π Darwin On the Origin of Species 1859 (11 MCQs)
π From Campbell Biology β’ 1. Evolution and the theme of Biology and Scientific Inquiry β’ 11 questions available
What is Darwin On the Origin of Species 1859?
Definition:
On the Origin of Species is Charles Darwin's seminal book published in 1859, which presented the scientific theory of evolution by natural selection, providing extensive evidence from comparative anatomy, embryology, biogeography, and the fossil record to argue that species are not fixed but have changed over time through descent with modification, and it revolutionized biological thought.
Working:
In this work, Darwin proposed that all species are connected by common ancestry and that natural selection acts on heritable variation, leading to gradual evolutionary change, and he introduced the concept of the tree of life" to represent branching evolutionary relationships and the accumulation of small changes over long periods can result in major adaptations with the rate of change often described by the equation known as the breeder's equation.
Example:
A simple example from the book is the comparison of homologous structures such as the forelimbs of mammals (human arm whale flipper bat wing) which have different functions but similar underlying bone structure demonstrating common descent and Darwin used this evidence to support his theory of evolution.
Reason:
This book is foundational to evolutionary biology because it provided a mechanism (natural selection) for evolutionary change challenged traditional views and stimulated extensive research and its principles remain the cornerstone of modern biology influencing genetics medicine and conservation."
π All Darwin On the Origin of Species 1859 MCQs
Q1. What was the central evolutionary mechanism emphasized by Darwin in On the Origin of Species?
π Explanation: Darwin proposed that populations contain heritable variation and that individuals with advantageous traits tend to survive and reproduce more successfully. Over generations, this differential reproductive success can change population characteristics and contribute to adaptation and divergence.
Q2. Why did Darwin's explanation represent a major conceptual shift in explaining biological diversity?
π Explanation: The major shift was viewing species as populations capable of changing through generations rather than as permanently fixed entities. Natural selection provided a population-level mechanism connecting inherited variation, environmental pressures, differential reproduction, and long-term biological change.
Q3. A beetle population contains green and brown individuals. Birds preferentially eat green beetles, while both colors reproduce normally when they survive. After many generations, what outcome would Darwin's reasoning most strongly predict?
π Explanation: If brown coloration is heritable, birds create a consistent survival difference between the two forms. Brown beetles therefore leave more descendants on average. Across many generations, this differential reproductive success can increase the frequency of brown coloration in the population.
Q4. A student argues, 'Giraffes developed longer necks because individual giraffes repeatedly stretched to reach leaves, and their offspring inherited the longer neck.' Which criticism best reflects Darwinian reasoning?
π Explanation: The student's reasoning confuses individual modification with population-level evolutionary change. Darwin's framework begins with existing heritable variation. If longer necks improve feeding success and are inherited, individuals possessing them may reproduce more successfully, changing population composition over generations.
Q5. Researchers observe that a bird population contains beaks of several shapes. During a drought, hard seeds become common, and birds with deeper beaks produce more surviving offspring. Which conclusion is most consistent with Darwin's reasoning?
π Explanation: The key reasoning involves three steps: variation exists, the environment changes reproductive success, and the relevant trait is heritable. If deeper-beaked birds consistently leave more surviving offspring, their inherited beak characteristics can become more frequent in subsequent generations.
Q6. A population's average body size changes after several generations, but researchers find that body size has very low heritability. A student concludes that natural selection must have caused the change. What is the strongest objection?
π Explanation: A population average can change because of environmental effects, migration, random processes, or selection. For natural selection to produce a persistent evolutionary response, differences associated with reproductive success must involve heritable variation. Therefore, the observed average change alone is insufficient evidence.
Q7. A graph shows the frequency of a dark-wing phenotype rising from 20% to 65% over eight generations in a population exposed to predators. Which additional observation would most strongly support natural selection as the explanation?
π Explanation: The graph establishes a population change but not its cause. Evidence that dark-wing individuals consistently leave more offspring connects the phenotype to differential reproductive success, while inheritance connects that difference to evolutionary change across generations. Together, these observations strongly support selection.
Q8. Suppose two isolated populations experience different environments. Population X favors individuals with thicker fur, whereas Population Y favors thinner fur. If fur thickness varies heritably in both populations, what long-term pattern would Darwin's framework predict?
π Explanation: Different environments can impose different survival and reproductive pressures. If fur thickness is heritable, selection can favor different variants in the two isolated populations. Over many generations, the populations may therefore diverge in trait frequencies and potentially accumulate broader differences.
Q9. Which statement best distinguishes natural selection from an individual's ability to adjust to environmental conditions during its lifetime?
π Explanation: An individual may adjust physiologically or behaviorally during its lifetime without that adjustment becoming an inherited population trait. Natural selection instead concerns differences in survival and reproduction associated with heritable variation, producing changes in trait frequencies across generations.
Q10. A student claims, 'If an environmental challenge is severe enough, natural selection will always produce a perfect adaptation.' Which assumption in this statement is most problematic?
π Explanation: Natural selection does not design organisms according to future needs. It acts on existing heritable variation, and advantageous traits may involve costs or trade-offs. Consequently, selection can improve adaptation under particular conditions without guaranteeing perfection or anticipating future environmental changes.
Q11. A researcher compares two populations and finds that Population A has greater variation in a trait, but Population B has stronger differences in reproductive success associated with that trait. Which population could experience the stronger response to natural selection, assuming heritability is comparable?
π Explanation: Variation alone does not determine the strength of evolutionary change. Natural selection requires differential reproductive success associated with heritable differences. If heritability is similar, stronger reproductive differences in Population B can generate a stronger selection pressure, even though Population A has greater raw variation.