Topics Covered: The scientific method Characteristics of life Tools Used in Biology

Section 1-2 How Scientists Work: The Steps of the Scientific Method  Step 1: Make an Observation An observation is the process of gathering information about events or processes in a careful, orderly way. The information collected by observations is called data.

Section 1-2 How Scientists Work: The Steps of the Scientific Method  Step 2: State the problem or ask a question.

Section 1-2 How Scientists Work: The Steps of the Scientific Method  Step 3: Make a hypothesis. A hypothesis is a possible explanation for a set of observations. For a hypothesis to work: ○ It must be testable ○ It must be falsifiable (there would be a way to tell if it is incorrect)

Section 1-2 How Scientists Work: The Steps of the Scientific Method  Step 4: Develop an Experiment and Record Data Many are controlled experiments: when a hypothesis is tested by changing one variable at a time, all other variables should be kept unchanged or controlled. What is a variable? ○ Something that is likely to change in an experiment.

 In a controlled experiment there are typically 2 variables: The independent variable is the part of the experiment that the scientist chooses to purposely change. The dependent variable is the part of the experiment that changes because of the independent variable (usually the variable that the scientist is measuring.) Section 1-2 How Scientists Work: The Steps of the Scientific Method

 Good experiments… Test more than one subject for or repeat the experiment several times. Scientists must be sure to keep careful notes during an experiment so that other scientists can repeat exactly the same experiment and observe the same results.

Section 1-2 How Scientists Work: The Steps of the Scientific Method  Step 5: Draw a conclusion. Was the original hypothesis statement supported by the experiment or not? If the hypothesis is not supported the scientist may want to change their original hypothesis or their experiment. The scientist should repeat the experiment to see if they observe the same results.

The Steps of the Scientific Method  The development of a scientific theory. A theory is a widely accepted explanatory idea that is broad in scope and supported by lots and lots of experimentation! A theory is only accepted by the scientific community when the theory is supported by many different experiments and observations.  Ex. The cell theory, the big bang theory, the theory of evolution.

The Steps of the Scientific Method  Step 1: Make an Observation.  Step 2: Ask a question.  Step 3: Make a hypothesis.  Step 4: Develop an experiment and record data.  Step 5: Draw a conclusion.

1-3 Studying Life: The 8 characteristics of living things 1.All living things are made of cells. A cell is a bag of living material. Living things can be unicellular (made of one cell) Living things can be multicellular (made of many cells)

1-3 Studying Life: The 8 characteristics of living things 2.All living things reproduce. Types of reproduction: ○ Asexual reproduction - a new organism is made from a single parent ○ Sexual reproduction - cells from two different parents unite to produce a new organism.

1-3 Studying Life: The 8 characteristics of living things 3.All living things are based on a genetic code. DNA is the molecule that helps to transfer genetic information from one generation to the next.

4.All living things grow and develop. To grow means to get larger over time. To develop means to change over time. 1-3 Studying Life: The 8 characteristics of living things

5.All living things have need for materials and energy. Metabolism refers to the chemical reactions that an organism uses to build up or break down materials. Most living things rely on energy stored in the process of photosynthesis. 1-3 Studying Life: The 8 characteristics of living things

6.All living things respond to the environment. Stimuli are signals from the environment to which living things respond. 1-3 Studying Life: The 8 characteristics of living things

7.All living things are able to maintain an internal balance. The process by which living things keep their insides stable is called homeostasis. 1-3 Studying Life: The 8 characteristics of living things

8.All living things evolve. Evolution is when organisms as a group change over time. 1-3 Studying Life: The 8 characteristics of living things

Chapter 1-3: Branches of Biology  Biology can be studied at many levels they are listed here from the smallest, least complex system to the largest, most complex system: Molecules Cells Tissues Organs Organ systems Organism

1-4 Tools and Procedures  Biologists use the metric system of measurement. This measurement system is based on multiples of ten. Meters (length) Grams (mass) Liters (volume)  Microscopes are used to produce magnified images of things that are too small to see with the unaided eye.

 Light Microscope: a tool that magnifies by allowing light to pass through the object being observed Make it possible to study living and dead cells Type of microscope we will use in class 1-4 Tools and Procedures

 Electron microscopes used to study smaller objects, they use beams of electrons to produce images. All specimens must be dead in order to observe them. 1-4 Tools and Procedures

Objectives for this Unit: