UNIT TWO: What is Science, The Scientific Method, and Characteristics of Living Things

1984

"No, they’re not real exciting pets- mostly they just lie around and wait to be fed-although a couple years ago Charles tried

teachin’ them to take a cookie from his mouth”

"Quit complaining and eat it!....Number one, chicken soup is good for the flu and number two , it’s nobody we know."

1986

O

0

u

Life on a microscope slide Another unsubstantiated photograph of the Loch Ness monster (taken by Reuben hicks, 5/24/84, Chicago)

Aaah! Look out everyone! It’s a

coverslip

Scientific investigations have actually concluded that chicken soup DOES improve flu symptoms! Living things eat/need energy!

Living things are made of cells! Is this scientifically testable “data”?

Introduction to Life Science Guided Reading and Study

What Is Science? This section describes the skills scientists use to learn about the world. The section also explains what life science is. Use Target Reading Skills Before you read, preview the red headings in your text. For each heading, write a what, how, or why question in the left-hand column below. As you read, write answers to your questions in the right-hand column.

Pgs. 6-13 in your textbook

Question Answer

What does observing involve? (This is an example of a question)

Observing involves….(not answer the question you asked on the left)

Scientific Skills

Not sure what

questions to ask? Try using &

answering the

“Reading Checkpoint” questions at the bottom of the page -OR- come

up with your own!

2

How do scientists (people, in general) learn about the world?

1. Observing-Using your sense(s) to gather _________________________

Quantitative Observations- observations based on ___or

- # of e-mails in your inbox

Qualitative Observations - observations based on . descriptions

- smell, taste, color preference, etc. 2. Inferring - Further explaining or interpreting an observation I Possible explanation for or _______________________ - Not a . - Based on logical reasoning - Not always correct - Example-you see a girl wearing a snowsuit….you can probably INFER that it is cold out (or in some of the science rooms in the other building)

- Example - you see a girl wearing a snowsuit. .. you can probably INFER that it is cold out (or she is in Mrs. Bartlett's classroom)

3. Predicting-

- Not always correct - Example - The weather will get colder as we approach winter

4. Classifying- Grouping together items - Example, socks go in the sock drawer

5. Making Models

-Creating of complex objects or processes to make them easier to understand

- Example, a globe

Life Science - The study of living (or once-living) things - Also known as biology

Biologists

Botanists

Geneticists

Ecologists

Microbiologists

Zoologists

- study .

- study .

- study .

- study .

- Study really small .

- study .

Section 1.1: What is Science (Pgs. 6-13 in your book)

- Making a forecast of what WILL happen in the _____________ based on past experience or evidence-

- Not a .

3

Introduction to Life Science Guided Reading and Study What Is Science? (continued) Introduction (Page 6 in your book) Is the following sentence true or false? Science is a way of learning about the natural world. .

1. What are five skills scientists use to learn more about the world?

Observing (page 7 in your book) 3. What is observing?

4. The senses a scientist uses in observing include sight, hearing, touch, taste, and _ _ .

5. In the spaces below, explain the differences between quantitative and

qualitative observations.

Inferring (Page 8 in your book 6. What is inferring?

Observations

Quantitative Observations Qualitative Observations

4

Introduction to Life Science • Guided Reading and Study

7. Circle the letter of each item that is true about inferences. a. Inferences are based on reasoning from what you already know. b. Making an inference involves wild guessing. c. An inference is an interpretation of observations. d. People make inferences all the time.

Predicting (Page 9) 8. Making a forecast of what will happen in the future based on

past experience or evidence is called _ . 9. How are inferring and predicting related?

Classifying (Page 10 in your book) 10. What is classifying?

11. Is the following sentence true or false? A drawback of classifying things is that objects and information stay disorganized .

Making Models (page 11 in your book) 12. What does making models involve?

13. Circle the letter of each item that could be a model. a. map b. movie set c. computer-generated illustration d. notebook notes

5

Introduction to Life Science • Guided Reading and Study What is Science? (continued) 14. Is the following sentence true or false? Models help people study things that cannot be

observed directly. .

