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

Grade 9 Science Worksheet - Challenge Me

Circle the best answer.

1. 1.

   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; scientists have stopped studying the question altogether
   • 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
2. 2.

   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?

   • Correct; proteins came first, then DNA, then RNA
   • No; it proposes that stromatolites came first
   • 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

3. Read this first

   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.

4. 3.

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

   • About 4.5 billion years, since life began with Earth
   • About 50 million years
   • About 0.5 billion years (500 million)
   • About 8.5 billion years
5. 4.

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

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

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

   • Living bacteria found in the air of the giant planets
   • Amino acids that formed in a flask of living bacteria in 1953
   • 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

8. 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.

9. 7.

   Which result best supports that life's building blocks can form from simple chemicals, by Ren's reading (NASA)?

   • Stromatolites formed from sea-floor sand with no microbes involved
   • Miller–Urey sparks made amino acids from water and simple gases
   • DNA forms first in a cell, with no proteins needed
   • Living cells came out of the 1953 flask

10. 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.

11. 8.

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

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

12. 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.

13. 9.

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

    • 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
    • Sunlight on rocks made DNA and settled how life began
14. 10.

    RNA, DNA and a protein, with the jobs each can do. Which summary of the RNA world idea fits NASA, by Bo's reading?

    • DNA came first and later turned into RNA and proteins, which then took over its jobs
    • RNA cannot store data, so proteins came first
    • RNA may have stored data and sped reactions before DNA and proteins took over
    • RNA was found fully formed in a 1953 flask