Chapter 1: Biology and You

Section 1-1: The Nature of Science

Key Ideas: How can someone practice scientific thoughts? What are universal laws in science? How do ethics apply to science? Why should someone who is not planning to become a scientist study science?

The goal of science is to help us understand the natural world and improve people’s lives. Thinking like a scientist can help you solve problems and think critically about your world.

What Is Scientific Thought? Scientific Thought- involves making observations, using evidence to draw conclusions, being skeptical about ideas, and being open to change when new discoveries are made.

Scientists observe the world around them and then ask questions about what they observe. This process of making observations and asking questions is the basis of scientific thought. Scientific thought also requires skepticism- a habit of mind in which a person questions the validity of accepted ideas. Scientists require evidence, not opinions, to support ideas.

Ex: People once thought stress caused stomach ulcers Ex: People once thought stress caused stomach ulcers. However, a group of researchers found that bacteria Helicobacter pylori in the stomachs of people with ulcers. Studies confirmed that the bacteria caused ulcers.

Scientific discoveries can change the way people view the world Scientific discoveries can change the way people view the world. Many scientific discoveries lead to new technologies and medical treatments. For example, discovering that bacteria cause stomach ulcers led to prescribing antibiotics for patients with ulcers.

In summary, scientific thought involves: Making observations Being skeptical about ideas Using evidence to draw conclusions Being open to change when new discoveries are made

What are Universal laws? Universal Laws- Science is governed by truths that are valid everywhere in the universe. These truths are called universal laws. Though branches of science address different aspects of the natural world, universal laws apply to all branches of science and every person.

Ex: All objects in the universe are affected by gravity Ex: All objects in the universe are affected by gravity. Whether scientists are studying birds, stars, or landscapes, they must all understand the law of gravity. Birds must overcome gravity to fly. Stars are formed when gravity pulls a mass of gases together.

Why Are Ethics Important In Science? Ethics are a system of moral principles and values. Scientific experimentation and discovery can have serious ethical implications, scientific investigations require ethical behavior.

Ethics cont’d Scientists performing investigations must report only accurate data, be willing to allow their peers to review their work, and behave ethically with the people involved in the investigations. If the data or claims by a scientist are false or misleading the people relying on this discovery/information could be in real danger.

Ex: A scientist falsely claims he found a cure for diabetes; those individuals with diabetes change how they manage their condition to take advantage of the new discovery. Since the information is false those individuals with diabetes can suffer serious consequences.

Why is it important that scientific investigations be done ethically?

Why Study Science? Scientific thinking is not just for scientists. An understanding of science can help you take better care of your health, be a wiser consumer, and become a better-informed citizen.

Why Study Science? You can do this by asking questions about certain claims, be skeptical about what you read, and be ready for discovery and change. You can use science to investigate a problem in your community and discover helpful solutions. You can also use science to improve the world around you.

Key Ideas: How can someone practice scientific thoughts? Scientific thought involves making observations, using evidence to draw conclusions, being skeptical about ideas, and being open to change when new discoveries are made. What are universal laws in science? Science is governed by truths that are valid everywhere in the universe. These truths are called universal laws.

Key Ideas: How do ethics apply to science? Since scientific experimentation and discovery can have serious ethical implications, scientific investigations require ethical behavior. Why should someone who is not planning to become a scientist study science? An understanding of science can help you take better care of your health, be a wiser consumer, and become a better informed citizen.

Section 1-2: Scientific method

Key Ideas: How do scientists know how to begin an investigation? What are two types of experiments that scientists can use to test hypotheses? What is the difference between a theory and a hypothesis?

How Do Scientific Investigations Begin?

Step 1: Making Observations Most scientific investigations begin with observations that lead to questions. Observation is the act of studying objects or events using your senses (sight, hearing, touch, taste, and smell).

Making Observations cont’d Scientists use both direct and indirect observations to study the world around them. Tools, such as microscopes, can also help you make observations. Many observations lead to questions.

Ex: Direct observation: The TV in my room can be seen Indirect observation: The force of gravity cannot be seen; scientists observe gravity indirectly by observing the effects of gravity on objects that can directly be observed.

Step 2: Formulating a Hypothesis Scientists formulate hypotheses to answer these questions. A hypothesis is a possible explanation that can be tested by observation or experimentation. Hypotheses are NOT guesses!

