Chapter 2: The Scientific Process

Scientific Process

How do scientists solve problems? -scientific method: questioning how things are done
What is the process of peer review? - other scientists in the field need to redo your experiment and decide if your results make sense
- Why is this important? - prevents improper science and bias
What is empirical evidence? - evidence from observation and experimentation

Activity

Questions - why is mom showing favoritism
Hypothesis - brighter colored ones able to beg for food
Prediction - baby birds of the species will become more brightly colored over time
How to test - tagging and weighing
- Dependent - size, lifespan, survival rate
- Independent - brightly colored
- Check their weight every week by taking them out and weighing them, lifespan, rate of feeding
- 10 different nests - want larger numbers
What are scientists always looking for? - evidence
What are the four important features of the scientific process? - curiosity, skepticism, reproducibility, peer review
What is a scientific theory? - rarely overturned unless new evidence discredits it
What is scientific law and the law of nature? - well-tested and widely accepted description of what we find happening repeatability and in the same way in nature
What are the limitations of science? - cannot prove or disprove anything absolutely, not free of bias about hypotheses and results, systems in the natural world involve a huge number of variables and complex interactions
What is an organic compound? - compound containing at least two carbon atoms
- What are the types of organic compounds? - hydrocarbons and carbohydrates
- What is a macromolecule? - complex organic molecules
- What are some examples? - complex carbohydrates, proteins, nucleic acids, lipids
What kinds of changes does matter go through? - physical, chemical, nuclear
- What is a physical change? - no change in chemical composition
- What is a chemical change? - change in chemical composition
- What is a nuclear change? - radioactive decay where neutrons are lost over time, nuclear fusion when particles fuse, nuclear fission where particles break apart and release energy

What forms does energy come in? - kinetic, potential

What is kinetic energy? - energy of movement: heat and electromagnetic radiation
- What is an example? - wind’s kinetic energy moves turbines
What is potential energy? - stored energy: can be changed into kinetic energy
- What is an example? - water stored behind a hydroelectric dam

Hubbard Brook Forest

Would it be smart to cut down trees near a reservoir in order to preserve drinking water? - no, cutting down trees would do more harm than good because they will use rain water more often than water in the reservoirs
- Experiment? - cut down all of the trees around one reservoir, half of the trees on another, and leave a third one’s trees untouched
- Measurement? - You could measure the water volume before and after the cuts, and measure how much was consumed by humans, the resulting difference would be how much water the trees used, precipitation levels, water flow
What is a watershed? - precipitation falls and goes to a central location
What is a stream gaging station? - also called a weir, v-notch at the end of a brook measures water flow through it
What is evapotranspiration? - rate at which plants take water up through the ecosystem and evaporate it into the atmosphere
What patterns do you notice from the graph? - precipitation affects streamflow, evapotranspiration and precipitation have the same general shape, streamflow is relatively the same until 1965
Are there any conclusions we can draw from the data? - watershed 2 which is clear cut had higher streamflow, lower evapotranspiration rates in clear cut forest
What happened in 1965 that caused a split in the streamflow? - clear cut of the forest
Why would precipitation not increase when evapotranspiration does? - scale is too small
What do we call calcium, potassium, and nitrate? - nutrients
Where do nutrients end up when a forest is clear cut? - bodies of water
What happened to the clear-cut site? - 30-40% more runoff, more dissolved nutrients, more soil erosion
- Why would there be more soil erosion in the clear-cut forest? - roots stabilize soil, losing it makes it looser
What are systems and how do they respond to change? - systems have inputs, flows, and outputs of matter and energy, and feedback can affect their behavior
How do systems respond to change? - feedback loops
- What is a system? - set of components that interact in a regular way
- What are some examples of a system? - human body, earth, economy
- What is a feedback loop? - any process that increases or decreases a change in a system
- What are the types of feedback loops? - positive and negative
  - What is a positive feedback loop? - causes system to change further in the same direction
  - What is a negative feedback loop? - also known as corrective feedback, causes system to change in opposite direction
  - What type of feedback loop is the Hubbard Brook experiment? - positive
Albedo - object’s ability to reflect light
Describe a feedback loop - a process in which the result either continues or does the opposite of what it originally did
How does time play a role in feedback loop responses? - systems change over time
What is energy and how does it undergo change? - energy is the ability to do work, it can change when it is used and changes from high to low quality
What is a time delay in a feedback loop? - amount of time between the input of feedback stimulus and its response
What is a tipping point/threshold level? - fundamental shift in system behavior
What are the first two laws of thermodynamics? - energy is neither created nor destroyed, we end up with less usable energy than we started with
What is renewable energy? - gained from resources that are replenished by natural processes in a relatively short time
What is nonrenewable energy? - resources can be depleted and are not replenished by natural processes within human timescales
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