Evolution (C736)

Explanation:

Convergent evolution occurs when unrelated species independently evolve similar traits because they face similar environmental pressures or ecological niches. The resemblance is not due to shared ancestry but to adaptations that provide similar functional advantages. Examples include the wings of bats and birds or the streamlined bodies of dolphins and sharks.

Correct Answer:

Convergent evolution

Why Other Options Are Wrong:

Directional selection

Directional selection is a type of natural selection that favors one extreme of a trait in a population. While it can drive adaptation, it does not explain similar traits evolving in unrelated species.

Divergent evolution

Divergent evolution occurs when related species evolve different traits over time, increasing their differences rather than producing similarities.

Adaptive radiation

Adaptive radiation involves rapid diversification of a single ancestral species into multiple forms to exploit different ecological niches. It describes diversification, not independent convergence of unrelated species.

Biogeography

Biogeography is the study of the geographic distribution of species and ecosystems. It does not describe the evolutionary process leading to similar traits in unrelated species.

Explanation:

Lamarck proposed that traits acquired or modified during an organism’s lifetime could be inherited by its offspring. For example, if an organism developed a trait due to environmental pressures or behavior, that trait could be transmitted to the next generation. This concept, known as the inheritance of acquired characteristics, contrasts with Darwinian natural selection, which relies on heritable genetic variation rather than traits developed during an organism’s lifetime.

Correct Answer:

Lamarck proposed that organisms could pass on traits acquired during their lifetime to their offspring.

Why Other Options Are Wrong:

Lamarck argued that environmental changes do not affect organisms.

This is incorrect because Lamarck’s theory explicitly connected environmental changes and organismal behavior to the development of new traits. Environmental influence was central to his explanation.

Lamarck believed that natural selection was the primary driver of evolution.

Darwin, not Lamarck, formulated natural selection. Lamarck focused on acquired traits, so this option misrepresents his theory.

Lamarck suggested that all species are fixed and do not change over time.

Lamarck argued that species could change over time through acquired traits. Claiming species are fixed contradicts his main concept, making this option incorrect.

Explanation:

All of the listed items provide evidence for evolution. The molecular record, including DNA and protein sequences, reveals genetic similarities and differences reflecting shared ancestry. Homologous structures indicate common evolutionary origins through similar anatomical features. The fossil record documents species that lived in the past and transitional forms, showing evolutionary changes over time. Analogous structures, while arising from convergent evolution, provide evidence of how similar selective pressures can shape unrelated species. Together, these lines of evidence support the theory of evolution.

Correct Answer:

all of the answer choices are correct

Why Other Options Are Wrong:

the molecular record

While molecular evidence strongly supports evolution, it alone does not include anatomical or fossil data, so it is incomplete.

homologous structures

Homologous structures demonstrate common ancestry, but other forms of evidence such as molecular data and fossils are also necessary to provide a complete evolutionary picture.

The fossil record

The fossil record shows historical species and transitions, but it does not account for genetic or anatomical evidence, so it alone is insufficient.

analogous structures

Analogous structures illustrate functional similarities due to convergent evolution rather than common ancestry. While informative, they do not alone provide a comprehensive body of evidence for evolution.

Explanation:

Directional selection occurs when environmental pressures favor one extreme phenotype over others, leading to a shift in the population’s traits over time. In the case of Kauai crickets, parasitism by flies that locate males by their chirping favored silent males. Over time, the frequency of the silent trait increased in the population, demonstrating directional selection toward the extreme phenotype of silence.

Correct Answer:

Directional selection

Why Other Options Are Wrong:

Disruptive selection

Disruptive selection favors individuals at both extremes of a trait and can lead to a bimodal distribution. In this scenario, only one extreme—silence—is favored, so disruptive selection does not apply.

Stabilizing selection

Stabilizing selection favors intermediate traits and reduces extremes. Since the cricket population is shifting toward one extreme (silence), stabilizing selection is incorrect.

Sexual selection

Sexual selection favors traits that increase mating success. Although cricket chirping is involved in mating, the selection here is driven by predation pressure from flies, not female mate choice, so sexual selection is not the primary factor.

Explanation:

In an experiment, the independent variable is the factor that is deliberately manipulated to observe its effect on a dependent variable. In this case, testing the effect of a new predator involves changing whether or not the predator is present. This manipulation allows researchers to determine how the woodpigeons respond to the predator, making the presence of the predator the independent variable.

Correct Answer:

The presence of the new predator

Why Other Options Are Wrong:

The woodpigeon's nesting habits

Nesting habits are characteristics of the pigeons and could be influenced by experimental conditions, making them a dependent variable, not the independent variable.

