Unit Test: Origins of the Universe and Earth

Question 1

Use the star data table below to answer Questions 1–4.

| Star       | Mass (× Sun) | Surface Temp (K) | Color          | Estimated Lifespan       | Elements Detected in Spectrum          |
|------------|--------------|------------------|----------------|--------------------------|----------------------------------------|
| Proxima C  | 0.12         | 3,050            | Red            | ~4 trillion years        | Hydrogen, Helium                       |
| Sun        | 1.00         | 5,778            | Yellow-White   | ~10 billion years        | Hydrogen, Helium, Carbon               |
| Sirius A   | 2.10         | 9,940            | Blue-White     | ~1 billion years         | Hydrogen, Helium, Carbon, Oxygen       |
| Betelgeuse | 11.60        | 3,500            | Red-Orange     | ~10 million years (near end) | Hydrogen, Helium, Carbon, Oxygen, Iron |

Based on the data table, which star will have the SHORTEST lifespan?

Accepted Answer

Betelgeuse, because its high mass causes it to burn fuel faster

Question 2

Use the star data table from Question 1 to answer this question.

A student claims: 'Betelgeuse has heavier elements in its core because it is a red star, and red stars always contain heavier elements.' Which statement BEST explains why this claim is incorrect?

Accepted Answer

Betelgeuse's high mass allows fusion to continue further, producing heavier elements regardless of color

Question 3

Use the star data table from Question 1 to answer this question.

According to the data, which TWO stars are most likely to end their lives as a supernova and scatter heavy elements into space?

Accepted Answer

Sirius A and Betelgeuse, because their high masses allow fusion to produce heavier elements

Question 4

Use the star data table from Question 1 to answer this question.

A scientist wants to find the OLDEST stars in the universe in order to estimate a minimum age for the universe. Based on the data and the unit's content, which type of star should the scientist look for, and why?

Accepted Answer

Low-mass red stars like Proxima C, because they burn fuel slowly and can survive for trillions of years

Question 5

Which sequence CORRECTLY describes the order of events from the Big Bang to the formation of Earth, as described in the unit?

Accepted Answer

Big Bang → hydrogen and helium form → stars form → nuclear fusion creates heavy elements → solar system and Earth form

Question 6

A student observes a car race. As a car speeds toward the student, the engine sounds high-pitched. As the car passes and moves away, the sound drops to a lower pitch. A scientist uses this same principle to study galaxies. Which phenomenon does this BEST model?

Accepted Answer

The Doppler Effect and redshift, because light from galaxies moving away is stretched to longer wavelengths

Question 7

Scientists use the model-prediction-evidence framework to support the Big Bang Theory. Which statement BEST describes how Cosmic Microwave Background Radiation (CMBR) fits this framework?

Accepted Answer

CMBR is the evidence; the Big Bang model predicted leftover energy should exist, and scientists later detected faint microwave radiation in every direction in space

Question 8

The universe is currently about 74% hydrogen and 24% helium by mass. How does this observation support the Big Bang Theory?

Accepted Answer

It matches the Big Bang model's prediction that the early universe formed mostly simple elements, with heavier elements created later in stars

Question 9

Use the galaxy recession data table below to answer Questions 9–12.

| Galaxy     | Distance from Earth (Mly) | Recession Speed (km/s) | Redshift Magnitude |
|------------|--------------------------|------------------------|--------------------|
| Andromeda  | 2.5                      | −110 (approaching)     | Blueshift          |
| Virgo      | 54                       | 1,180                  | Low                |
| Coma       | 321                      | 6,925                  | Moderate           |
| Hydra      | 840                      | 18,000                 | High               |
| Boötes     | 2,500                    | 39,000                 | Very High          |

Based on the data table, which statement BEST describes the relationship between a galaxy's distance from Earth and its recession speed?

Accepted Answer

Galaxies that are farther from Earth tend to move away at greater speeds than closer galaxies

Question 10

Use the galaxy recession data table from Question 9 to answer this question.

Notice that Andromeda shows a blueshift instead of a redshift. What does this tell scientists about Andromeda?

Accepted Answer

Andromeda is moving toward Earth, so its light waves are compressed to shorter (bluer) wavelengths

Question 11

Use the galaxy recession data table from Question 9 to answer this question.

A student argues: 'The data shows that Earth is at the center of the universe because all galaxies (except Andromeda) are moving away from us.' Which reasoning BEST explains why this conclusion is flawed?

Accepted Answer

Space itself is expanding in all directions, so every point in the universe sees other galaxies moving away — no single location is the center

Question 12

Use the galaxy recession data table from Question 9 to answer this question.

If scientists could reverse the expansion of the universe shown in the data — running it backward in time — what conclusion would they most likely reach?

Accepted Answer

In the distant past, all galaxies were much closer together, suggesting the universe began from a single hot, dense state

Question 13

Use the Earth age evidence table below to answer Questions 13–15.

| Evidence Type           | Sample / Source              | Estimated Age         | Method Used              |
|-------------------------|------------------------------|-----------------------|---------------------------|
| Oldest Earth rock       | Jack Hills, Australia        | ~4.0 billion years    | Radiometric (Uranium-Lead)|
| Oldest Earth mineral    | Zircon crystal, Australia    | ~4.4 billion years    | Radiometric (Uranium-Lead)|
| Canyon Diablo Meteorite | Iron meteorite, Arizona      | ~4.54 billion years   | Radiometric (Lead-Lead)   |
| Allende Meteorite       | Carbonaceous chondrite       | ~4.56 billion years   | Radiometric (Aluminum-Magnesium) |
| Moon rocks (Apollo)     | Lunar highlands              | ~4.5 billion years    | Radiometric (multiple)    |

A student notices that the oldest Earth rocks (4.0 billion years) are younger than the oldest meteorites (4.56 billion years). Which explanation BEST accounts for this difference?