15. Is the following sentence true or false? Some information about an object or process may be missing from a model. .

Working in Life Science (pages 12-13 in your book) 16. Life science is also known as _ _ Match the life-science career with its description. Career Description _______17. marine biologist a. determines which trees should be cut

b. studies plants and may work with farmers c. studies living things found in oceans _______18. forestry technician

_______19. botanist

6

Introduction to Life Science • Laboratory Investigation Using Scientific Inquiry to Investigate Potato Sprouting Problem How can you use the process of scientific inquiry to investigate whether light is necessary to the sprouting of a potato? Skills Focus observing, controlling variables, interpreting data, drawing conclusions

Materials 1 medium-sized potato, 2 plastic bags with Ziplocs, 2 paper towels, marker pen , Procedure Review the safety guidelines in Appendix A of your textbook 1. With members of your group, discuss whether a potato needs light to sprout.

Based on your discussion, develop and record a hypothesis. 2. Use the marker pen and tape to label one plastic bag as Potato A and the other

plastic bag as Potato B. Also, use the marker pen to write the name of your group on each bag. Keep in mind that you will be making your observations through the bag; make sure your labels will not block your observations.

3. Fold each paper towel repeatedly until you have a rectangle about the same size as your potato halves. Moisten the towels with water. Place a folded towel in each plastic bag.

4. Carefully cut the potato in half lengthwise. Place a potato half in each plastic bag, with the cut surface of the potato on the paper towel.

5. Tie each bag with a twist. Each bag should look like the illustration on this page.

I think….

because….

Potato half

Ziploc

Potato Eyes

Plastic Bag

7

7. Place Potato A in a place that receives light. Place Potato B in a dark place that receives little or no light. Be sure that the potato halves remain on top of the paper towels and that both potato halves are kept at the same temperature.

8. After 1 week, count the number of sprouts on each potato half. Record these data in the Data Table.

Analyze and Conclude

1. What was the manipulated variable and the responding variable in this experiment?

2. What variables were kept constant in this experiment?

Introduction to Life Science • Laboratory Investigation 6. Count the number of eyes on each potato half. Record the number of

eyes or sprouts, if any, in the Data Table. Data Table

3. Which potato had a greater percentage of sprouts-the potato kept in the dark or on the potato that received light?

4. Did your results support or disprove your hypothesis? Explain.

Potato

Number of Eyes

Number of Sprouts Week 1 Week 2

Potato A (light)

Potato B (dark)

Answ

er th

ese

ques

tions

thr

ough

8, t

hen

1-7

in 1

wee

k, n

ot fi

rst d

ay o

f la

b!!!

!!

8

6. Why were the plastic bags sealed?

Introduction to Life Science • Laboratory Investigation Using Scientific Inquiry to Investigate Potato Sprouting (continued) Critical Thinking and Applications 5. Why was it important to keep both Potato A and Potato B at the

same temperature throughout the experiment?

7. Would your experimental results be enough to develop a scientific theory about potato sprouting? Explain.

Answ

er 5

-7 in

1 w

eek,

not

firs

t day

of l

ab!!

!!!

9

Animal A

Section 1 Section 2 Section 3

2. How many types of animals made the tracks shown in the illustration? What observations give you the answer?

3. What inferences, if any, can you make about the relative sizes of the animals?

4. What do you think happened in Section 2?

5. What inference can you make based on the tracks in Section 3?

Introduction to Life Science • Enrich

A Tale Told by Tracks In a park on a chilly winter day, you see mysterious animal tracks in the snow, as shown in the illustration below. The illustration has been divided into three sections. Look at these tracks carefully, and use your observations to make inferences about the animals .

Data Table

Section Observations Inferences

1

2

3

1. In the data table below, write observations of the tracks in each of the three sections of the illustration. Then write any inferences that you can make about the tracks in each section.

Answer the following questions in the space provided by the question

10

Introduction to Life Science • Review and Reinforce

What ls· Science? Building Vocabulary Match each term with its definition by writing the letter of the correct definition on the line beside the term in the left column.

a. the process of grouping together items that are alike in some way

b. . making a forecast of what will happen in the

future based on experience or evidence c. creating representations of complex

objects or processes

d. the study of living things

e. . explaining or interpreting things you observe

f. observations that deal with descriptions that cannot be expressed in numbers

g. a way of learning about the natural world h. using one or more of your senses to gather

information

i . observations that deal with a number, or I amount

1. observing

2 . quantitative observations

3. qualitative observations 4. inferring 5. predicting

6. making models

7. classifying

8. science

9. life science

11

Have you ever wanted tofind out the answer to a problem? Of course you have! Ifyou took the time to solve your problem, you probably used the Scientific Method without even knowing it! What's the Scientific Method, you ask? It's using the skills of thinking, questioning, reasoning, inquiring, testing, explaining, and analyzing to solve a problem. Here are the steps:

What is the best setting on my toaster for toasting a frozen waffle so that it is warm throughout, but not burnt?

