BIG BANG & COSMIC EVIDENCE
A student says, “If distant galaxies are moving away from us, their light should be stretched to longer wavelengths.” This observation is exactly what astronomers see and use as key evidence for the Big Bang.
What is redshift?
These stars, including the Sun, are all in a long, stable stage of their lives where they fuse hydrogen into helium in their cores.
What are main sequence stars?
The era during which the first cells evolved has this name.
What is the Precambrian?
The idea that the first life arose from nonliving chemistry in Earth’s early oceans, not from already-living organisms, has this name.
What is abiogenesis?
Small streams flow together to form larger ones, and the whole network drains an area of land. The small streams that feed into a larger river are called this.
What are tributaries?
As the early solar nebula collapsed and spun faster, most of the mass collected in the center to form the Sun, while the rest flattened into a disk. Using this model, explain why rocky planets ended up close to the Sun and gas/ice giants formed farther away.
What is “Because the Nebular Hypothesis says the inner solar system was too hot for ices to condense, only metals and rock could form solid planets near the Sun, while farther out beyond the frost line, ices could condense and grow into larger gas and ice giants”?
Two stars have the same temperature, but one is much brighter. On the HR diagram, the brighter star is high above the main sequence and has a large radius. This type of star is most likely this kind.
What is a giant (or supergiant) star?
A student timeline shows: “Fish appear, dinosaurs dominate, mammals diversify, humans evolve.” The extinction event that separates the dinosaur-dominated time from the mammal-dominated time happened at about 66 million years ago and is known for being triggered by this cause.
What is an asteroid impact?
Cyanobacteria changed Earth’s oceans and atmosphere by doing this process, which eventually led to the Great Oxygenation Event.
What is photosynthesis (releasing oxygen)?
As a river flows from steep mountains to flatter land, it changes from mostly cutting into rock to mostly dropping off sediment. Name the process that wears rock away, and the process that builds new features like deltas.
What are weathering (wearing away) and deposition (building up)?
Most of the normal matter in the universe is hydrogen and helium, not heavier elements. This fact supports the idea that the early universe was extremely hot and dense and then cooled as it expanded. This idea about how the universe began is called this.
What is the Big Bang Theory?
Inside a main-sequence star, hydrogen nuclei join to form helium. The helium has slightly less mass than the original hydrogen. The “missing” mass appears as this, which escapes and powers the star.
What is energy (released as light and heat), from nuclear fusion?
You are given four events:
Cambrian Explosion
Great Oxygenation Event
Dinosaur extinction
First multicellular life
Two of these belong in the Precambrian. Name both.
What are the Great Oxygenation Event and the first multicellular life?
Theory says that early eukaryotic cells formed when one cell took in another cell that then lived inside and kept working. This explanation for mitochondria and chloroplasts is known as this.
What is endosymbiosis (the endosymbiotic theory)?
A class is asked to find one example of weathering, one of erosion, and one of deposition along a river. You see:
– “Sandbar forming near the inside of a bend”
– “Broken rock on a cliff face”
– “Sediment carried in muddy water”
Match each to weathering, erosion, or deposition.
Sandbar forming = deposition
broken rock on cliff = weathering
muddy water carrying sediment = erosion.
A student claims, “Because Earth is about 4.6 billion years old, the universe must be the same age.” Use what you know about radioactive dating and cosmic evidence to correct the claim: this is the approximate age scientists give for the entire universe.
What is about 13.8 billion years?
A low- or medium-mass star like the Sun eventually swells into a red giant, loses its outer layers, and leaves behind a hot, dense core. The glowing shell of gas and the tiny core have these two names.
What are a planetary nebula and a white dwarf?
Someone says, “Life got complex all at once during the Cambrian, so nothing important happened before that.” Use your knowledge of Earth history to name one major biological change that happened before the Cambrian Explosion and helped make it possible.
What is the rise of oxygen from cyanobacteria / the Great Oxygenation Event
the evolution of eukaryotes
or the evolution of multicellularity?
Explain why sexual reproduction sped up evolution compared to asexual reproduction. Name one specific reason, based on how genes are combined.
What is that sexual reproduction increases genetic variation (through mixing of genes from two parents, crossing over, etc.), giving natural selection more variety to act on?
A dam is built across a river to create a deep water body used for drinking water and electricity. Compare this new feature to a natural lake: what is the human-made feature called, and what main process created it?
What is a reservoir, created by damming (blocking) a river?
In a debate, one person argues that “the Big Bang can’t be real, because we still see radiation everywhere in space.” Another says, “That is exactly what we expect if the universe started hot and has been cooling.” The faint glow they’re arguing about has this specific name.
What is the cosmic microwave background (CMB)?
Your body contains carbon, oxygen, iron, and many other elements heavier than helium. These elements were built in massive stars and then blasted out into space during this violent stage of a high-mass star’s life.
What is a supernova?
A student draws a timeline where humans appear immediately after the dinosaurs go extinct, with almost nothing in between. Use the names of at least two eras to correct this: after dinosaurs went extinct at the end of the Mesozoic, most of the time before humans is in this later era (__________), during which mammals did this (____________).
What is the Cenozoic Era, during which mammals diversified (radiated into many forms)?
Amphibians and reptiles both live on land, but they do not play the same role in Earth’s story. One of these groups remained tied to water for reproduction and moist skin, while the other evolved traits like shelled eggs and tougher skin. Name which group gained those traits, and explain how that change affected where animals could live.
What are reptiles, and they could live fully on dry land and spread into drier environments because their eggs and skin resisted drying out?
A student argues that “rivers are only important locally; they don’t really matter to Earth systems.” Use at least two of the following ideas to argue against that: weathering, erosion, deposition, sediment delivery to the ocean, or habitat creation.
Any answer that explains that rivers weather rock, erode and move sediment, deposit it in floodplains and deltas, feed sediment and nutrients to oceans, and create habitats along their paths.