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UNIT 1UNIT 1

Introduction:

Scientific Method & Biology Today

Scientific MethodScientific Method

The Process of Science

• The word science is derived from a Latin verb meaning “to know.”

– Science is a way of knowing.

– Science developed from people’s curiosity about themselves and the world around them.

• Science seeks natural causes for natural phenomena.

– This limits the scope of science to the study of structures and processes that we can observe and measure.

• Verifiable observations and measurements are the data of discovery science.

– In biology, discovery science enables us to describe life at its many levels.

Discovery Science

Hypothesis-Driven Science

• As a formal process of inquiry, the scientific method consists of a series of steps.

– The key element of the scientific method is hypothesis-driven science.

• A hypothesis is a tentative answer to some question.

– It is an explanation on trial.

Hypothesis-Driven Science

• Once a hypothesis is formed, an investigation can test the hypothesis

• the hypothesis is tested by performing an experiment to see whether results are as predicted.

The Scientific Method

A series of steps that are used to solve a problem or better understand an event.

Observation

We can do observations BEFORE conducting an experiment.

This allows us to start thinking about what we are seeing.

1. Asking a Question

Based on observations; one or more research questions are generated

Ex. What is the effect of sunlight on plant growth?

More Observation/Research

Observe the world using your senses (sight, sound, taste, touch, smell) and research your problem using the internet or books or journals.

Inference: involves a judgment

or assumption

2. Forming A Hypothesis

• hypo (less than) thesis (theory)

• Explanation for what you have seen and recorded in your prior obsevervations. Predict a solution to the problem based on your research.

• An educated guess

• a question or statement that can be tested. Ex. If sunlight has an effect on plant growth, then plants will grow larger in the sun because it is needed for photosynthesis.

Forming a Hypothesis Continued…

1. Statement is testable if evidence can be collected that either does or doesn’t support it

2. It can never be proven beyond doubt

3. Often must be refined and revised or discarded

Predicting

• To test hypothesis it is necessary to make predictions that logically follows from the hypothesis

• A statement made in advance that states the results that will be obtained from testing the hypothesis

• Often in the form of an “if-then” statement

3. Experiment

A procedure to test a hypothesis, under controlled conditions – conducting a controlled experiment.

It is clear and detailed so another scientist can replicate your experiment.

List all materials.

Controls & Constants

Control group

The group or sample that is used as a standard for comparison.

Ex. The plant in the dark (compare to plants in different amounts of light).

Constant (controlled variable)

The factors in the experiment that need to stay the same between the experimental group and the control.

Ex. amount of soil, nutrients, water is the SAME for all plants

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3 Kinds of Variables

1. Controlled Variable – a variable that is not changed

• Also called constants

• Allow for a “fair test”

Controls ensure that all variables in the experiment are the same except for the variable being tested.

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3 Kinds of Variables

2. Independent Variable – something that is changed by the scientist

• What is tested (the treatment)

• What is manipulated

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3 Kinds of Variables3. Dependent Variable – something that might be

affected by the change in the independent variable

• What is observed

• What is measured

• The data collected during the investigation (the result of the treatment)

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For Example:

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Students of different ages were given the same jigsaw puzzle to put together. They were timed to see how long it took to finish the puzzle.

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Identify the variables in this investigation.

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What was the independent variable?

Ages of the students

•Different ages were tested by the scientist

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What was the dependent variable?

The time it to put the puzzle together

•The time was observed and measured by the scientist

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What was a controlled variable?

Same puzzle

•All of the participants were tested with the same puzzle.

• It would not have been a fair test if some had an easy 30 piece puzzle and some had a harder 500 piece puzzle.

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Another example:

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An investigation was done with an electromagnetic

system made from a battery and wire wrapped around a nail. Different sizes of nails were used. The number of

paper clips the electromagnet could pick up was measured.

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What are the variables in this investigation?

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Independent variable:

Sizes of nails

•These were changed by the scientist

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Dependent variable:

Number of paper clips picked up

•The number of paper clips observed and counted (measured)

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Controlled variables:

Battery, wire, type of nail

•None of these items were changed

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One more:

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The higher the temperature of water, the faster an egg

will boil.