Make a HYPOTHESIS Predict WHAT you think will happen and WHY (I think... because...) OR “If. . .then...because”

I think I will turn the dial to the middle setting because the low setting probably won't

defrost it, but the high setting will probably burn it

TEST your hypothesis

Put your waffle in the toaster on the middle setting

ANALYZE your results

Determine whether the waffle is uniformly warm; is the center still frozen? Check all sides of the waffle for burning/charring; is there any?

REPLICATE Replication helps to ensure that your results are more accurate.

Perform the test again. Make sure you put the waffle in the same slot in the same

position. You should also wait until the toaster has cooled down completely so that the testing conditions are as close to the conditions of the original test. If they're not, you may end up with different results because you did not control enough of the variables

(factors that might influence or change the results of the test)

Because the middle toaster setting leaves the center of the waffle frozen, it is not the best

setting for toasting uniformly warm, non-burnt waffles.

INQUIRING MINDS WANT TO KNOW ...

What's the Scientific Method?!?!?!?!?

Determine your PURPOSE and PROBLEM

Form a CONCLUSION

12

13

14

Concept Mapping: The Scientific Method Fill in the concept map to show the steps commonly used in the scientific method. Use the following words/ phrases in the box below…only use the word once:

Perform the Experiment (Test), Replicate, Purpose/Problem, Conclude or Conclusion, Analyze, Hypothesis

Know for Test

15

Introduction to Life Science • Guided Reading and Study

Scientific Inquiry (pages 14-18 in your book) This section explains what a process called scientific inquiry is and what makes an explanation called a hypothesis testable. It also describes attitudes that successful scientists have. Use Target Reading Skills A definition states the meaning of a word or phrase by telling about its most important feature or function. After you read this section, reread the paragraphs that contain the definitions of the Key Terms. Use all the information you have learned to write a definition of each Key Term in your own words on the lines below. scientific inquiry

hypothesis

variable

controlled experiment

manipulated variable (independent variable)

responding variable (dependent variable)

operational definition

data

communicating

16

Introduction to Life Science • Guided Reading and Study

Scientific Inquiry (continued) life science

The Scientific Process (Pgs. 14-17 in book) 1. What does scientific inquiry refer to?

2. Is the following sentence true or false? Scientific inquiry often begins with developing a hypothesis. _ __ ___

3. Circle the letter of each sentence that is a scientific question.

a. At what temperature does water boil? b. When does the sun rise on April 3? c. How can my team work better together? d. Why does she like science more than he does?

4. A(n) is a possible explanation for a set of observations or answer to a scientific question.

5. Is the following sentence true or false? Scientists consider a hypothesis to be a fact. _ __ _

6. What is a testable hypothesis?

17

Introduction to Life Science • Guided Reading and Study 7. To test a hypothesis, a scientist designs a(n) __ Match the term with its definition. Term Definition

a. a statement that describes how to measure a particular variable or define a particular term

b. the one variable that is purposely changed to test a hypothesis

c. a factor that can change in an experiment

d. the factor that may change in response to the manipulated variable

e. an experiment in which only one variable is manipulated at a time

8. responding variable (Dependent)

9. operational definition

10.Manipulated var iab le

(independent) 11. controlled

experiment

12. variable

13. Is the following sentence true or false? If you did not control variables in an experiment, there would be no way to know which variable explained your results. .

14. In carrying out a controlled experiment, what does an operational definition do?

15. The facts, figures, and other evidence gathered through observations are called __

16. Circle the letter of each sentence that is true about graphs .

a. A graph can reveal a trend in data. b. Graphs are the only way to organize data. c. A graph can reveal a pattern in data.

17. A(n) _ _ is a summary of what you have learned from an experiment.

18. What do you ask yourself in drawing a conclusion about an experiment?

______

______

______

______

______

18

Building Vocabulary Fill in the blank to complete each statement .

23. A(n) . is a possible explanation for a set of observations or an answer to a scientific question.

24. Factors that can change in an experiment are called .

25. The sharing of ideas and experimental findings with others through writing and speaking

is called .

