Earth, Moon, and Sun Key Concepts
Explain why the Moon appears to shine even though it does not make its own light.
The Sun illuminates the Moon; sunlight reflects off the Moon’s surface, so we see it shine.
Give the term for the Moon phase when we see almost none of the illuminated side.
New moon.
State what determines whether a trait is adaptive or not.
Whether a trait is adaptive depends on the environment and whether it increases survival or reproduction in that environment.
State how shared body structures between two species provide evidence about their relationship.
Shared structures suggest inheritance from a common ancestor; similar anatomy indicates relatedness.
What is an adaptive trait? Provide a brief example.
An adaptive trait increases an organism’s chance to survive or reproduce in a given environment (e.g., camouflage coloration).
Define what “to scale” means for a model and give one reason some models are intentionally “not to scale.”
“To scale” means relative sizes/distances are proportionally accurate; some models are not to scale because real distances would be impractical or too large to represent (e.g., sun–earth distance).
Name the Moon phase when the entire near side is illuminated.
Full moon.
Describe how the number of individuals with a specific trait in a population can change over time.
Through adaptive traits allowing survival and reproduction: individuals with adaptive traits leave more offspring, increasing trait frequency; others decline.
Explain speciation in simple terms and name one factor that can cause populations to diverge.
Speciation is the formation of new species from one ancestral population, often caused by geographic separation, different selection pressures, or genetic divergence.
What is a histogram and how might one be used to show variation in a trait across a population?
A histogram is a bar graph showing frequency distribution of a trait (e.g., beak size); it reveals variation and common trait values.
Describe how the positions of the Sun, Earth, and Moon produce the phases of the Moon as seen from Earth.
The Sun lights half the Moon; as the Moon orbits Earth we see changing portions of that lit half, producing phases from new → crescent → quarter → gibbous → full and back.
What is the term for a Moon phase that is more than half lit but not full?
Gibbous moon.
Explain the role of mutations in generating new traits and how a new trait can increase in frequency.
Mutations change genes and sometimes traits; if a mutation produces an advantageous trait, natural selection can increase its frequency over generations.
Describe how small changes over long time can produce major differences in body structures between descendant species.
Small heritable changes accumulate across many generations; over long timescales these changes can lead to major anatomical differences between species.
Define “offspring” in biological terms and explain why offspring are important for natural selection.
Offspring are the young produced by parents; they carry genes and allow traits to be passed to next generations, enabling natural selection.
Explain why lunar eclipses only occur when Earth is between the Sun and the Moon, and why they do not happen every month.
Lunar eclipses occur only at full moon when Earth is between Sun and Moon; they don’t happen every month because the Moon’s orbit is tilted relative to Earth’s orbit, so alignment is not exact each month.
Define “terminator” in the context of the Moon and explain its significance for phases.
The terminator is the line separating lunar day and night; it marks the boundary between illuminated and dark regions and determines the visible phase.
Suppose a population of insects is exposed to a pesticide. Describe the sequence of events, over many generations, that could lead to pesticide resistance becoming common.
Pesticide kills susceptible insects; resistant individuals (via mutation or existing variation) survive and reproduce; with repeated exposure, resistant trait frequency increases, leading to a resistant population.
You are given fossils of three species. Explain how you would decide which two are most closely related using shared structures.
Compare shared derived structures: the two species sharing more unique structures with each other than with the third are most closely related.
Free points!
Free points!
Explain the difference between “orbit” and “rotation” for the Moon, and how each affects what we observe from Earth.
Orbit is the Moon’s path around Earth; rotation is the Moon spinning on its axis. The Moon’s synchronous rotation means the same face points toward Earth, so orbit changes our viewing angle while rotation keeps the same near side facing us.
Explain how protein molecules link genes to observable traits.
Genes code for proteins; proteins build body structures and carry out functions that produce observable traits.
Explain why body structures may stay stable in some lineages but change in others, linking your answer to environmental stability and natural selection.
If the environment stays stable, selection favors existing successful structures (stability); changing environments alter selective pressures, producing structural change via natural selection.
Define “common ancestor population” and give a short example.
A common ancestor population is an ancestral group from which two descendant species share inherited traits.