BIOB 160 Principles of Living Systems · Unit 1: The chemistry of life · on Exam 1
1.1 The study of life
Study notes for The study of life in BIOB 160 Principles of Living Systems at Montana State University: the big ideas, a worked example, common mistakes and an exam tip. The same topic has endless practice questions and flashcards in StudyCat.
Big ideas
- Living things share properties: order, evolutionary adaptation, response to the environment, regulation (homeostasis), energy processing, growth and development, and reproduction.
- Biology is organized in levels: molecules → organelles → cells → tissues → organs → organisms → populations → communities → ecosystems → the biosphere. Emergent properties appear at each level from the arrangement and interactions of parts.
- Five unifying themes: organization (structure fits function), information (DNA → RNA → protein), energy and matter (energy flows through ecosystems, matter cycles), interactions (feedback regulation) and, the core theme, evolution.
- Life is classified into three domains: Bacteria and Archaea (prokaryotes) and Eukarya (protists, plants, fungi, animals). Darwin’s natural selection explains both the unity and the diversity of life.
- Science tests hypotheses: explanations that must be testable and falsifiable. A controlled experiment changes one independent variable, measures a dependent variable and compares against a control group. A theory is broad and backed by a large body of evidence.
Worked example
Students test whether fertilizer increases bean plant height. They grow 20 plants with fertilizer and 20 without, same light and water, and measure height after 3 weeks. Name the independent variable, the dependent variable and the control.
Show the solution
Independent variable: fertilizer (present or absent). Dependent variable: plant height. Control group: the 20 plants without fertilizer. Light and water are held constant as controlled variables.
Common mistakes
- Calling a hypothesis “proven”. Evidence supports or fails to support a hypothesis; it can be falsified.
- Confusing the independent variable (what you change) with the dependent variable (what you measure).
- Thinking a scientific theory is a guess. In science a theory is well supported and broad.
Exam tipReading: Campbell ch. 1 (pp. 2–15). Expect an experimental-design question: identify variables, the control and whether the conclusion follows.
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