Chapter 1 The Science of Biology

1–1 What Is Science? Science is a process of inquiry, asking questions, the answers to which produce a body of knowledge, which is subject to change and revision. The goal of science is to investigate and understand the natural world, to explain events in the natural world and to use those explanations to make useful predictions.

Science only deals with the natural world Science only deals with the natural world. Biology is a field in science that focuses on the study of life. An understanding of science and the scientific approach is essential to making intelligent decisions.

Scientists collect and organize information in a careful, orderly way, looking for patterns and connections between events. Scientists propose explanations that can be tested by examining evidence. Scientists try to explain events logically and analytically.

Scientific thinking begins with observation, the process of gathering information about events or processes in a careful, orderly way. Observation generally involves using the senses, particularly sight and hearing. The information gathered from observations is called data. Data consists of observations that do not differ whether collected by one person or another. Eg. Flame from a lighter/Candle Flame

Two types of data: Quantitative data: expressed in numbers, obtained by counting or measuring. Qualitative data: descriptive and involves characteristics that can’t usually be counted.

Scientists use data to make inferences, a logical interpretation based on prior knowledge or experience. After initial observations, a hypothesis is proposed. A hypothesis is a proposed scientific explanation for a set of observations. Scientific hypotheses must be proposed in a way that enables them to be tested.

Science is an ongoing process, knowledge is constantly being reevaluated, revised and updated because of new tools, techniques and discoveries. Good scientists are skeptics, questioning existing ideas and new hypotheses. Common steps for scientists to gather information and answer questions are known as scientific methods. Not every scientific investigation uses every method nor do all investigations lead to scientific theory.

1-2 How Scientists Work While there are no fixed steps, generally the scientific method involves: MAKE OBSERVATIONS: observations utilize the senses to gather information. Scientific discovery often takes place when a scientist observes something no one has noticed before.

ASK A QUESTION: observations may lead to unanswered questions ASK A QUESTION: observations may lead to unanswered questions. (Research may provide information about previous investigations of the question or suggest appropriate approaches to the problem.) FORM A HYPOTHESIS: an explanation for a question or a problem that can be formally tested. A good hypothesis predicts a relationship between cause and effect.

SET UP A CONTROLLED EXPERIMENT: While we use the term experiment informally, a scientific experiment is an investigation that tests a hypothesis by the process of collecting information under controlled conditions. A controlled experiment involves two groups:

Variable (Experimental) group: test group that receives experimental treatment. A variable is the factor of an experiment that can change. In a controlled experiment, only one variable is tested at a time. There are three types of variables: Controlled (constant) variables: same for both the control and variable group. Manipulated (independent) variable: variable that is deliberately changed. Responding (dependent) variable: changes in response to the manipulated variable (what happened).

Control group: group that receives no experimental treatment, the standard against which results are compared.

RECORD AND ANALYZE RESULTS: keeping a written record of observations and data. Data from an investigation can be considered confirmed only if repeating the investigation several times yields similar results. DRAWING A CONCLUSION: Use evidence to determine whether the hypothesis was supported or refuted.

REPORTING RESULTS: Results are only useful if they are made available to other scientists for peer review. Other scientists can try to verify the results by repeating the procedure.

It is not always possible to do an experiment to test a hypothesis. Alternative investigations may utilize fieldwork or surveys or large groups of subjects, controlling as many variables as possible. As evidence accumulates from scientific investigations, a particular hypothesis may become so well supported that scientists consider it a theory. A theory is a well-tested explanation that unifies a broad range of observations. No theory is considered absolute truth. As new evidence is uncovered, a theory may be revised or replaced.

1 – 3  Studying Life The word biology means the study of life. A biologist is someone who uses scientific methods to study living things. Describing what makes something alive is not easy. No single characteristic is enough to describe a living thing. Some non-living things share one or more traits with living things.

Section 1-3 THE CHARACTERISTICS OF LIVING ORGANISMS

There are 7 characteristics: Movement Respiration Sensitivity Growth Reproduction Excretion Nutrition

Movement An action by an organism or part of an organism causing a change of position or place.

Respiration The chemical reactions that break down nutrient molecules in living cells to release energy

Sensitivity The ability to detect or sense changes in the environment (stimuli) and to make responses.

Growth A permanent increase in size and dry mass by an increase in cell number or cell size or both.