Hypothesis Visual Concept

Step 3: Scientific Experiment In science, an experiment is a set of planned steps, or a procedure that is carried out under controlled conditions to test a hypothesis. Different hypotheses require different kinds of testing. Therefore, not all experiments have the same format.

Scientific Experiment cont’d Experiments can be either quantitative or qualitative. The results of a quantitative experiment can be measured in numbers. The results of a qualitative experiment are generally described in words.

Scientific Experiment cont’d Scientists generally use quantitative experiments in situations in which they can control all the factors that affect the experiment. For example, a scientist may carry out a quantitative experiment to learn how temperature affects a chemical reaction.

Scientific Experiment cont’d Scientists generally use qualitative experiments in situations in which they cannot control all the factors that affect the experiment. Using radio collars to track animals in a natural habitat is an example of a qualitative experiment.

quantitative experiment qualitative experiment Example of the results of a quantitative experiment qualitative experiment The plant given fertilizer grew 10 cm. The plant given no fertilizer grew 2 cm. The trees near the road look less healthy than the trees farther from the road.

CONTROL AND EXPERIMENTAL GROUPS Many scientific experiments use control groups and experimental groups that test one factor at a time, this is called a controlled experiment. A control group is a group in an experiment that receives no experimental treatment. Scientists try to make everything about the control and experimental groups the same except for one factor, or variable.

This variable, which scientists change during the experiment, is called the independent variable. Variables that change as a result of changes in the independent variable are called dependent variables. In many experiments, scientists try to learn how changes in the independent variable affect the dependent variables.

Variables Visual Concept

There are often cases in which experiments are not possible or not ethical. In these cases, researchers perform studies. In a study, researchers gather data about a system by making observations rather than manipulating independent variables.

After conducting an experiment researchers analyze their results to learn whether their results support their hypothesis or not. Scientists draw conclusions that explain the results of their experiments. Scientists verify their conclusions by conducting their experiments.

Every person has his or her own point of view. A particular point of view is called a bias. Scientists try to prevent bias from affecting their work, but bias can still influence an experiment.

Sources of funding, personal involvement in a product, and other conflicts of interest can affect an experiment. It is wise to view all scientific claims in their context and think critically about them.

What Is a Scientific Theory? In everyday speech, people often use the word theory to mean “a guess.” However, in science, a theory is much more than just a guess. A scientific theory is a generally accepted explanation for a large amount of data and observations.

The quantum theory, the cell theory, and the theory of evolution are examples of scientific theories. The figure below shows how observations, questions, hypotheses, and experiments, can lead to the formation of a scientific theory.

Scientific Method Visual Concept

Key Ideas: How do scientists know how to begin an investigation? Most scientific investigations begin with observations that lead to questions. What are two types of experiments that scientists can use to test hypotheses? Scientists conduct controlled experiments or perform studies in order to test a hypothesis.

Key Ideas: What is the difference between a theory and a hypothesis? The main difference between a theory and a hypothesis is that a hypothesis is a specific, testable prediction for a limited set of conditions and a theory is a general explanation for a broad range of data.

Section 1-3: Tools and Techniques

Key Ideas: Why do scientists use the SI system of measurement? What are some tools and techniques that scientists use in the laboratory? What can you do to stay safe during an investigation?

What Is SI? Scientists from all around the world share data. However, different units of measurement are commonly used in different countries. Therefore, scientists use a common measurement system called the International System of Units (SI).

By using SI units, scientists can easily understand and test the results of other scientists. Scientists also use SI because each SI unit can be organized into smaller or larger units based on powers of 10. This makes it easy for scientists to convert between large and small measurements.

Most SI units have a prefix that indicates the relationship between the unit and a base unit. For example, the base unit for length is the meter. The prefix kilo- means 1,000. Therefore, a kilometer is equal to 1,000 meters. The tables on the next pages show common SI base units and prefixes.

Common SI Units Pick up art from page 14, Figure 6 - Common SI Units

Some SI Prefixes

Metric Units of Lengths and Equivalents

What Tools and Techniques Do Scientists Use? When conducting investigations, scientists always make precise measurements and keep detailed notes. Many scientists also use special tools to boost their senses. For example, scientists use microscopes to observe objects that are too small to see with the unaided eye, such as, bacteria.

Two common kinds of microscopes are light microscopes and electron microscopes. In a light microscope, light passes through one or more lenses to produce an enlarged image of an object.

