Section 1-1

Understanding Chihuahuan Desert Fossils

In the Trans-Pecos area of Texas, many fossilized shark teeth have been found. This area of Texas is covered by the Chihuahuan Desert. The fossils are believed to be 100 million years old. The Gulf of Mexico is more than 450 miles away. How could fossils of sharks have formed in the Chihuahuan Desert?

Section 1-1

1.Working with a partner, think of several questions that a scientist might ask in order to understand why there are shark fossils in the desert of Texas. Write these questions on a sheet of paper.

2.Discuss your questions with your partner, and suggest a possible answer to each question.

3.How could a scientist go about finding an answer to each of the questions?

1–1 What Is Science?

A. Goal of Science

B. Thinking Like a Scientist

C. Observation vs. Inference

Section 1-1

Section Outline

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 – organized way of using evidence to learn about the natural world

Section 1-1

Scientific thinking

observation-the process of gathering information about events in a careful, orderly way

data-information gathered from observation

quantitative-expressed as numbers obtained by counting or measured

qualitative-descriptive characteristics that cannot usually be counted

inference-logical interpretation based on prior knowledge or experience

Section 1-1

hypothesis-proposed scientific explanation for a set of observations

Section 1-1

Statement Observation Inference

Object A is round and orange.

Object A is a basketball.

Object C is round and black and white.

Object C is larger than Object B.

Object B is smooth.

Object B is a table-tennis ball.

Each object is used in a different sport.

X

X

X

X

X

X

X

X

Section 1-1

Observation and Inference

Proud to be a COYOTE!

Mystery Worms

Section 1-2

A teacher collected some beetles from a rotting log and placed them in a container of dry oatmeal in her classroom. She kept the box covered with a light cloth so that the beetles could not escape. She also asked one of her students to add potato and apple pieces once a week to provide food and moisture for the beetles. After several weeks, the student reported that there were some strange-looking, wormlike organisms in the container.

Section 1-2

1.Formulate a hypothesis that might explain the presence of the “worms” in the container.

2.How could you test your hypothesis?

3. Identify the variables in your proposed experiment. Identify the control in your proposed experiment.

1–2 How Scientists WorkA. Designing an Experiment

1. Asking a Question

2. Forming a Hypothesis

3. Setting Up a Controlled Experiment

4. Recording and Analyzing Results

5. Drawing a Conclusion

B. Publishing and Repeating Investigations

1. Needham’s Test of Redi’s Findings

2. Spallanzani’s Test of Redi’s Findings

3. Pasteur’s Test of Spontaneous Generation

4. The Impact of Pasteur’s Work

C. When Experiments Are Not Possible

D. How a Theory Develops

Section 1-2

Section Outline

Designing an Experiment

Section 1-2

State the Problem

Form a Hypothesis

Set Up a Controlled Experiment

Record Results

Analyze Results

Draw a Conclusion

Publish Results

manipulated variable-variable that is deliberately changed

independent variable

responding variable-variable that is observed and that changes in response to the manipulated variable

dependent variable

Section 1-2

OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat.

HYPOTHESIS: Flies produce maggots.PROCEDURE

Controlled Variables:jars, type of meat,location, temperature,time

Manipulated Variables:gauze covering thatkeeps flies away from meat

Uncovered jars Covered jars

Several days pass

Maggots appear No maggots appearResponding Variable: whether maggots appear

CONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous generation of maggots did not occur.

Section 1-2

Figure 1-8 Redi’s Experiment on Spontaneous Generation Late 17th Century

Needham’s Experiment

Needham questioned Redi’s results and devised a test to prove that spontaneous generation could occur under the right conditions. He heated a sealed container holding gravy. He claimed that the heat would kill any “animalcules” that were living in it. After several days, the gravy was swarming with “little animals”.

Gravy is boiled. Flask isopen.

Gravy is teeming with microorganisms.

Gravy is boiled. Flask issealed.

Gravy is free of microorganisms.

