Chapter 1. Chapter 2 Study Guide

Guiding Question 2.1

Why You Should Care

You can be certain that scientists are never certain—because the scientific method never proves anything with 100% certainty. This can cause confusion with non-scientists who want definite answers. Adding to the confusion is the fact that scientists use the term ‘theory’ completely differently than the general public. Understanding the process of science and its limitations will help you better understand and interpret scientific evidence.

What kinds of enquiry, process, and knowledge are considered ‘science’? Position the brackets along the ‘knowledge spectrum’ to indicate where science fits in.

Figure : [Interactive Infographic 2.2 TK]

Guiding Question 2.2

Why You Should Care

Understanding how scientists form and test hypotheses will help you understand scientific information in your daily life. Whenever you watch the news and hear that Food X causes cancer, you shouldn’t accept that as fact. Instead you should consider the science behind the news story. A group of scientists must have suspected that Food X might cause cancer and tested this hypothesis. But what kind of study did they eventually use? What if the findings by the scientists were from a completely observational study, such as a survey to determine how many cancer patients consumed large amounts of Food X? If this were the case, then only a connection between cancer and Food X can be made. It would take an experiment for the researchers to claim that Food X causes cancer.

Figure 1.1: Infographic 2.3

Figure 1.2: Infographic 2.5

Read the description of each study below and decide whether it is experimental or observational.

Guiding Question 2.3

Why You Should Care

Because Ultraviolet radiation has more energy than visible light, it can cause chemical changes in some molecules; sun fading, for example happens because UV can break down pigment molecules. UV can also affect biological molecules like proteins and DNA. Suntans, in fact, are the body’s response to excessive genetic damage from UV exposure. Sunscreens work by absorbing UV before it can cause damage to skin cells.

Just like sunscreen, ozone in the stratosphere can absorb the energy from UV and dissipate it before it reaches the earth. The depletion of ozone from its interaction with human-made CFCs is cause for concern because it is allowing more UV to pass through. Since the genetic damage UV causes may lead to cancer, there is concern that rates of skin cancer will increase globally.

Figure : Infographic 2.1 The Atmosphere and UV Radiation

The scientists who named the layers of the atmosphere did not simply pick arbitrary altitude ranges. Each layer is different from the others in terms of many different characteristics. Based on this Infographic and the information in the chapter, can you determine what some of those characteristics are?

[PLACEHOLDER FOR ATMOSPHERIC TABLE]

Figure 1.3: Infographic 2.4 The Chemistry of Ozone Formation and Breakdown

Guiding Question 2.4

Why You Should Care

By now you’ve probably noticed that the overarching theme of this chapter is what science does and doesn’t do. While it’s important to know that science never answers a question with 100% certainty and for every question answered a new one is asked, that doesn’t mean that scientific findings can’t be used to improve our lives.

Figure : Infographic 2.7

Guiding Question 2.5

Why You Should Care

As with experts in any field, scientists often have a difficult time getting non-experts to understand the value and implications of their findings. The Montréal Protocol is one of the best examples of scientists succeeding at using evidence to lead to policy changes that are helping a negative situation.

Figure : Infographic 2.6

Short Answer Review Questions

Similar to the findings that CFCs released by human activity into the atmosphere coincided with depletion of the ozone layer, atmospheric scientists have also discovered a relationship between the human release of so-called ‘greenhouse gases’, like carbon dioxide and methane, and an average increase in global temperature. Like the Montréal Protocol, the Kyoto Protocol was an international compact to reduce emissions of these gases, but unlike the Montréal Protocol, it was never ratified by enough countries to make it a viable agreement.