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Independent variable – temperature of water

Dependent variable – time to cook an egg

Controlled variable – type of egg

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Last one:

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The temperature of water was measured at different depths

of a pond.

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Independent variable – depth of the water

Dependent variable – temperature

Controlled variable – thermometer

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Designing Investigations

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The greater the amount of soap in a soap and water mixture, the bigger a soap bubble can be blown.

Design an investigation to test this hypothesis.

• Identify the variables

• What exactly will be changed? How will it be changed?

• What exactly will be measured? How will it be measured?

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The farther a ball drops, the higher it will bounce.

Design an investigation to test this hypothesis.

• Identify the variables

• What exactly will be changed? How will it be changed?

• What exactly will be measured? How will it be measured?

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4. Collecting Data

Data: The information collected from an experiment.

Data is data, it isn't right or wrong - presented in tables, charts, notes or diagrams.

Two Types

• Quantitative

• Qualitative

• Quantitative Data

– quantity - measured in numbers

• Qualitative Data

– quality - measured in words (descriptions)

Types of Data

AND

•Observation - recognizing and noting some FACT to gather information about the world

•You make observations using your five senses •Observations must be specific and accurate, not relative, so that it means the same to everyone.

•Example: •Incorrect - the burning bag smelled nasty •Correct - the burning bag smelled similar to rotten eggs

•Inference - a possible explanation or guess about an observation

•Example: you leave the movie theater and see the ground is wet so you infer that it rained.

The picture shows the label on a carton of orange juice. Which of these is supported by the information on the label?

a. Orange juice turns all vitamins into vitamin C.

b. Orange juice provides vitamin C to the body.

c. Orange juice removes vitamin C to the body.

d. Orange juice cause the body to need vitamin C

The table in dictates the amount of time that four different brands of batteries worked in a flashlight. Which of the following statements is supported by this information?

A. Brand “A” caused the light to shine farther than the other brands.

B. Brand “M” lasts longer than the other brands.

C. Brand “ N” gave off a stronger light than the other brands

D. Brand “O” is more expensive than the others.

An advertisement for a breakfast food states that the product is the “healthiest choice”. Which of these could show that this is a valid claim?

A. The bar code

B. The nutrition information

C. The number of grams

D. The pictures on the box

The picture shows a bottle of “Fun Sun Cream”. Which of these statements indicates how well this product helps prevent skin damage?

A. Great for all outdoor activities

B. Contains the finest ingredients

C. Sun protection factor (SPF) 30

D. Money-back guarantee

Q R S T

Which of these foods would be the best choice for someone on a low-fat, low sodium diet?

A. Q

B. R

C. S

D. T

5. Analyzing Data

Make interpretations of data by graphing data, correlating data with facts, using mathematical analysis etc.

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6. Conclusions & Reporting of Data

Report data - put your numbers into words. Answer: What was found out and how do you know it to be true? How did it relate to your hypothesis? Did it support or fail to support?

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Communication

Share the results of their studies with other scientists

Publish findings in journals or at scientific meetings

Sharing of information is essential to scientific process

Subject to examination and verification by other scientists

Allows scientists to build on the work of others

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Analyze process and repeat

All valid data is reproducible

Forming a Theory

A theory may be formed after many related hypotheses have been tested and supported with experimental evidence

A broad and comprehensive statement of what is thought to be true

Supported by considerable evidence

Ties together related hypotheses

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Theory

Explanation supported by a large amount of evidence obtained from many different investigations over a long period of time.

Common Misconception: Theory defined as a guess is not the scientific definition.

Example: Theory of Evolution

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LawGenerally less complex than theories

A theory explains a law.

Examples: Law of Gravity, Law of Conservation of Energy, Law of Conservation of Matter

Law: A rule of nature that sums up related observations and experimental results to describe a pattern in nature (states WHAT happens).

Law of Gravity, Laws of Motion

Theory: A logical explanation of WHY or HOW things work the way they do, based on many observations supported by experimental results.

