Biology & The Scientific Method - Weebly

Biology & The Scientific Method - Weebly

BIOLOGY & THE SCIENTIFIC METHOD Sciencean organized way of gathering and analyzing evidence about the natural world.

What is Biology? Biologya science that employs scientific methodology to study living things. It is the science, and study, of life. Bio- means life, and ology means the study of

The Scientific Method Scientific Method- Precise method used by scientists

that separates science from other ways of studying & learning. Observing and Asking Questions Scientific investigations usually begin with an observation, the act of noticing and

describing events or processes in a careful, orderly way. For example, researchers observed that marsh grass grows taller in some places than others. This observation led to a question: Why do marsh grasses grow to different heights in different places?

Inferring and Forming a Hypothesis After posing questions, scientists use further observations to make inferences, or logical interpretations based on what is already known. Observation____________________ Inference__________________

Observation or Inference ? Students are working with a newly discovered organism. Is their statement an observation or an inference? ___ 1. The organism frowned to show it did not like strangers. ___ 2. The organism is green with pink spots.

___ 3. The organism lives near other organisms. ___ 4. The organism moved away from us because it was scared. ___ 5. The organism made gurgling noises. ___ 6. The organism had four spines on its back. ___ 7. The organism has one blue eye and two

green eyes. ___ 8. The organism moves really slow so he must be old. Steps to the Scientific Method 1. State the problem.

2. Research / Gather Information 3. Form a Hypothesis Hypothesis- an

educated guess; often based on inferences Make it short & definitive. an if then statement Inferring and Forming a Hypothesis Researchers inferred that something limits grass growth in some places. Based on their

knowledge of salt marshes, they hypothesized that marsh grass growth is limited by available nitrogen. 4. Test the Hypothesis Develop a controlled experiment -an

experiment that contains only one experimental variable. Controlling Variables It is important to control variables because if several variables are changed in the experiment, researchers cant easily tell which variable is responsible for any

results they observe. The variable that is deliberately changed is called the independent variable (also called the manipulated variable). The variable that is observed and that changes in response to the independent variable is called the dependent variable (also called the responding variable).

Controlled VariablesAll other variables in the experiment that are kept the same Control and Experimental Groups Typically, an experiment is divided into control and experimental groups. A control group is exposed to the same

conditions as the experimental group except for one independent variable. . Designing Controlled Experiments The researchers selected similar plots of marsh grass. All plots had similar plant density, soil type, input of freshwater,

and height above average tide level. The plots were divided into control and experimental groups. The researchers added nitrogen fertilizer (the independent variable) to the experimental plots. They then observed the growth of marsh grass (the dependent variable) in both experimental and control plots. Collecting and Analyzing Data

Scientists record experimental observations, gathering information called data. There are two main types of data: quantitative data and qualitative data. Quantitative Datadeals with numbers data which can be measured

Ex>length, height, area, volume, weight, speed, time, temperature, humidity, cost sound Collecting and Analyzing Data In the marsh grass experiment, it could include the number of plants per plot, plant sizes, and

growth rates. Qualitative Datadeals with a description data that can be OBSERVED but not measured Ex>colors, textures, smells, tastes,

Collecting and Analyzing Data In the marsh grass experiment, it might include notes about foreign objects in the plots, or whether the grass was growing upright or sideways. There are 30 students in the

class. Quantitative The freshman class has positive school spirit. Qualitative

This coffee has a serving temperature of 150oF. Quantitative Bobbys coffee is in an orange mug.

Qualitative 5. Analyze Data & Draw Conclusions Analyze experimental results and record observations

Organize data into graphs & tables Is your hypothesis supported? If a hypothesis is proven incorrect,

change the hypothesis, not the data Drawing conclusions Experiments must be reproducible and produce consistent results. A hypothesis can

change based on results of an experiment. In the experiment, analysis showed that marsh grasses grew taller than controls by adding nitrogen. Drawing Conclusions The original hypothesis is

reevaluated and revised; new predictions are made, and new experiments are designed. Hypotheses may have to be revised and experiments redone several times before a final hypothesis is supported

and conclusions can be drawn. Example 1 State the Problem: Is Raid the best insecticide on the market?

