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Chapter 1: The Study of Life

Section 1.3: Scientific Thinking and Processes

Section 1.4: Biologists’ Tools and Technology

Section 1.5 Biology and Your Future

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1.3 Scientific method A series of steps used to solve a problem

1. Make an observation- Use your senses to record data and study the world.- Observations can recorded as data. 1. Qualitative data - include descriptions such

as sights, sounds, touch, taste and smells.

2. Quantitative data – can be measured or counted such as mass, volume, temperature.

2. Form a hypothesis- Based on your observations and data research, what do you think will happen? Or what could be a possible explanation?

- A hypothesis is a proposed answer for a scientific question that can be tested.- Has to be testable!- When data does bot support a hypothesis, it is

rejected.

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Scientific method A series of steps used to solve a problem

3. Conduct a controlled experiment - Testing the hypothesis using a step-by-step procedure.

- A controlled experiments tests 1 variable at a time. 1. An independent variable - a condition that is

changed or manipulated by a scientist.- What you are testing.

2. A dependent variable – what you are observing and measuring during the experiment.

- Everything in a controlled experiment remains constant (the same) except for one thing that you

change.

Scientific method

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3. Controlled experiment continued - A controlled experiment needs to have 2 groups.

1. The experimental group – receives the independent variable.

2. The control group – is used for comparison to the experimental group.

Scientific method

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4. Analyze the Data – Interpret the recorded results of the experiment in order to make a conclusion.

5. Draw a conclusion – Evaluate the results. - A conclusion should address the following:

• Was the hypothesis correct?• How does the data support your conclusion?• Were there errors that might have changed the

results?• How might those errors be avoided next time?

Scientific method

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SCIENTIFIC METHOD CONTINUED- Experiments should be repeated many times to

check the results for consistency.

- If the results are not the same then a new hypothesis needs to be made.

- A hypothesis can become a theory if it is tested over and over again and is supported with a wide range of evidence. – A theory can be used to predict the outcome of other

events.– Theories are not proven to be true.– Theories can change based on new evidence.– Are supported by a wide range of evidence. 7

SCIENTIFIC METHOD CONTINUED

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IV. Biologists’ Tools & Technology

• Technology continually changes the way biologists work.

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IV. Magnifying Tools of a biologist.

A. Microscope – used to enlarge objects that are extremely small, used to see fine detail.

- 4 Types of Microscopes

There are special tools a scientist might use to make

things look bigger

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Types of Microscopes1. Light Microscope (LM) (also known as a compound

microscope)- The object has to be small and thin in order for light

to pass through the object.- Have many lenses that magnify the object.- Can magnify an object up to 400 times its original

size.- Produce a 2-dimensional image.- Show the actual color of the specimen.

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Types of Microscopes Continued2. Stereomicroscope (also known as a dissecting

microscope) - Used to look at objects that are too large or thick and

therefore light cannot pass through - Produces a 3-D image

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Types of Microscopes Continued3. Scanning Electron Microscope (SEM)– - Uses high energy electrons in order to magnify objects

that are too small to be seen by the naked eye.- A computer produces a 3-D image and adds color.- Can magnify objects more than 500,000 times its

original size.

An image of a house fly compound eye surface by using Scanning Electron Microscope

These pollen grains taken on an SEM show the characteristic depth of field of SEM micrographs.

SEM opened sample chamber

4. Transmission Electron Microscope (TEM)–-Transmits electrons through a thin slice of specimen.-Shows a 2-D image.-Colorized by computer.

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Types of Microscopes Continued

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• LM

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• SEM

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• TEM

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More Tools Scientist Use! B. Slide – glass platform used to view specimens through the microscope.

C. Slide Cover/Coverslip – place over specimen on slide to protect specimen.

D. Safety goggles – protect eyes.

E. Triple Beam Balance – measure the mass of small objects.

F. Electronic or digital Scale – measures the mass of various objects.

G. Beaker – holds larger volumes of liquid. Estimates volume, not 100% accurate.

H. Graduated cylinder - a tall narrow container used to measure exact amounts of volume. Read by the meniscus.

I. Erlenmeyer Flask – holds liquids – often used when swirling is necessary or to restrict the surface area being exposed.

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More Tools Scientist Use!

J. Thermometer – measures temperature in Celcius or Fahrenheit.

K. Metric Ruler – measure length in metric length.

L. Eye Dropper – for imprecise delivery of small volumes of liquid, not used for an accurate measurement.

M. Pipette – for precise delivery of liquids, accurately measures a liquid.

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More Tools Scientist Use!