TAKS Objective #1

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The student will demonstrate an understanding of the nature of science. TAKS OBJECTIVE #1

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TAKS Objective #1. The student will demonstrate an understanding of the nature of science. Safety. 1. Always obtain the instructor’s permission before beginning a lab. 2. Read the procedure (more than once) before beginning the experiment. Ask the instructor if you have any questions. - PowerPoint PPT Presentation

Transcript of TAKS Objective #1

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The student will demonstrate an understanding of the nature of science.

TAKS OBJECTIVE #1

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SAFETY

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1. Always obtain the instructor’s permission before beginning a lab.

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2. Read the procedure (more than once) before

beginning the experiment. Ask the instructor if

you have any questions.

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3. Always wear safety goggles.

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4. Always point the

mouth of a test tube

away from yourself and

others.

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5. Never eat or drink anything in the lab.

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6. Remember if you need to smell a substance, waft

it toward your nose. Do not

directly smell the chemical.

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7. When diluting an acid, always pour the acid into

the water.

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8. Reactions that produce toxic fumes should be performed

under a fume hood.

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9. Know the location of all the safety equipment in

the lab.

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10. Long hair, loose clothing, and jewelry should be

secured and tied back during lab procedures.

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11. Do not handle hot or cold containers with your bare

hands.Use the proper holder for the

container.

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12. Report any and all accidents to the teacher

immediately, no matter how big or small.

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13. Ask the teacher for the proper way to dispose of

any material.

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1. A science class is conducting an experiment that produces noxious fumes. Because of inadequate ventilation, some students begin to feel nauseated and dizzy. The first response should be to —

A neutralize the acid that is reacting to produce the noxious fumesB carry the reactants outside, away from other studentsC leave the room and go to an area with fresh airD spray the reaction with a fire extinguisher

Not A – Acids are not the only producers of fumes, and adding something else could make it worse!

Don’t move it anywhere except under a fume hood, Too dangerous! Not B

Not D --Extinguishers should only be used on fires.

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2. The safest way to dilute concentrated sulfuric acid is to add —

A a series of small volumes of water to the acid while stirring

B the acid to water slowly while stirring constantly

C the acid to a small volume of water and then add more water

D dilute sulfuric acid to a small volume of the concentrated acid

The safety rule says always add acid to water, so A & C are out since they both add water to acid.

D doesn’t even make sense since you can’t make concentrated acid out of a dilute acid by adding to it.

So the answer is

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3. If there is a clear chemical on your table during a lab, how should you identify it?

A. Ask your instructor what it is.B. Taste the chemicalC. Smell the chemicalD. Rub the chemical between your fingers

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4. You should report a cut in your skin, glass breakage, or chemical spillA. after the problem is handledB. neverC. immediatelyD. after you write down what happened

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5. Which is the correct way to hold a test tube while heating its contents?A. pointing straight upB. Pointing horizontallyC. Pointing away from yourself and othersD. Pointing straight at yourself

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6.

Answer: D

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7.

Answer: A

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SAFETY SYMBOLS

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BiohazardBiological

materials that could be harmful.

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Toxic or Poisonous

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CorrosiveCorrosive means

capable of destroying or

eating away by chemical means.

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FlammableEasily set

on fire.

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Safety GogglesGoggles MUST be

worn at all times while in the lab.

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Open Flame AlertBe careful when using an open

flame as an explosion could occur.

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LAB EQUIPMENT

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BeakerA beaker is used to hold

liquids.

It is not precise enough to make good

measurements.

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Graduated CylinderUsed to measure

liquid volumes (mL).

Always read a graduated cylinder from the bottom of

the meniscus.

meniscus

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PipettePipettes are used to

measure small amounts of liquid.

They are very precise.

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Which would be most precise?

Pipette

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Test TubeA test tube is used to hold or store liquids.

It is not a precise measuring instrument.

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Test Tube Rack A test tube rack is used to hold and support test tubes.

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Test Tube Clamp

Test tube clamps are used to hold a test tube while its contents are being heated.

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Triple Beam Balance

A triple beam balance is used to measure mass (kg).

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FunnelA funnel is used to transport materials from one container into another container.