Section 1-2

Figure 1-10 Spallanzani’s Experiment

Broth is boiled. Broth is free ofmicroorganismsfor a year.

Curved neckis removed.

Broth is teeming with microorganisms.

Section 1-2

Figure 1-11 Pasteur’s Experiment

Broth is boiled. Broth is free ofmicroorganismsfor a year.

Curved neckis removed.

Broth is teeming with microorganisms.

Section 1-2

Figure 1-11 Pasteur’s Experiment

Broth is boiled. Broth is free ofmicroorganismsfor a year.

Curved neckis removed.

Broth is teeming with microorganisms.

Section 1-2

Figure 1-11 Pasteur’s Experiment

Broth is boiled. Broth is free ofmicroorganismsfor a year.

Curved neckis removed.

Broth is teeming with microorganisms.

Section 1-2

Figure 1-11 Pasteur’s Experiment

Impact of Pasteur’s work related to microorganisms:

• French wine industry• Silk industry• Early research of infectious disease

Developing a Theory

As evidence from numerous investigations builds up, a hypothesis may become so well supported it is considered a theory.

A theory is a well-tested explanation that unifies a broad range of observations

Shells and Snowflakes

How can we distinguish between living and nonliving things, such as a radiolarian (left) and a snowflake (right)? A radiolarian is a tiny living thing that is covered with a glasslike shell and lives in the ocean. A snowflake is a crystal made of frozen water.

Section 1-3

Work with a partner to answer the following questions.

1.What are some similarities between the snowflake and the glass shell of the radiolarian?

2.What are some differences between the snowflake and the glass shell?

3.Would you classify the shell as a living thing or a nonliving thing? Explain your answer.

Section 1-3

1–3Studying LifeA. Characteristics of Living Things

1. Made Up of Cells

2. Reproduction

3. Based on a Genetic Code

4. Growth and Development

5. Need for Materials and Energy

6. Response to the Environment

7. Maintaining Internal Balance

8. Evolution

B. Branches of Biology

C. Biology in Everyday Life

Section 1-3

Section Outline

Video 1

Video 1

Video 2

Video 2

Characteristic ExamplesLiving things are made up of units called cells.Living things reproduce.

Living things are based on a universal genetic code.

Living things grow and develop.

Living things obtain and use materials and energy.

Living things respond to their environment.Living things maintain a stable internal environment.

Taken as a group, living things change over time.

Many microorganisms consist of only a single cell. Animals and trees are multicellular.Maple trees reproduce sexually. A hydra can reproduce asexually by budding.Flies produce flies. Dogs produce dogs. Seeds from maple trees produce maple trees.Flies begin life as eggs, then become maggots, and then become adult flies.Plants obtain their energy from sunlight. Animals obtain their energy from the food they eat.

Leaves and stems of plants grow toward light.

Despite changes in the temperature of the environment, a robin maintains a constant body temperature.

Plants that live in the desert survive because they have become adapted to the conditions of the desert.

Section 1-3

Characteristics of Living Things

Biosphere

Ecosystem

Community

Population

The part of Earththat contains allecosystems

Community and its nonliving surroundings

Populations thatlive together in a defined area

Group of organisms of onetype that live in the same area

Biosphere

Hawk, snake, bison, prairie dog, grass, stream, rocks, air

Hawk, snake, bison, prairie dog, grass

Bison herd

Section 1-3

Figure 1-21 Levels of Organization

Organism

Groups ofCells

Cells

Molecules

Individual livingthing

Tissues, organs,and organ systems

Smallest functionalunit of life

Groups of atoms;smallest unit of most chemicalcompounds

Bison

Nervous tissue Nervous systemBrain

Nerve cell

Water DNA

Section 1-3

Figure 1-21 Levels of Organization continued

Putting Size in PerspectiveHere are some measurements:A young child is just over 1 m in height. The marble in the child’s hand has a diameter of about 0.01 m. A cell in the palm of the child’s hand has a diameter of about 0.0001 m.