Reproduction The processes that make more of the same kind of organism

Excretion The removal from organisms of toxic materials, the waste products of metabolism (chemical reactions in cells including respiration) and substances in excess of requirements.

Nutrition The taking in of nutrients which are organic substances and mineral ions, containing raw materials or energy for growth and tissue repair, absorbing and assimilating them.

Summary: Write down the terms Movement Respiration Sensitivity Growth Reproduction Excretion Nutrition

Quiz Guess which characteristic is being demonstrated by the following animations:

Question 1

Question 2

Question 3

Question 4

Question 5 Which two characteristics are shown by this animation:

Question 6 Other than movement, which characteristics are shown by this animation:

Question 7 So far you should have named a total of five different characteristics. However there are 7 characteristics in total. Name the two remaining characteristics.

Answers: How well did you do?

Question 1: Excretion

Question 2: Nutrition

Question 3: Movement

Question 4: Reproduction

Question 5: Sensitivity and Movement Which two characteristics are shown by this animation:

Question 6: Sensitivity and Nutrition Other than movement, which characteristics are shown by this animation:

Question 7: Growth and Respiration So far you should have named a total of five different characteristics. However there are 7 characteristics in total. Name the two remaining characteristics.

Now you should be able to Define the characteristics of living organisms

Copyright Pearson Prentice Hall 1-4 Tools and Procedures Photo Credit: © Andrew Syred/Science Photo Library/Photo Researchers, Inc. Copyright Pearson Prentice Hall

A Common Measurement System What measurement system do most scientists use? Copyright Pearson Prentice Hall

A Common Measurement System Most scientists use the metric system when collecting data and performing experiments. Copyright Pearson Prentice Hall

A Common Measurement System Because the metric system is based on multiples of 10, it is easy to use. Copyright Pearson Prentice Hall

A Common Measurement System 1 meter (m) = 100 centimeters (cm) 1 meter = 1000 millimeters (mm) 1000 meters = 1 kilometer (km) 1 kilogram (kg) = 1000 grams (g) 1 gram = 1000 milligrams (mg) 1000 kilograms = 1 metric ton (t) 1 liter (L) = 1000 milliliters (mL) 1 liter = 1000 cubic centimeters (cm3) 00C = freezing point of water 1000C = boiling point of water Scientists usually use the metric system in their work. This system is easy to use because it is based on multiples of 10.

Copyright Pearson Prentice Hall Microscopes How are light microscopes and electron microscopes similar? How are they different? Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Microscopes Microscopes Microscopes are devices that produce magnified images of structures that are too small to see with the unaided eye. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Microscopes Light Microscopes The most commonly used microscope is the light microscope. Light microscopes produce clear images of objects at a magnification of about 1000 times. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Microscopes Compound light microscopes allow light to pass through the specimen and use two lenses to form an image. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Microscopes Electron Microscopes To study even smaller objects, scientists use electron microscopes. Copyright Pearson Prentice Hall

Laboratory Techniques Cell Cultures A single cell is able to reproduce so that a group of cells, called a cell culture, develops from the single original cell. Copyright Pearson Prentice Hall

Laboratory Techniques Cell Fractionation Biologists often use a technique known as cell fractionation to separate the different cell parts. Copyright Pearson Prentice Hall

Working Safely in Biology Follow safe practices. Study the safety rules. Read all the steps and safety precautions. Follow your teacher’s instructions and textbook directions exactly. If in doubt, ask your teacher for an explanation. Wash your hands thoroughly with soap and warm water after every scientific activity. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 1-4 A single measurement system is commonly used in science because it allows scientists to easily replicate one another’s experiments. basic units of mass, length, and volume are unrelated to one another. more kinds of measurements can be made. computers can store large amounts of scientific data. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 1-4 Compared to a light microscope, an electron microscope is used to observe larger objects with less detail. larger objects with more detail. smaller objects with more detail. smaller objects with less detail. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 1-4 A device that separates cell parts is a centrifuge. cell culture. light microscope. electron microscope. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 1-4 A technique in which cells are grown in a nutrient solution is known as staining. cell fractionation. cell culturing. cell fertilizing. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 1-4 When you work in a biology laboratory situation, your first priority should be to make sure all materials are available. modify any instructions that do not make sense. familiarize yourself with all safety rules before beginning to work. know ahead of time what kinds of results to expect. Copyright Pearson Prentice Hall

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