Research: Find information on the topic in books, the Internet, calling a customer service rep. for the product

Hypothesis: If Raid is the best insecticide on the market, then it will kill insects 30% faster than three other insecticides. Test the hypothesis in a

controlled experiment Spray 4 separate containers with equal amounts of 4 different insecticides (one of which is Raid). Cover each one with the same type and size glass. Add equal amounts of the same type of insects (10) to each glass. Place them side-byside and time the results.

Data Container # #living 1 min

#living 2 min #living 3 min #living 4 min

1 (Raid) 10 0 0

0 2 10 10

8 4 3 10

10 6 3 4

10 10 4 2

Conclusion Raid is the best insecticide on the market. It killed insects 30% faster than three other insecticides.

Scientific Theories In science, the word theory applies to a well-tested explanation that unifies a broad range of observations and hypotheses and that enables scientists to make accurate predictions about new situations.

Theoryexplanation of events or things based on knowledge gained from many observations and investigations The WHY Scientific Theories

Evidence may support several related hypotheses in a way that inspires researchers to propose a scientific theory that ties those hypotheses together. A useful theory that has been thoroughly

tested and supported by many lines of evidence may become the dominant view among the majority of scientists. Scientific Theories No theory is considered absolute truth. Science is always changing; as new evidence

is uncovered, a theory may be revised or replaced by a more useful explanation. Lawa statement about what happens in nature and seems to be true all of the time The What

GRAPHING Grapha visual display of information used by scientists to display data collected during a controlled experiment

Parts of a Graph 1. Title 2. Independent variable 3. Dependent variable 4. Scales for each variable

Titlea concise statement usually placed above the graph that identifies what the graph is about Independent Variablethe variable that is controlled

by the experimenter often includes time (dates, minutes, hours), depth (feet, meters), temperaturewhat you change placed on the X-axis Dependent Variablevariable that is directly

affected by the independent variable the result of what happens because of the introduction of the independent variable placed on the Y-axis Which battery brand is

most reliable? Scales for each Variable range must include all data points must take up an appropriate amount of space often starts at zero and

climbs based on consistent intervals Legenda short descriptive narrative explaining the graphs data should be short & concise and usually

placed under the graph Temperature o ( C) 10 15 18

20 23 25 Breathing Rate (per minute) 15

25 30 38 60 57 Breathing Rate of Freshwater Sunfish

70 60 Breathing Rate (per minute) 50 40

30 Is this scaled properly? 20 10 0 10

15 o 20 18 Temperature C

23 25 Time After Eating (hours) 0.5

Glucose (ml) / L of blood Person A 170 Glucose

(ml) / L blood Person B 180 1 155

195 1.5 140 230

2 135 245 2.5

140 235 3 135

225 4 130 200

400 Glucose Levels of Two People Glucose (ml) / L of Blood 350

300 250 200 Series 3 Person A 150

100 Where is 3.5? 50 0 0.5

1 1.5 2 2.5

Time After Eating (hours) 3 4 A graph takes info

displayed in a table and makes it easier to observe trends Characteristics of Life All life on earth shares several unifying characteristics.

1. Living things are made of cells cellssmall, self-contained units that are the building blocks of life

Unicellular and Multicellular organisms Unicellular- a single cell carries out all of lifes functions Ex> bacteria Multicellular- trillions of cells can be

working together to carry out life functions, having specialized functions within the organism 2. Living things grow & develop organisms absorb raw materials and

process them into new tissues and structures Single celled organisms grow larger, while multicellular organisms grow by their cells dividing over and over.

3. Living things obtain & use energy Characteristics of Living Things For example, leaves obtain energy from the

sun and gases from the air. These materials then take part in various chemical reactions within the leaves. Animals ingest organisms like plants or other animals who have already consumed plants themselves. MetabolismA set of chemical reactions

that occur in living organisms in order to maintain life. 4. Living things respond to their environment stimulusanything

detected in an organisms environment that causes it to react Ex. light, odor, sound, heat Some responses are behavioral, such as a rabbit running from a predator or a plant

moving its leaves to face incoming sunlight. Other examples can include a plant producing a poisonous chemical to ward off insects from eating its leaves. Plants and animals can detect changes such as light, temperature, and even gravity.