Accepted Answer

Earth's surface has been continuously recycled through geological processes, destroying evidence of its earliest rocks

Question 14

Use the Earth age evidence table from Question 13 to answer this question.

Which TWO pieces of evidence from the table provide the STRONGEST support for estimating Earth's age at approximately 4.5 billion years?

Accepted Answer

The Canyon Diablo Meteorite and Moon rocks, because they formed from early solar system material and are unaffected by Earth's geological recycling

Question 15

Use the Earth age evidence table from Question 13 to answer this question.

[FIGURE: Diagram showing the CER (Claim-Evidence-Reasoning) framework as three connected boxes. Box 1 labeled 'CLAIM' contains: 'Earth is approximately 4.5 billion years old.' Box 2 labeled 'EVIDENCE' is blank. Box 3 labeled 'REASONING' contains: 'Meteorites and Moon rocks formed from early solar system material and were not recycled by Earth's geological processes, so they preserve the original age of the solar system.']

Using the data table and the CER diagram, which statement BEST completes the EVIDENCE box?

Accepted Answer

Radiometric dating of meteorites like Canyon Diablo (~4.54 Bya) and Moon rocks (~4.5 Bya) consistently yield ages near 4.5 billion years

Question 16

A class collected redshift and distance data from four distant galaxies. Use the data table below to answer the question.

| Galaxy | Distance from Earth (million light-years) | Redshift Value (z) | Interpretation |
|--------|-------------------------------------------|--------------------|----------------|
| A      | 250                                       | 0.018              | Moving away slowly |
| B      | 500                                       | 0.036              | Moving away moderately |
| C      | 1,000                                     | 0.072              | Moving away faster |
| D      | 2,000                                     | 0.144              | Moving away very fast |

(1) Describe the pattern you see between distance and redshift value. (2) Explain what this pattern tells us about the universe, and (3) identify which piece of Big Bang evidence this data best supports — Redshift/Hubble's Law, Cosmic Microwave Background Radiation, or Composition of Matter — and explain WHY it supports the Big Bang model rather than contradicting it.

Accepted Answer

Pattern: As the distance from Earth increases, the redshift value also increases. Galaxies that are farther away have higher redshift values, meaning they are moving away from us faster. This pattern is known as Hubble's Law. This data best supports the Redshift/Hubble's Law evidence for the Big Bang. The Big Bang model predicts that the universe has been expanding since it began. If the universe is expanding, galaxies should be moving apart, and the farther a galaxy is, the faster it should be moving away — which is exactly what the redshift data shows. Light from these galaxies is stretched toward the red end of the spectrum because space itself is stretching. When scientists reverse this expansion backward in time, all matter would have been compressed together at a single point, which is consistent with the Big Bang model.

Question 17

[FIGURE: Diagram showing two side-by-side star life cycle pathways. Left pathway labeled 'Lower-Mass Star (like our Sun)': Nebula → Protostar → Main-Sequence Star → Red Giant → White Dwarf. Right pathway labeled 'Massive Star (much greater mass than Sun)': Nebula → Protostar → Main-Sequence Star → Red Supergiant → Supernova → elements scattered into space. Each stage is connected by arrows. The Supernova stage on the right pathway has a callout bubble listing example heavy elements: gold, silver, uranium, iron, oxygen, carbon.]

Using the diagram above and what you know about nuclear fusion and the life cycle of stars, answer the following: (1) Explain why massive stars are able to produce heavier elements than lower-mass stars. (2) Explain why a supernova is a necessary step in getting those heavy elements into planets like Earth. (3) Connect this process to the larger cosmic timeline — how does what happens inside stars eventually lead to Earth forming?

Accepted Answer

Massive stars can produce heavier elements because their greater mass creates higher core temperatures and pressures. This allows nuclear fusion to continue beyond hydrogen and helium, fusing progressively heavier nuclei — carbon, oxygen, and eventually iron. Lower-mass stars like our Sun do not have enough mass to generate the extreme conditions needed to fuse elements heavier than carbon. A supernova is necessary because elements created inside a star are trapped in its core. When a massive star explodes in a supernova, it scatters those heavy elements — like gold, silver, and uranium — out into space. Without the supernova, those elements would never leave the star and could not become part of new solar systems. In the larger cosmic timeline, the Big Bang produced mostly hydrogen and helium. Gravity pulled those gases into the first stars, which used nuclear fusion to create heavier elements. When those stars exploded as supernovae, they spread heavy elements into space. Over time, gravity pulled that enriched gas and dust (a nebula) together again. About 4.6 billion years ago, our solar nebula collapsed — the Sun formed at the center, and the remaining material clumped together to form the planets, including Earth. Earth is literally made of recycled star material.

Unit Test: Origins of the Universe and Earth

Part A: Multiple Choice

Part B: Short Answer

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