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Erlenmeyer FlaskAn

Erlenmeyer flask is used to hold and

mix liquids.

It is not precise.

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Ring Stand

A ring stand is used to hold objects.

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Bunsen BurnerA Bunsen burner uses natural gas to provide a heat source.

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TongsTongs can

be used when

handling hot or cold

objects, such as beakers.

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ACCURACY & PRECISION

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Accuracy & Precision Accuracy = refers to how “correct” the answer is (hitting the bull’s eye)

Precision = refers to how small a scale is being used to make a measurement or how close measurements are to each other.

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Accuracy This is when a measurement is closest to its true value.

The exactly correct answer.

The bull’s eye.

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Precision This is the repeatability of a measurement.

It may or may not be accurate

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Precise, but not accurate.

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Accurate and precise.

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Not accurate or precise.

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A B

C DA=high precision, high accuracy

B=low precision, high accuracy

C=high precision, low accuracy

D=low precision, low accuracy

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Learning Check

1. Consider this: if you had two beakers, one labeled in 1mL increments and the other labeled in 10 mL increments, which would give you a more precise measurement?

A. The one labeled in 10 mL increments

B. The one labeled in 1mL incrementsC. NeitherD. Either

Answer: B the one labeled in 1 mL increments

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2. Which of the following measurements is most precise?

A. 2.8623cm B. 2.8cm C. 2.87cm D. 2cm

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3. Which of the following is most precise?

A. 31/4 in. B. 3 1/16 in.C. 3 in.D. 31/32 in. Answer: D

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4. A student measured the length of a piece of string that was 64.34 cm. long. Her measurements were 67.02 cm, 67.07 cm, 67.05 cm, and 67.04 cm. Which statement is true?

A. The measurements were accurate but not precise.

B. The measurements were precise but not accurate

C. The measurements were both precise and accurate

D. The measurements were neither.Answer: B

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5. Which of the following will allow measurement of a liquid’s volume with the greatest precision?

A 50 mL cylinder graduated in 1 mL increments

B 50 mL cylinder graduated in 0.5 mL increments

C 100 mL cylinder graduated in 1 mL increments

D 200 mL cylinder graduated in 5 mL increments

Answer: B

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6. Four lab groups measured the volume of acid required to neutralize a standard solution of sodium hydroxide base. Which of the groups

measured the volume with the highest precision?

D is the best choice as the small volume markings on the burette gives the most precise measurement.

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MEASUREMENT

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Scientific Measurement - SI UnitsSI units are the basis for measurement

world-wideThey are used so that no matter which

country a scientist is working in, he or she can relate their findings to another scientist accurately.

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Tools for Measurement

• Clocks and stopwatches measure time.

• A balance is used to measure mass.

• A graduated cylinder, dropper, or Erlenmeyer flask is used to measure

volume.

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LengthThe standard unit of

measurement to determine length is a meter (m).

It measures the distance from one point to another.

A ruler or meter stick are most commonly used to determine length.

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MassMass is the measure of the amount

of matter an object has.It is measured in grams (g).The tool for measuring mass is the

triple beam balance.

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VolumeVolume is the amount of

space occupied by an object.

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VolumeThe units for volume are cubic

centimeters (cm3) or milliliters (mL).

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VolumeThe volume of a regular object

can be determined mathematically.

For example, the volume of a cube is length x width x height.

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Volume

The volume of irregular objects can

be determined

by displaceme

nt.

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DensityDensity is the mass of an object divided by its volume.

It is measured in g/cm3.Density helps explain why things float.

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TemperatureTemperature measures how hot or

cold something is.All measurements for temperature

are taken in degrees Celsius.The SI unit for temperature is Kelvin (K).

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TemperatureA thermometer is the most common tool for measuring

temperature.

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1.

144.1 grams

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Learning Check

2. We measure mass is in?

3. We measure volume in?

4. We measure length in?

A. Grams

B. Meters

C. Liters

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5.

What is the volume of the liquid

in the graduated cylinder?

Answer: 43 mL

meniscus

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What is the reading on the pipette?

Answer: 19.4

6.

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TAK Obj. 01TEKS B.2B

47

38

Answer: 47-38 = 9 mL

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8. Which piece of equipment would be the most appropriate for measuring the volume of a marble.

