What is Science? Plant Biology 006, Spring 2016

Science is a way of knowing Science is a way of knowing. It is a formal process of asking questions about the world and seeking explanations.

All scientific advances begin with an inquisitive mind carefully observing natural phenomena The scientific method: Make observations and ask questions Develop a hypothesis

What is a hypothesis? A hypothesis is a provisional explanation of some phenomenon. Scientific hypotheses are never proven to be true. Rather, they are subject to testing and if they are not established to be false, they continue to be accepted.

Science proceeds by the testing of hypo- theses, with the goal of falsifying them (shooting them down). A hypothesis that has not been falsified is allowed to stand as the provisional truth.

The scientific method: Make observations and asking questions Develop a hypothesis Use the hypothesis to make predictions Use experiments to test the hypothesis Modify the hypothesis based on experimental results

Question: How do plants grow? Hypothesis: Plants grow by eating soil. Jan Baptista van Helmont ca. 1577-1644 .

Figure 1.19 Idealized version of the scientific method Trees grow larger with passing time. How is this possible? Trees grow larger by absorbing material from the soil. If a tree is grown in a pot of soil, the weight of the soil should decrease as the weight of the tree increases.

What happened? At the end of five years, the willow tree had increased in weight by 74.4 kilograms. The soil had decreased in weight by only 57 grams!

Conclusion: The hypothesis had been falsified: it was demonstrated that plants do not increase in size by absorbing material from the soil.

Q. Which of the following best represents an application of the Scientific Method? A student memorizes the Periodic Table of the Elements A homeowner checks his fuel tank to see if that’s why his furnace won’t come on An anthropologists finds a fossil hominid older than any yet known Geneticists completely sequence the human genome

Lecture Review, Chapter 1 Define science in your own words. What is a hypothesis? Describe how van Helmont’s 5-year tree experiment followed the scientific method. Give a practical example of use of the scientific method in everyday life.