26. The study of living things is called life science, or .

27. Facts, figures, and other evidence gathered through observations are called

.

28. The factor that may change in response to the manipulated variable is called the

_

29. An experiment in which only one variable is manipulated at a time is called a(n)

_______________________ experiment.

30. The process of ________________________ refers to the diverse ways in which scientists study the natural world and propose explanations based on the evidence they gather.

31 A(n) ___________________________ is a statement that describes how to measure a

particular variable or define a particular term.

32. The one variable that is purposely changed to test a hypothesis is called the

________

Introduction to Life Science • Guided Reading and Study

Scientific Inquiry (continued) Complete the Nature of Inquiry diagram by filling in the blanks. The Nature of Inquiry 22. Why is scientific inquiry a process with many paths, not a rigid sequence of steps?

19

Section 1.2: Scientific Inquiry ( pgs. 14-18 your book)

The Scientific Method I Process -the ways in which scientists study the natural world and propose explanations based on gathered evidence

Paul’s

Hairy

Teeth Controlled Experiment - Only one variable is being tested at a time

- Factors that can be changed in an experiment (ex. air temperature, type of cricket, type of container, type of thermometer)

- Good experiments test ONLY ONE variable at a time

Manipulated/ _ - The variable being changed so that its

1. _ _ - basis for the investigation

"Is the temperature of the air related to the chirping of crickets?"

2. HYPOTHESIS- _ _ what may be learned from the investigation and why

Must be testable; the evidence must either support of disprove it "I think warm temperatures may cause crickets to chirp faster because they seem to chirp more on very hot nights and less on cool nights."

3. _ -performing the investigation and collecting data

Variable

effects (or lack of) can be tested - Example - air temperature

Responding/ - The variable that MAY change in Variable response to the Manipulated I Independent

Variable - Example -number of cricket chirps

- the facts, evidence and information gathered through your observations and experimentation

- interpreting the data to reveal patterns or are trends in the data and/or to simplify the data and make better sense of it

Creating a bar graph that compares temperature to number of chirps

4. Are

20

5. REPLICATE . Really

6. CONCLUDE- a summary statement of _ _ from your experiment

- May or may not match I support the original hypothesis; fine either way

- May lead to a - a broad explanation derived from MANY hypothesis, experiments, and conclusions

"The warmer the temperature of the air, the faster crickets will chirp."

Other Important Parts of Science (DON'T memorize for test)

7. Communicating / Sharing Information (no need to reinvent the wheel)

8. Curiosity ( eagerness to learn more)

9. Honesty (otherwise you'll be known as the boy who cried wolf)

10. Open-Mindedness (sometimes things aren't always as they seem)

11. Skepticism (don't assume something is correct just "because")

12. Creativity (don't be afraid to try things a new way and invent)

Cool

21

Procedure : Review the safety guidelines in Appendix A. 1. You have just been given a bouquet of cut flowers. You remember once

seeing a gardener put some sugar into the water in a vase before putting flowers in. You wonder if the gardener did that so that the flowers would stay fresh longer. Write a hypothesis for an experiment you could perform to answer your question. I think ...

because… 2. Working with your lab group, design a controlled experiment to test your

hypothesis. Brainstorm a list of all the variables you will need to control. Also decide what data you will need to collect, For example, you could count the number of petals each flower drops. ·

Introduction to Life Science • Design Your Own Lab

Keeping Flowers Fresh Problem How can cut flowers stay fresher for a longer time? Skills Focus developing hypotheses, designing experiments, drawing conclusions

Materials

plastic cups ruler

cut flowers tape

spoon scissors

water cup

sugar

Variables you need to control: What must stay the same?

3. Write your period number and group initials (Each of your first intitial and last initial) on each cup. Label one cup “plain water”. Label the other cup “sugar water”

4. DON’T FORGET to clean up!!!!! Wipe up sugar and water that may have spilled.

22

Data you need to collect (How will you know which plant is growing better? How will you measure? Day 1 Day 2

Day 3

Day 4 Day 5 _________________________________________________________________________________

_________________________________________________________________________________

Keeping Flowers Fresh Lab (continued)

Write down the manipulated variable (What are you changing?) PLAIN WATER vs.

Write down the responding variable (write down what effect the manipulating variable has on the flowers)

ANALYZE and CONCLUDE (This section will be answered over several days) 1. Developing Hypotheses: What hypothesis did your decide on to test? On what information or experience was your hypothesis based? 2. Designing Experiments: What was the manipulated variable in the experiment you performed? What was the responding variable? What variables were kept constant?