A. B. C.

Answer: graduated cylinder - A

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Answer: C

9.

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CONVERSIONS

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Converting SI unitsRemember:

Kevin Has Diarrhea U Don’t Call Mom!!

K H D(da) u d c m

Move the decimal point the correct number of spaces in the proper direction!

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For example: 2L = ? mL1 2 3

Step #1 k h da u d c m

(remember that u = meters, liters & grams)Step #2 – determine how many spaces are between u and mStep #3 – move the decimal in the original problem the same number of spaces and in the same direction for your answer.

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Therefore 2L = 2000mLRemember to move the decimal the same direction that you moved on the chart!!

2 0 0 0

1 2 3

. .

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Practice problems

1. 35 hg = ? dg

2. 2.56 kg = ? cg

3. .065 mL = ? hL

Answer: 35,000 dg

Answer: 256,000 cg

Answer: 0.00000065 hL

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SCIENTIFIC METHOD

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How Do Scientists Solve Problems?

The Scientific Method

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1. Make an observation.

Use your senses (sight, hearing, touch, etc.) to make

observations.

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2. Ask a question. Ask a question and begin

identifying the problem.

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3. Form a HypothesisA hypothesis is an

educated guess. It must be testable.

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4. Conduct an Experiment

Design and conduct an experiment to test your

hypothesis.

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5. Record and Analyze the Data

Record and organize the data from the experiment.

Analyze the results so that a conclusion can be formed.

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6. Make a ConclusionAfter analyzing

your results, make a

conclusion.Determine if your hypothesis

was right or wrong.

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Scientific TheoryTheories are based upon experimental data.

Confirmed by repeated experiments.

Modified as new information is gathered.

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Scientific Law

Theories become Laws when nothing changes for hundreds of years.

Laws become theories again when new information changes them.

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#1

Answer: C

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TAK Obj. 01TEKS I.3B

Answer: C

#2

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TAK Obj. 01TEKS B.2A

Answer: A

#3

A

B

C

D

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Answer: A

#4

A

B

C

D

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Answer: D

#5

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Answer: A

#6

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Answer: A

#7

A

B

C

D

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Answer C

#8

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EXPERIMENTS

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The Independent Variable is the variable that can be

manipulated or changed by the scientist.

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The Dependent Variable is the variable that changes because of

the independent variable. It must be measured, counted, or

observed.

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The control is the part of the experiment that is held constant. It is used for

comparison.

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The factors that must remain the same in each experimental setup

are the constants.

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ExperimentingYou are planning to grow tomatoes in your garden, but you don’t know what the best kind of fertilizer would be. At Wal-Mart you find 3 different fertilizers for tomato plants.

Design an experiment to test which fertilizer is best.

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What would the independent variable be?The type of fertilizer

What would the dependent variable be?The growth of the tomato plants and the

amount of fruit they produce.What is the control?

The control would be the plants where NO fertilizer was added.

What are the constants?The constants could include the amount

of water, type of soil, type of tomato plant, initial size of plant, size of their containers, etc.

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Charts, Tables, and Graphs

ANALYSIS OF DATA

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Analysis of the Data

Data tables, flow charts and graphs present the information collected during an experiment.

What the data shows, any trend in information is explained in the analysis of data.

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Qualitative Data is data that uses words, describing

certain characteristics. (it is cold outside)

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Quantitative Data –

numerical data, gives

precise amounts

(it is 32o outside)

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Graphs are used to organize data.

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Pie or Circle Graphs

Pie graphs represents

parts or percents of

a whole.

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Line Graph

A line graph uses plotted data points and lines to

show the relationship

between variables.

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Bar Graph

A bar graph compares data using bars of

different heights and

lengths.

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Axis

The independent variable is graphed on the X-axis.

The dependent variable is graphed on the Y-axis.

X-axis

Y-axis

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Data TableA data

table organizes data into rows and columns.

Columns

Rows

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Reading Tables and Graphs

1. When a question includes a table or graph, read it first, before reading

the question.

Don’t just Look at it READ IT.

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While you are reading the graph, pay attention to the following:

2. What is the title, what is being measured or compared? What units

(grams, mLs, minutes, years) are given? Are the numbers or slope

increasing, decreasing?

