**Optional.** Scientific ideas about how life began

Grade 9 Science Worksheet - Challenge Me

Circle the best answer.

1. Read this first

   Table, The Miller–Urey experiment (NASA), with columns Part, What it stood for or gave

   Flask of water, an early ocean; Methane, ammonia, hydrogen and water vapor, an early atmosphere, as Urey proposed; Electric sparks, lightning; Result in 1953, 5 amino acids identified; Re-analysis in 2008 of a sibling experiment, 22 amino acids.

2. 1.

   A classmate says the Miller–Urey experiment created life in a flask. Which reply fits NASA, by Esme's reading?

   • No; the flask stayed exactly as it started, with no new molecules
   • No; it made amino acids, building blocks of proteins, not living cells
   • Correct; bacteria grew in the flask within a few days after the sparks were sent
   • Correct; it made complete cells that held both DNA and RNA
3. 2.

   A pond, a tide pool, a hot spring and a seafloor vent chimney. A student says scientists know exactly how life began. Which reply fits NASA, by Jun's reading?

   • No; it is an open question, studied with lab chemistry and ancient fossils
   • Correct; the 1953 experiment answered the whole question for good
   • Correct; vent tests in a lab made the first living cell from rock
   • No; scientists have stopped studying the question altogether
4. 3.

   RNA, DNA and a protein, with the jobs each can do. A student says the RNA world idea means DNA came first. Which reply fits NASA, by Kira's reading?

   • No; it proposes RNA first, later replaced by DNA and proteins
   • Correct; DNA came first, and then RNA was copied out from it later on
   • No; it proposes that stromatolites came first
   • Correct; proteins came first, then DNA, then RNA

5. Table, Early Earth timeline (NASA), with columns Event, When

   Earth forms, about 4.5 billion years ago; Possible earliest signs of life, about 4 billion years ago; Pilbara stromatolites, Australia, about 3.5 billion years ago; Miller–Urey paper in Science, May 15, 1953.

6. 4.

   Using the timeline, how much older is Earth than the possible earliest signs of life, by Luz's math?

   • About 50 million years
   • About 0.5 billion years (500 million)
   • About 4.5 billion years, since life began with Earth
   • About 8.5 billion years
7. 5.

   Model scale: Earth's 4.5-billion-year history is one 24-hour day starting at midnight. About when would the 3.5-billion-year-old stromatolites appear, by Milo's math?

   • About 3:30 a.m.
   • About 6:40 p.m.
   • About 1:00 a.m.
   • About 5:20 a.m.
8. 6.

   Model data: a stromatolite grew 0.4 mm a year for 2,500 years. How tall did it grow, by Noah's math?

   • About 2,500.4 mm
   • About 100 mm
   • About 6,250 mm
   • About 1,000 mm (1 m)
9. 7.

   Which evidence best supports that life existed 3.5 billion years ago, by Pia's reading (NASA)?

   • RNA strings that grew into full genes at a lab bench in 2016, on their own
   • Pilbara stromatolites, built by microbial mats about 3.5 billion years ago
   • Living bacteria found in the air of the giant planets
   • Amino acids that formed in a flask of living bacteria in 1953
10. 8.

    A pond, a tide pool, a hot spring and a seafloor vent chimney. Two hypotheses: life began in a warm pond, or at a deep-sea vent. Which kind of evidence could help test them, by Tala's reading?

    • A vote on which idea sounds nicer to most people
    • Lab tests of which setting forms and protects molecules like RNA
    • Assuming that the older idea must be the right one
    • Counting how many stars can be seen in the sky

11. Table, Early Earth timeline (NASA), with columns Event, When

    Earth forms, about 4.5 billion years ago; Possible earliest signs of life, about 4 billion years ago; Pilbara stromatolites, Australia, about 3.5 billion years ago; Miller–Urey paper in Science, May 15, 1953.

12. 9.

    Which summary of the early-life timeline fits NASA, by Zee's reading?

    • Earth is about 3.5 billion years old; life began 4.5 billion years ago
    • Earth: about 4.5 billion years; life: maybe 4 billion; stromatolites: 3.5 billion
    • Life began about 3.5 billion years before Earth itself formed
    • Earth is about 4.5 million years old, and its stromatolites are about 3.5 million

13. Table, The Miller–Urey experiment (NASA), with columns Part, What it stood for or gave

    Flask of water, an early ocean; Methane, ammonia, hydrogen and water vapor, an early atmosphere, as Urey proposed; Electric sparks, lightning; Result in 1953, 5 amino acids identified; Re-analysis in 2008 of a sibling experiment, 22 amino acids.

14. 10.

    Which summary of the Miller–Urey experiment fits NASA, by Ari's reading?

    • Sunlight on rocks made DNA and settled how life began
    • Sparks in oxygen-rich air made living bacteria in about a week, settling the question
    • Sparks in water turned simple gases into stromatolites
    • Sparks in water and simple gases made amino acids, though early air may have differed