23

What are your steps?

(If necessary, revise your plan according to any teacher’s instruction or help THEN set up and begin your experiment TODAY!!!!)

Scientific Method Bikini Bottom Experiments

The Bikini Bottom gang loves science class and wanted to do a little research. Read the description for each experiment and use your knowledge of the scientific method to answer the questions. (1) Flower Power

SpongeBob loves to garden and wants to grow lots of pink flowers for his pal Sandy. He bought a special Flower Power fertilizer to see if will help plants produce more flowers. He plants two plants of the same size in separate containers with the same amount of potting soil. He places one plant in a sunny window and waters it every day with fertilized water. He places the other plant on a shelf in a closet and waters it with plain water every other day. What did SpongeBob do wrong in this experiment? Explain.

What should SpongeBob do to test the effectiveness of Flower Power fertilizer? Write an experiment.

(2) Super Snails Gary is not the smartest snail in Bikini Bottom and believes he can improve his brain power

by eating Super Snail Snacks. In order to test this hypothesis, he recruits SpongeBob and several snail friends to help him with the experiment. The snails ate one snack with each meal every day for three weeks. SpongeBob created a test and gave it to the snails before they started eating the snacks as well as after three weeks. Based on the data provided in the table below, do the Super Snail Snacks work? Explain your answer.

Test Results Snail Before After

Gary 64% 80%

Larry 78% 78%

Barry 82% 84%

Terry 72% 70%

24

Scientific Inquiry and Brine-Shrimp Eggs Scientific inquiry involves different processes, such as posing questions, developing hypotheses, performing experiments, and interpreting data. A scientist was studying brine shrimp, which are tiny animals that live in salt water. The scientist wondered whether the temperature of the water affects the time it takes for brine-shrimp eggs to hatch. The scientist performed an experiment to find the effect of temperature on brine-shrimp eggs. In the experiment, one group of eggs was in water that had a temperature of 30°C. A second group of eggs was in water that had a temperature of 22°C, and a third group was in water at l5°C. The graph below shows the data that the scientist collected. Study the graph, and then answer the questions below in the space provided next to the question

Effect of Temperature on the Development of Brine-Shrimp Eggs

1. What question did the scientist pose?

2. What was the manipulated variable in the experiment that the scientist performed? 3. What was the responding variable in the experiment? 4. How long did the brine-shrimp eggs take to hatch at 30°C? How long did the eggs take to hatch at l5°C? 5. What do the data show about the effect of temperature on the time brine shrimp eggs take to hatch? 6. Suppose that, before the experiment, the scientist proposed the following hypothesis: Temperature has no effect on the time brine-shrimp eggs take to hatch. Do the data support this hypothesis? Explain why or why not.

7. Predict how long brine-shrimp eggs would take to hatch in water that had a temperature of 20°C.

25

Introduction to Life Science • Key Terms

Key Terms

Answer the questions by writing the correct Key Terms in the blanks. Use the numbered letters in the terms tofind the hidden Key Term. Then write the definition for the hidden Key Term. Clues Key Terms

1. The one variable that is purposely changed to test a hypothesis

1 2. A way of learning about the world

2 3. The sharing of ideas and experimental findings

with others 3

4. A possible explanation for a set of observations or an answer to a scientific question

4 5. An explanation or interpretation of the things

you observe 5

6. Type of experiment in which only one variable is manipulated at a time

6 7. Creating representations of complex objects or

processes

8. Type of definition that describes how to 7

measure a variable or define a term 8

9. A person who is trained to use both technological and scientific knowledge to solve practical problems 9

10. The process of grouping together items that are alike in some way

Key Term __ __ __ __ __ __ __ __ __ __ 1 2 3 4 5 6 7 8 9 10

__ __ __ __ __ __ __ __ __ __ __ __ __

__ __ __ __ __ __ __ __ __ __ __

__ __ __ __ __ __ __ __ __ __

__ __ __ __ __ __ __ __ __

__ __ __ __ __ __ __ __ __ __

__ __ __ __ __ __ __ __ __ __ __

__ __ __ __ __ __

__ __ __ __ __ __ __ __

__ __ __ __ __ __ __

__ __ __ __ __ __ __ __ __ __ __ 10

E N G I N E E R

O P E R A T I O N A L

C L A S S I F Y I N G

O G Y

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Organisms Characteristics of Living Things (ALL must be present or the "creature" is NOT living)