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After reading the data, now read the question!

The table shows environmental factors and soybean production for three regions. Which of the following probably accounts for the decrease in soybean yield in Region 1?

F High levels of ozone damaged the soybean plants, decreasing the average yield.G Low rainfall amounts failed to meet the plants’ moisture needs and inhibited growth.H Poor mineral levels found in the soil in that region limited the soybean harvest.J Higher-than-normal rainfall increased pest activity, decreasing the average yield.

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What do you have to know?

F

*1st you really only have two choices, decreased rainfall, or O3 level. *Since the rainfall did not decrease consistently (it actually increased in 1999) that would not be a good answer. *Therefore, it must be the O3, which is the chemical formula for ozone. Answer?

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Reading Graphs Always read the

title. Read the x- & y-

axis labels & UNITS.

What is happening?As the pressure

of oxygen increases, the % saturation is

increased.

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Match the type of graph with its use.

Circle Graph

Bar Graph

Line Graph

Used to compare several categories

Shows the relationship between two measured quantities

Shows a single measurement of a number objects or events

Shows how a whole is divided into its parts.

Used to make predictions and show trends

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INFERENCES

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An inference is an explanation based on observations or

trends.For example, if you wake up in the morning and see water on your car and on the ground, you could infer that it rained even though you did not actually see it happen.

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TAK Obj. 01TEKS B.2C

Answer: C

1.

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The graph shows the

increase in a Stentor

population. If this trend

continues, what will be

the approximate size of

the Stentor population

after 4 weeks?

A. 325 per 100 mL

B. 348 per 100 mL

C. 401 per 100 mL

D. 454 per 100 mL

Answer: C

2.

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TAK Obj. 01TEKS B.2D

Answer: C

3.

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TAK Obj. 01TEKS B.2A

Answer: B

4.

A

B

C

D

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TAK Obj. 01TEKS B.2B

Answer: D

5.

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6. Which graph best shows the comparison of the elements to the total composition of the copper ore?

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This is noncontinuous data (not time or temperature or increasing forces) and it is in percentages. D is a pie graph which shows percentage parts of the whole!

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7. An environmental-science company measured the ozone pollutant levels at two different locations in a metropolitan area. Which statement is best supported by these data?

Look for the unsafe levels and where and when they occur.

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Both occurred on 7/15 at a temperature of 38 oC, so . .

A Lower fuel efficiency and northerly winds in the winter increase ozone pollution the most.

B Northwest winds in the spring transport ozone pollution into the metropolitan area.

C High summer temperatures and southerly winds contribute to high levels of ozone.

D Heavy use of automobiles changes ozone levels the most.

This is true, however not supported by the data in the table since both downtown and

northwest areas had increases.

winterspring

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TAK Obj. 01TEKS B.2C

Answer: B

8.

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9. Many doctors recommend 800 µg of folate, 400 µg of vitamin B12, and 50 mg of vitamin B6 per day to improve cardiovascular health. Based on this information and the nutrition label, the cardiovascular health benefit of a 1-ounce serving of this cereal is —

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A doubtful because it provides insufficient folate and vitamin B6 and lacks vitamin B12

B superb because it contains only 22 g of carbohydrates and 75 mg of sodium

C excellent because it provides all needed vitamins and is low in fat and cholesterol

D poor because it raises blood cholesterol levels with its high fat and cholesterol content

Since the question asks about the nutritional value based on Folate and the B vitamins, evaluate the answers based on the same information.

B is not valid since no information is given as to what are good levels.

C is not valid as it does not provide all the vitamins.

D is not a valid answer since it is very low in fat.

ANSWER: A

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Answer: C

10.

A

B

C

D

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Answer: C

11.

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Answer: B

12.

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Answer: B

13.

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Answer: A14.

A

B

C

D

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Answer: 200

15.

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Answer: D

16.

A

B

C

D

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Answer: B17.

A

B

C

D

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Answer: B18.

A

A

B

C

D

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Answer: D

19.

A B

C D

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Answer: C

20.

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TAKS 2009 TEST QUESTIONS

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H

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D

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A

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C

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A

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J

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F

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B

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B

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H

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A

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D

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C

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B