Organisms and their cells function best at certain temperatures, pH levels, solute concentrations, etc. They must maintain these levels from becoming too high or low. HomeostasisThe bodys ability to

regulate its internal physiology to maintain stability in response to fluctuations in the outside environment In low light environments, your pupils dilate and allow more light to pass into

the eye. This is a response to a stimulus- low light level. This also is an example of maintaining homeostasis, using energy to maintain constant light levels in the eye. 5. Living things have the ability

to reproduce ReproductionBiological process by which new individual organisms are produced. A fundamental feature of all known lifeeach

individual exists as a result of reproduction Two main types of reproduction 1.sexual 2.asexual

Characteristics of Living Things Most plants and animals engage in sexual reproduction, in which cells from two parents unite to form the first cell of a new organism.

There are examples of unicellular organisms and multicellular organisms that can reproduce sexually or asexually. Organism-

An individual living thing Ex. tree, frog, human 6. Living things evolve

Characteristics of Living Things Over generations, groups of organisms evolve, or change over time. Evolutionary change links all forms of life to a common origin more than 3.5 billion years ago. Characteristics of Living Things Evidence of this shared history is found in all

aspects of living and fossil organisms, from physical features to structures of proteins to sequences of information in DNA. For example, signs of one of the first land plants, Cooksonia, are preserved in rock over 400 million years old. MICROSCOPES

Anton Van Leeuwenhoek found that by placing glass lenses (lenses refract light) at certain distances from each other, he could enlarge objects in his field of vision Invented the 1st microscope (light microscope)

Leeuwenhoek developed what is called a simple microscope since it had only one lens. We mostly use compound microscopes since they have more than one lens. Important Microscopy

Terms Magnification the comparison of the real size of a specimen with that of the one viewed under the microscope

Resolving Power a.k.a. resolution refers to the clarity of the specimen viewed under the scope Image of pollen grain with good

resolution (left) and poor resolution (right) Parts of a Compound Light Microscope Coarse focus adjustment knob

Focuses the image under low power Usually the bigger knob Makes larger adjustments Fine focus adjustment knob Sharpens the image under all powers Usually the smaller knob

Fine Adjustment Knob Arm Supports the body tube and is used to carry the microscope

Arm Body Tube Connects the eyepiece to the nosepiece Usually moves during focusing Body Tube

Eyepiece The lens you look through Usually at 10X magnification Eyepiece Nosepiece a.k.a. revolving nosepiece holds all the objectives and it

revolves Nosepiece Base Supports the microscope and used for carrying the microscope

Base Stage Used to support the slide Stage Stage Clips Used to hold the slide in place

Stage Clips Diaphragm Used to regulate the amount of light Diaphragm

Light Source Provides light Light Source Low Power Objective Has the lowest magnification and is the shortest objective

Low power objective Medium Power Objective increases the magnification Medium Power

Objective High Power Objective Provides the most magnification and is the longest objective. High Power Objective

Calculating magnification 1. Determine the magnification of the eyepiece (ocular lens) and each objective. 2. Multiply the magnification of the eyepiece with the magnification of the objective you are using.

Example Calculate the magnification of a microscope with an eyepiece magnification of 10 and objective magnification is 30. Answer: 10 X 30 = 300 Objectives of Microscope Lab

To learn the parts of the microscope. To find specimens using low and high power. To make a wet mount. To view your own human cheek cells under the

Microscope Care Always carry with 2 hands Only use lens paper for cleaning Do not force knobs Keep objects clear of desk and cords

Microscope Parts Eyepiece Body Tube Revolving Nosepiece Objective Lens Stage Clips Diaphragm

Arm Stage Coarse Focus Fine Focus Light Base

Using the Microscope Place the Slide on the Microscope Use Stage Clips Click Nosepiece to the lowest (shortest) setting Look into the Eyepiece

Use the Coarse Focus Using High Power Follow steps to first focus using low power Click the nosepiece to the longest objective Do NOT use the Coarse Focusing

Knob Instead use the Fine Focus Knob to bring theWhat slide into view can you find on your slide?

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