How can you put these numbers in perspective? You can use a ratio of the larger object to the smaller one. This requires dividing the larger number by the smaller number. Another way to compare these numbers is to look at the place value of the number 1. Each time the number shifts one place value to the right, it decreases by a factor of 10. Thus, 1 is ten times greater than 0.10, and 10 is one hundred times greater than 0.10.

Section 1-4

1–4 Tools and Procedures

A.A Common Measurement System

B.Analyzing Biological Data

C.Microscopes

1. Light Microscopes

2. Electron Microscopes

D.Laboratory Techniques

1. Cell Cultures

2. Cell FractionationE.Working Safely in Biology

Section 1-4

Section Outline

1. How does the height of the child compare to the diameter of

the marble?

2. How does the marble diameter compare to the diameter of the cell?

3. How does the height of the child compare to the diameter of the cell?

Section 1-4

Water Released and Absorbed by Tree

TimeAbsorbedby Roots

(g/h)

Releasedby Leaves

(g/h)

8 AM10 AM

12 PM2 PM4 PM6 PM8 PM

5

2

10149

641

1

12

17

16103

Water released by leaves

Water absorbed by roots

Rel

ati

ve

Rat

es

(g/h

)

20

Time

0

15

10

5

8 AM 10 AM 12 PM 2 PM 4 PM 6 PM 8 PM

Section 1-4

Analyzing Data

Microscopes

compound light microscope – produce magnified images by focusing visible light rays (1000X)

transmission electron microscope – shine a beam of electrons through a thin specimen

scanning electron microscope – shine a beam of electrons on the surface of a specimen

Section 1-4

Laboratory Techniques

Cell cultures – produce a group of cells from a single cell used for tests

cell fractionation – procedure used to separate out different cell parts for individual study

Section 1-4

Section 1 Answers

What other kinds of fossils have been found here? Is there evidence that a lake or inland sea existed in Wyoming at the time the fish lived here?

Students may not be able to suggest answers for all of their questions. Students may know that most fish fossils formed in layers of mud and sand, which is evidence that the area was once under water.

Scientists would have to dig to look for more fossils and catalog what is found in the same layers with the fish. Geologists would have to map the fossil deposit and look for evidence of a lake shore or inland sea.

1. Working with a partner, think of several questions that a scientist might ask in order to understand why there are fish fossils in the desert of Wyoming. Write these questions on a sheet of paper.

2. Discuss your questions with your partner, and suggest a possible answer to each question.

3. How could a scientist go about finding an answer to each of the questions?

Interest Grabber Answers

Section 2 Answers

Students may say that the “worms” are immature beetles, or that there might have been worm eggs or worms in the oatmeal.

If students thought that the worms were immature beetles, they may suggest isolating some of the worms to see if they develop into beetles. If students thought that there were eggs in the oatmeal, they may suggest taking a fresh sample of the oatmeal to see if worms hatch in it.

Student answers should indicate that the control remains unchanged and is a standard of comparison. Variables are the factors that are subject to change.

1. Formulate a hypothesis that might explain the presence of the “worms” in the container.

2. How could you test your hypothesis?

3. Identify the variables in your proposed experiment. Identify the control in your proposed experiment.

Interest Grabber Answers

Section 3 Answers

Interest Grabber Answers

Work with a partner to answer the following questions.

1. What are some similarities between the snowflake and the glass shell of the radiolarian?

2. What are some differences between the snowflake and the glass shell?

3. Would you classify the shell as a living thing or a nonliving thing? Explain your answer.

Both are tiny; both look crystalline.

Possible answer: The snowflake was not formed by a living thing, but the glass shell was.

Students will likely say that the shell is nonliving, although it once surrounded the living thing that formed it.

Section 4 Answers

Interest Grabber Answers

1. How does the height of the child compare to the diameter of the marble?

2. How does the marble diameter compare to the diameter of the cell?

3. How does the height of the child compare to the diameter of the cell?

The child’s height is 100 times the diameter of the marble.

The diameter of the marble is 100 times the diameter of the cell.

The height of the child is 10,000 times the diameter of the cell.

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