Lecture 2 Notes: Scientific Process & History of Life on Earth

Flashcards covering key concepts from Lecture 2 on the scientific process, hypothesis generation, data analysis, and the geological and biological history of Earth including eons, dating methods, and environmental factors.

What is science defined as?

A systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe.

What types of questions can science answer?

Science can answer scientific questions but cannot answer every question.

What is a fact?

Something proven to be true and not disputed.

What is a theory?

A statement of laws/principles/known causes of something observable.

What is a hypothesis?

A proposed explanation based on observation that is to be investigated, i.e., a starting point.

What is the first step in the scientific process?

Observation, which leads to asking questions.

How is a prediction developed in the scientific process?

Using an 'if…then…' statement.

What type of graph is used for comparison of data between datasets, with the y-axis representing the dependent variable and the x-axis representing the independent variable?

Bar charts

What type of graph is used to analyze relationships between two variables, with the y-axis representing the dependent variable and the x-axis representing the independent variable?

Scatter plots

How long ago did Earth form, and when did modern Homo sapiens evolve?

Earth formed 4.6 billion years ago, and modern Homo sapiens evolved only ~160,000 years ago.

What do stratigraphic layers (strata) reveal?

Relative ages, indicating that one layer is older than another.

What do radioisotopes reveal?

Actual ages, for example, that one layer was formed 510 million years ago.

Describe the process of radioactive dating.

During radioactive decay, the nucleus of a parent isotope changes, converting the parent to the daughter isotope at a predictable rate, allowing the calculation of time elapsed since a fossil/rock was formed.

How is Carbon-14 (C14) used in dating?

C14 is gained during life and decays into C12. Acquisition stops at death, but existing C14 continues to convert to C12, allowing calculation of time elapsed since death.

What are the four eons in Earth's biological history?

Hadean, Archean, Proterozoic, and Phanerozoic.

What defines the Hadean Eon (4500-4000 mya)?

It was before life evolved, so there was no life on Earth.

What defines the Archean Eon (4000-2500 mya)?

It begins with the evolution of early life and ends with the emergence of photosynthetic organisms.

What defines the Proterozoic Eon (2500-540 mya)?

It saw the diversification of prokaryotes and the emergence of the first eukaryote.

What defines the Phanerozoic Eon (550 mya-present)?

It encompasses the diversification of multicellular organisms.

How does the physical environment affect biological diversity?

Changes in land masses, climate, sea levels, and atmospheric composition all affect biological life and its diversity.

Can biological life influence the physical environment?

Yes, biological life can actively influence the physical environment.

How do tectonic plate movements influence the biological environment?

Tectonic plate movement shapes the structure of the Earth, thereby influencing the biological environment.

What is Pangea Ultima?

A supercontinent that landmasses are expected to form in approximately 250 million years as tectonic plates continue to move and converge.

Describe the historical pattern of global temperature.

Global temperature is not stable and fluctuates over time, having been both extremely cold (ice age) and extremely hot.