An electron microscope forms an image of an object by using a beam of electrons to magnify extremely small objects. Click

Scientists also use special procedures in the lab. For example, they may use a technique called sterile technique to prevent samples from being contaminated. In addition, scientists can also collect data remotely, using remote tracking devices on released animals.

How Can You Stay Safe in the Lab? Studying science can be exciting, but it can also be dangerous. Here are some guidelines for working safely in the lab: Follow the instructions your teacher gives you. Read your lab procedure carefully before beginning.

Do not skip any steps in your lab procedure. Always wear safety equipment in the lab. Measure chemicals carefully and precisely. Ask your teacher how to get rid of any extra chemicals or materials at the end of a procedure.

Never taste or smell any materials or chemicals in lab unless your teacher instructs you to do so. Do not use any damaged or broken equipment. Keep your lab area clean and organized.

Be careful when you place something on the lab bench. Make sure that the object will not fall or tip over. Walk carefully in the lab.

If you are working outside, be aware of your surroundings. Avoid poisonous plants and dangerous animals that live in the area. Wear sunscreen and a hat that shades your neck and ears.

Before a lab begins, be sure you know where the safety equipment is located and how to use it. If an accident occurs in the lab, stay calm. Make sure that you are safe and that no one else is in danger. Then, inform your teacher right away. Follow all the instructions your teacher gives you.

Key Ideas: Why do scientists use the SI system of measurement? The international System of Units is used by all scientists because scientists need to share a common measurement system. SI is also preferred by scientists because it is scaled by multiples of 10, which makes the system easy to use.

What are some tools and techniques that scientists use in the laboratory? In the lab, scientists always keep detailed and accurate notes and perform precise measurements. Many scientists also used specialized tools, such as, microscopes, and specialized procedures, such as, sterile technique.

What can you do to stay safe during an investigation? Scientists must use caution when working in the lab or doing field research to avoid dangers such as, chemical burns, exposure to radiation, exposure to infectious disease, animal bites, or poisonous plants.

Section 1-4: What Is Biology?

Key Ideas: What are some of the branches of biology? What do biologists study? What are eight characteristics that all living things share?

What Is Biology? Biology is the study of life. Life is extremely diverse. There are many branches of biology, such as, biochemistry, ecology, cell biology, genetics, evolutionary theory, microbiology, botany, zoology, and physiology.

Biologists study the characteristics of organisms, or living things Biologists study the characteristics of organisms, or living things. They also study how organisms interact with their environment. Living things share eight characteristics, shown below, that separate them from nonliving things.

Characteristic Description Cellular Organization A cell is the smallest unit capable of all life functions. A cell is a highly organized structure that is surrounded by a thin covering called a membrane. The basic structure of cells is the same in all organisms. Homeostasis All living organisms must maintain a stable internal environment in order to function properly. The maintenance of stable internal conditions in spite of changes in the external environment is called homeostasis. Metabolism Organisms carry out many chemical reactions to obtain energy. Organisms use energy to grow, to move, and to process information. Metabolism is the sum of all the chemical reactions carried out in an organism. Almost all of the energy used by living things originally comes from the sun. Plants, algae, and some bacteria capture this energy and use it to make molecules.

Responsiveness In addition to maintaining a stable internal environment, living organisms also respond to their external environment. Plants bend toward sunlight. Birds fluff their feathers to insulate their bodies during cold weather. Reproduction Most organisms can reproduce. Reproduction is the process by which organisms make more of their own kind. Heredity/Genetics When an organism reproduces, it passes on its own characteristics, or traits, to its offspring. This is called heredity.

Evolution A species is a group of organisms that can mate to produce offspring. Their offspring can also reproduce. Individuals with traits that help them survive tend to reproduce in larger numbers. They pass along the helpful traits to their offspring. As a result, these helpful traits become more common in the species. Evolution is the change in the inherited traits of a species over many generations (time). Growth All living organisms grow. As organisms grow, many change. This process is called development. Development differs from evolution because development refers to change in a single individual during that individual’s life.

Both the man and the Sequoia tree that he is standing on are living organisms.

Key Ideas: What are some of the branches of biology? Biology includes biochemistry, ecology, cell biology, genetics, evolutionary theory, microbiology, botany, zoology, and physiology. What do biologists study? Biologists study the characteristics of organisms, or living things.

What are eight characteristics that all living things share? The eight properties of life are: cellular organization, homeostasis, metabolism, responsiveness, reproduction, heredity, evolution, and growth.