1. Made of Cells No cells, no life _ -an organism made of just 1 cell - Example - bacteria - Most numerous form of life on Earth _ -an organism made of many cells that are specialized to do different jobs (ie. muscle cells, nerve cells, skin cells)

2. Are made of Chemicals

- The chemicals make up the cells - water (most prevalent)

3. Use _____________________ - Needed for repairing injured cell parts - - Needed to do work

4. ___________________ - Organisms REACT to their environment - Example-plants bend toward the light - ______________________ - thing that causes the reaction (sunlight) - _______________________ - the reaction to the stimulus (bending)

5. Grow & Develop - Growth -the process of getting ____________

- Development- the process of change that occurs over a lifetime resulting in a _ __ well-adapted organism

6. __ - produce offspring that are similar to the parents

SECTION 2.1: What is Life? (34-40 your book)

- ________________(energy source) - ________________ (join together with lipids to make cellular structures) - ___________________ (fats, also join with proteins) - ___________________ (make up the instructions for making new cells…in other words, genetic material).

27

Life Comes From Life - Living things come from living things through reproduction

- The MISTAKEN idea (400 years ago, but lasted for a couple hundred years) that living things could grow from non-living things ' - Example - Maggots come from rotting meat or baby mice come from rags in the bam

Attempts to disprove Spontaneous Generation

1. Francesco Redi - 1600's - Doctor who decided to prove that flies do - - - NOT come from rotting meat - Independent Variable- _ _ - Dependent Variable- _ - Conclusion- Rotting meat does not produce flies - See Redi’s Experiment picture on next page

2. Louis Pasteur - mid-1800's - Chemist who decided to prove to the skeptics, once and for all, that life does NOT come from non-life - proved that bacteria ONLY grows in broth that already contains bacteria but NOT in sterile broth - See the Pasteur's Experiment pictures on next page

What living things need

1. needed to absorb nutrients, break down food, grow, move substances within their bodies, and sometimes to reproduce

2. Food - needed as an energy source - ____ make their own food (self) (feeder) - - cannot make their own food, (other) (feeder) thus eat autotrophs or other

heterotrophs that have eaten autotrophs

3. Living Space - a place to get food and water and shelter

4. Stable Internal Conditions

the term for the maintenance of a stable internal environment

- Must be able to stabilize conditions in their body even though the external environment may change

- Example- body temperature, heart beat, sweating

28

29

30

Rejecting Spontaneous Generation Four hundred years ago, people believed in spontaneous generation- the idea that life could appear from nonliving material. The scientists Francesco Redi and Louis Pasteur designed controlled experiments to reject the idea of spontaneous generation. Redi's Experiment Francesco Redi showed that flies do not spontaneously arise from decaying meat. He designed one of the first controlled experiments. In a controlled experiment, a scientist carries out two tests that are identical in every aspect except for one factor, called the manipulated variable. Set up and run the experiment.

1. In what way was Redi's experiment "controlled?"

2. What were Redi's independent and dependent variables? Pasteur's Experiment By Louis Pasteur's time, controlled experiments were standard procedure. By carefully controlling whether or not bacteria could enter a flask, Pasteur proved that bacteria arise only from existing bacteria.

Pasteur put clear broth into two flasks with curved necks. The necks would let in oxygen but keep out bacteria from the air. Pasteur boiled the broth in one flask to kill any bacteria in the broth . He did not boil the broth in the other flask.

In a few days, the unboiled broth became cloudy, showing that the new bacteria were growing. The boiled broth remained clear. Pasteur concluded that bacteria do not spontaneously arise from the broth. The new bacteria appeared only when living bacteria were already present.

Later, Pasteur took the flask containing the broth that had remained clear and broke its curved neck. Bacteria from the air could now enter the flask. In a few days, the brothe became cloudy. This evidence confirmed that new bacteria appear only when they are produced by existing bacteria.

1. In what way was Pasteur's experiment "controlled?"

2. What were Pasteur's independent and dependent variables?

Presentation Express CD: Active Art- Redi and Pasteur PHSchool.com code: cep-1011

31

Living Things • Guided Reading and Study

What is Life? (Pages 34-40 in your book)

This section explains the characteristics of living things and what living things need to survive

Use Target Reading Skills Look at the section headings and visuals to see what this section is about. Then write what you already know about living things in the graphic organizer below. As you read, write what you learn. The Characteristics of Living Things What is an organism? ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________

What You Know (You may write more than 2)

(Example)…Living things Grow 1. 2.