The weather conditions during the experiment

Weather is an external factor and would typically be considered a control variable if kept constant. It is not deliberately manipulated in this experiment, so it is not the independent variable.

The availability of food for the woodpigeon

Food availability could influence woodpigeon behavior but is not the factor being tested in this scenario. Therefore, it is not the independent variable.

Explanation:

Descriptive science is the branch of science that focuses on observing, describing, and collecting data about natural phenomena without testing a specific hypothesis. It involves detailed measurements, observations, and documentation to establish patterns, relationships, or general information about a subject. This type of science lays the groundwork for forming hypotheses and conducting experimental research later but does not involve manipulating variables to test predictions.

Correct Answer:

Descriptive science

Why Other Options Are Wrong:

Theoretical science

Theoretical science involves developing models, simulations, or frameworks to explain phenomena, often using mathematics or logic. It is not focused on data collection without a hypothesis, making it an incorrect choice for this question.

Experimental science

Experimental science tests specific hypotheses by manipulating variables and observing outcomes. Since descriptive science does not involve hypothesis testing, experimental science does not match the description in the question.

Applied science

Applied science uses scientific knowledge to solve practical problems or develop technologies. While applied science may use descriptive or experimental data, its primary focus is on application rather than collecting data without forming a hypothesis.

Explanation:

A hypothesis is a tentative explanation for an observation that can be tested through experimentation or further investigation. When a biologist proposes a theory without experimental support, it is considered a hypothesis because it has not yet been empirically verified. This classification allows scientists to design experiments to confirm or refute the proposed idea.

Correct Answer:

As a hypothesis

Why Other Options Are Wrong:

As a fact

A fact is an observation that has been repeatedly confirmed and is generally accepted as true. A proposed theory without experimental evidence cannot be considered a fact, making this option incorrect.

As a conjecture

Conjecture implies speculation without a basis for testing. Scientific hypotheses, even untested ones, are grounded in observation and are structured to allow empirical testing, so “conjecture” is not the proper classification.

As a scientific law

A scientific law describes a consistently observed natural phenomenon, often expressed mathematically, and is universally accepted. A theory without experimental support cannot be classified as a law, making this option incorrect.

Explanation:

Macroevolution refers to large-scale evolutionary changes that occur over long time periods, leading to the formation of new species and higher taxonomic groups. It encompasses processes such as speciation, adaptive radiation, and major morphological changes. Unlike microevolution, which involves small changes within populations, macroevolution describes the broad patterns of evolution responsible for the diversity of life.

Correct Answer:

macroevolution

Why Other Options Are Wrong:

vertical descent

Vertical descent refers to the transmission of genetic material from parent to offspring, which is a mode of inheritance rather than a process that directly defines the formation of new species.

microevolution

Microevolution involves small changes in allele frequencies within populations. While it contributes to evolutionary change, it does not typically account for the large-scale changes that produce new species.

horizontal gene transfer

Horizontal gene transfer is the movement of genetic material between unrelated organisms, common in bacteria. While it can influence evolution, it is not the main process leading to speciation in most multicellular organisms.

natural selection

Natural selection is a mechanism of evolution that acts on variation within populations. While it can drive evolutionary change, it is not synonymous with macroevolution, which specifically refers to the formation of new species and higher-level taxa.

Explanation:

Organisms in the domain Eukarya are defined by having complex cells with membrane-bound organelles, including a true nucleus that contains their genetic material. This domain includes both unicellular and multicellular organisms. Specifically, the kingdom Plantae within Eukarya consists of multicellular, photosynthetic organisms that produce their own food through photosynthesis. These organisms have specialized structures such as cell walls made of cellulose and chloroplasts, which distinguish them from other eukaryotes.

Correct Answer:

Organisms in the domain Eukarya have complex cells with a nucleus and include multicellular organisms like plants.

Why Other Options Are Wrong:

Organisms in the domain Eukarya are exclusively prokaryotic

This is incorrect because prokaryotic organisms belong to the domains Bacteria and Archaea, not Eukarya. Eukaryotes have complex cells with a nucleus.

Organisms in the domain Eukarya are unicellular and lack a nucleus

While some eukaryotes are unicellular, they always have a nucleus. Lacking a nucleus is a characteristic of prokaryotes, not Eukarya.

Organisms in the domain Eukarya are only found in aquatic environments

Eukaryotes are found in a wide range of habitats, including terrestrial and aquatic environments. This statement is too restrictive and inaccurate.