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Module 13 Lesson 1 Progress Check

For the geological timescale content on p.350-355, you only need to know how time is measured in the geologic timescale, Precambrian, Cambrian explosion, K-T boundary, plate tectonic movement.

Complete questions Lesson 1: #1, 3, 4, 5, 6

Response

  1. Discuss how fossils provide evidence of change from the earliest life-forms to those alive today.

    Fossils provide evidence of the evolution of life from simple to complex organisms over billions of years by showing gradual changes in physical structures and species diversity. They capture snapshots of past life, including extinct species, which help scientists understand the development of life forms that are alive today.

  2. Discuss two ways that radiometric dating can be used to establish the age of a fossil.

    Radiometric dating measures the decay of radioactive isotopes in rocks and fossils to determine their age; for example, carbon-14 dating is used for organic remains up to about 50,000 years old, while uranium-lead dating can date rocks from millions to over a billion years old, providing a time frame for fossil formation.

  3. Compare Earth's early land environment with today's land environment.

    Earth's early land environment was initially inhospitable, with volcanic activity and a lack of oxygen, contrasting sharply with today's diverse ecosystems that include forests, deserts, and grasslands. Over time, the atmosphere became oxygen-rich due to photosynthesis by early life forms, allowing for the development of complex land ecosystems.

  4. Infer what changes you might observe in the fossil record that would indicate the occurrence of a mass extinction.

    In the fossil record, mass extinctions are indicated by a sudden, widespread decrease in the diversity and abundance of many different species across various groups, often followed by a period where new species gradually emerge to fill the vacant ecological niches. This pattern reflects significant and rapid environmental changes that abruptly disrupt life on Earth.

  5. Math Connection: Out of the total Earth's history (approximately 4.6 billion years ago), modern humans have existed for only 200,000 years. To put this in perspective, calculate the percentage of Earth's history that modern humans have existed.

    \[\frac{200,000}{4,600,000,000} \times 100 = 0.00435\%\]