What You Learned (You may write more than 2)

(Example)…Living things Grow 1. 2.

32

2. List six characteristics that all living things share.

a.

b.

c.

d.

e.

f. 3. The basic building blocks of all organisms are _ _

4. Is the following sentence true or false? Most cells can be seen only with a

microscope, a tool that magnifies small objects.

5. Is the following sentence true or false? An organism made of many cells is a unicellular organism. _ _ _

6. Circle the letter of the most abundant chemical in cells.

a. proteins b. carbohydrates c. water d. nucleic acids

7. Lipids and are the building materials of cells.

8. Is the following sentence true or false? The cells of organisms use energy for growth and repair. _ __

9. Circle the letter of a change in an organism's surroundings that causes the organism

to react. a. growth b. response c. stimulus d. development

Living Things • Guided Reading and Study What Is Life? (continued)

33

Living Things • Guided Reading and Study 10. Give one example of a stimulus and one example of a response.

Stimulus:

Response: . 11. What is development?

12. All organisms can , or produce offspring that are similar to the parents.

Life Comes From Life 13. Is the following sentence true or false? Flies can arise from rotting meat.

14. The idea that living things can come from nonliving sources is called

15. What did Francesco Redi show in his experiment?

' 16. The factor that a scientist changes in a controlled experiment is the

17. Is the following sentence true or false? Louis Pasteur used a controlled experiment to show that bacteria arise from spontaneous generation.

34

Living Things • Review and Reinforce

What Is Life? Building Vocabulary From the list below (16 different vocab words), choose the term that best completes each sentence.

autotrophs unicellular spontaneous generation response

manipulated variable Heterotrophs multicellular homeostasis

cell organisms stimulus reproduce

1. A change in an organism's environment that causes the organism to react is called a(n)

_ _

2. Organisms that make their own food are _

3. ______________________________ organisms are composed of many cells. 4. ______________________________ is the mistaken idea that living organisms areise from

nonliving sources.

5. Living things are also called ____________________________.

6. The ____________________________ is the basic unit of structure in an organism.

7. Organisms that get energy by consuming other organisms are _________________________.

8. An organism ability to maintain stable internal conditions is called

______________________. 9. A controlled experiment is conducted by performing two tests that are identical except for one

factor called the __________________________________. 10. To ______________________________________ is to produce offspring that are similar to the parents. 11. Bacteria, the most numerous organisms on Earth, are ____________________organisms.

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Living Things • Enrich

Bacteria Counts Many scientists use bacteria in the course of their research. They must provide the bacteria with the proper conditions for growth.

This is how one laboratory grows bacteria. A certain amount of bacteria are placed into a solution of water and nutrients the bacteria need as an energy source. After a period of a few days, a small amount of this solution is poured onto a petri dish, a shallow, round container with a cover, made from transparent plastic . Inside the petri dish is a layer of agar, usually a gelatin-like material that also contains nutrients and on which bacteria can grow. The petri dishes are then put in a warm, moist place for a week. After a week, the bacteria on each dish are counted. To do this, the scientist places each dish under a large magnifying glass that has a grid similar to graph paper drawn on it. She/he then counts the number of spots of bacteria growing on the agar in each of the squares on the grid. The individual bacterium is not counted; rather, each spot is actually a colony of bacteria. The scientist knows approximately how many bacteria are in a colony, so once she knows the number of colonies growing on a petri dish, she/he can calculate the number of bacteria present.

Here are the drawings one of the scientists made in her laboratory notebook of the petri dishes she/he examined. She/he has also noted the conditions the bacteria were grown in next to each drawing. Study the drawings and the information next to each dish. Consider the growing condition for each dish, then try to explain why the bacterial appeared as they did under each petri dishes explanation.

Explanation Explanation

Explanation Explanation

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Bubble Time Patrick loves bubble gum and would like to be able to blow bigger bubbles

than anyone else in Bikini Bottom. To prepare for the Bikini Bottom Big Bubble

Contest, he bought five different brands of bubble gum and needs your help to find

the brand that creates the biggest bubbles. Write an experiment to test the bubble

power of the bubble gum brands and help Patrick win the contest.

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