Atomic Theory, Big Bang Theory

Theories can serve as explanations of laws!

Both laws and theories can be changed or discarded if new observations show them to be incorrect!

Law vs. Theory

Measurements

We will be using SI (International System of Measurement ) units or metric system when possible --- get use to it --- the WHOLE world uses it except us (USA)

Examples: length in meters, volume in liters, temperature in Celsius, mass in grams and time in seconds.

Did You Know?

• We are living in a golden age of biology.

– Modern biology is as important as it is inspiring, with exciting breakthroughs changing our very culture.

Biology and Society: Living in a Golden Age of Biology

• Biology is the scientific study of life.

The Scope of Life

– Life is structured on a size scale ranging from the molecular to the global.

– Biology’s scope stretches across the enormous diversity of life on Earth.

Biology Bio (life) ology (study of)

• The phenomenon we call life defies a simple, one-sentence definition

• There are several characteristics of living things.

The Unity of Life

Seahorse Camouflage

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Characteristics of Living Things

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1. Cells

All living things are composed of cells

Cells and Their DNA

• The cell is the lowest level of structure that can perform all activities required for life.

– All organisms are composed of cells.

Generalized Cell

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2. Organization / Order

Living things are organized

All structures have a function

• There are many MANY ways to look at organization

– Molecular organization

– Cellular organization

– Organ/tissue organization

– Gender, size, systems, etc

Example:

In multicellular organisms cells and groups of cells (tissues) are organized by their function

• Cells tissues

• Tissues organs

• Organs systems

• Systems organism

Organization

Cellular Organization Systemic Organization

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3. Energy

All living things use energy in a process called metabolism.

• The sum of all chemical processes that occur in an organism.

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EnergyThe ability to do work. Work is anything that causes

motion. Work is required to be a living thing. Every living thing uses energy from some of the materials in food as fuel for the functions needed to keep it alive.

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Autotrophs

• Organisms that make their own food are called autotrophs

– Phototrophs – use solar energy (photosynthesis) to get energy

• Convert H2O and CO2

into sugar and O2

– Chemotrophs – use different chemical processes to get energy

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Energy continuedAlmost all energy comes from the sun (directly or

indirectly)

• Photosynthesis is the process by which some organisms capture the energy from the sun (solar) and transform it into energy (chemical) that can be used by living things

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Heterotrophs

Organisms that must take in food to meet their energy needs are called heterotrophsConsume autotrophs (herbivores), other heterotrophs (carnivores) or both (omnivores) for their energy needs

Complex chemicals are broken down and reassembled into chemicals and structures needed by organisms

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4. Adaptation

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Adaptation

Any structure, behavior, or internal process that enables an organism to respond to stimuli and better survive in an environment.

Ability to adapt to their environment through the process of evolution

Favorable characteristics are selected for and passed on to offspring

Evolution

• The gradual accumulation of adaptations over time.

• Change over time.

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5. Reproduction

All species have the ability to reproduce

• Not essential to survival of individual but is essential for continuation of a species

Species

A group of organisms that can interbreed and produce fertile offspring

Donkey Horse

Mule

Reproduction

All living things have the ability to reproduce and pass on their genetic material (DNA) to their offspring.

Living organisms can reproduce asexually or sexually

Sexual reproduction involves an egg and sperm.

Asexual reproduction takes the form of cloning, budding, root propagation, or self fertilization.

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•Growth is increasing in size over time.

•Development is changing toward final adult form.

5. Growth & Development

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6. Respond to the Environment

Respond to stimuli in the external environment.

Environment An organisms surroundings, which includes the air,

water, weather, temperature, and any other organisms in the area.

Stimulus

A condition in the environment that causes an organism to adjust.

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ResponseThe reaction to a stimulus.

Homeostasis – An example of how your body responses

homeo (same) stasis (steady state)

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Stability and homeostasis

Regulation of internal conditions in order to adjust to external environment. Maintain very stable internal conditions

Example: temperature 37° hot-perspirecools cold-shiverwarms Other examples include: water content, chemical content, etc.