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Environmental Science

Unit 1

Introduction to Environmental Science

5 topics · 21 practice questions · Free responseNot yet reviewed

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Notes

The science and its systems

  • Environmental science is interdisciplinary: it uses biology, chemistry, geology, and social science to study human-environment interactions.
  • A system has inputs, outputs, and parts that interact. Earth's spheres are the atmosphere, hydrosphere, geosphere, and biosphere.
  • Negative feedback counteracts change (stability). Positive feedback amplifies change (melting ice lowers reflectivity and causes more warming).

Scientific method

  • Form a testable hypothesis, change one independent variable, measure the dependent variable, and keep other variables controlled.
  • Use a control group for comparison, repeat trials, and use peer review.
  • Correlation does not prove causation.

Sustainability and footprint

  • Sustainability meets present needs without harming future generations. Renewable resources replenish quickly; nonrenewable ones do not.
  • Sustainable yield is the harvest that does not reduce the supply. The tragedy of the commons is overuse of shared resources.
  • The ecological footprint measures resource use and waste in area. When it exceeds biocapacity, there is ecological overshoot.
  • $I = P \times A \times T$ (population, affluence, technology).

Topics in this unit

Each topic has its own short notes and practice.

Practice

A scientist changes the amount of road salt added to several identical soil samples and measures plant height. The independent variable is:
Which is an example of a negative feedback loop?
Which pairing of resource and type is correct?
A fishery harvests 12,000 kg per year, but the fish population only adds 9,000 kg per year. What will most likely happen?
A city's footprint is 3 times its local biocapacity. Which statement is correct?
Which of these is the best example of a hypothesis that can be tested?

Free response

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Free-response question

A school wants to know whether adding compost to garden soil helps bean plants grow. A student sets up 3 identical garden beds: bed A gets no compost, bed B gets 1 kg of compost, and bed C gets 3 kg of compost. All beds get the same sunlight and water.

(a) Identify the independent variable, the dependent variable, and the control group.

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Independent variable: the amount of compost. Dependent variable: bean plant growth (such as height or mass). Control group: bed A, which receives no compost.

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(b) Name two variables that must be kept constant and explain why.

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Sunlight and water (also bean variety, bed size, soil type). Keeping them equal ensures that differences in growth are caused by compost and not by another factor.

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(c) The student finds that bed C grew the tallest. Explain why more trials are still needed before a firm conclusion.

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Repeating the experiment with more beds reduces the effect of chance and random differences, and shows whether the result is reliable. Other scientists should be able to repeat it and get similar results.

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