forelimbs of humans, whales, bats, and cats. Although the limbs perform different functions, they all share similar bone arrangements. What conclusion can be made?
These are homologous structures, suggesting the organisms share a common ancestor.
Two forests are the same size, but one supports twice as many deer as the other. Explain one reason why.
The forest with more food, water, shelter, or other resources has a higher carrying capacity and can support more deer.
During the sheep heart dissection, you noticed that the left ventricle had much thicker walls than the right ventricle. Explain why.
The left ventricle pumps blood throughout the entire body, so it must generate much greater force than the right ventricle, which only pumps blood to the lungs.
A student says, "The retina sends light to the brain." Evaluate this statement and explain the correct process.
The statement is incorrect. The retina detects light and converts it into nerve impulses, which are then carried to the brain by the optic nerve.
A disease randomly kills 80% of a population. One student says this is natural selection. Another says it's genetic drift. Who is more likely correct? Explain.
The student who says genetic drift is more likely correct if survival was random. Since individuals were not selected because of advantageous traits, the event is a bottleneck effect.
Why do scientists use phylogenetic trees instead of simply comparing how organisms look?
Phylogenetic trees show evolutionary relationships based on shared ancestry, often using genetic and anatomical evidence rather than appearance alone.
A disease spreads through a crowded deer population but has little effect when the population is small. Explain why.
Disease is density-dependent because it spreads more easily when individuals are living close together.
A blood clot blocks the pulmonary artery. Which organ would receive less blood, and why?
The lungs would receive less blood because the pulmonary artery carries deoxygenated blood from the heart to the lungs for gas exchange.
During the two-point discrimination lab, your fingertips could distinguish two points much better than your forearm. Explain why.
Fingertips contain a much higher density of sensory receptors, allowing them to detect two closely spaced points more accurately than areas with fewer receptors.
Two isolated populations of salamanders experience different mutations, different environments, and different selective pressures over thousands of years. Explain why scientists might eventually classify them as different species.
Over time, the populations may become reproductively isolated and unable to produce fertile offspring. Once this occurs, they are considered different species through speciation.
Two species look almost identical, but DNA evidence shows they are only distantly related. Explain why DNA is considered stronger evidence than appearance.
Appearance can evolve independently through convergent evolution, while DNA more accurately reflects inherited evolutionary relationships.
After several years of rapid growth, a fish population begins leveling off even though no fishing has occurred. Explain what is happening.
The population is approaching carrying capacity because limiting factors such as food, oxygen, or space are preventing continued rapid growth.
Two patients have healthy lungs. One has a hematocrit of 46%, while the other has a hematocrit of 22%. Which patient would likely transport oxygen more efficiently? Explain your reasoning.
The patient with a hematocrit of 46% would transport oxygen more efficiently because they have a higher percentage of red blood cells containing hemoglobin.
A patient has healthy eyes, but damage to the optic nerve. Explain how this would affect vision and why.
The eyes could still detect light, but visual information could not be transmitted to the brain. As a result, vision would be greatly impaired or lost because the optic nerve carries signals from the retina to the brain.