Lab 1

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Lab 1
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• Biology Exploring Life

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Antibiotics

• Too Much of a Good Thing?

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Antibiotics

• Your doctor prescribes an antibiotic and
  specifically cautions you to take every pill.
• Why?

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Antibiotics

• Checkpoint

• What is an antibiotic?
• a. It is a toxin used by bacteria to kill molds.
• b. It is a drug that can kill infectious
  bacteria.
• c. It is a chemical produced by the body to
  defend itself against viruses.
• d. Its an area with
• conditions that
• dont support life.
• e. None of the
• above are correct.

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Antibiotics

• Checkpoint

• Human white blood cells ________.
• a. carry oxygen and carbon dioxide to the lungs
• b. store antibiotics for release at sites of
  infection
• c. serve as one of the bodys natural lines of
  defense against microbial invaders
• d. gather and eliminate antibiotics from the site
  of an infection
• e. All of these are correct.

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Antibiotics

• Checkpoint

• About half of the antibiotics produced today
  __________.
• a. end up in animal feed
• b. are used by field hospitals in war zones
• c. are shipped to third-world countries
• d. become useless due to developing resistance by
  bacterial populations
• e. are stored for later use

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Antibiotics

• Checkpoint

• How do bacteria populations become drug
  resistant?
• a. Antibiotics remove drug-susceptible
  individuals but leave those that are
  drug-resistant.
• b. Natural selection drives bacterial populations
  to change.
• c. Some individuals are genetically resistant to
  antibiotics.
• d. All of these are correct.

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Antibiotics

• Checkpoint

• Which of these is not an effective strategy to
  prevent antibiotic resistance?
• a. Dont stockpile antibiotics.
• b. Dont demand antibiotics from your physician.
• c. Use antibiotics only as long as symptoms
  remain.
• d. Use antibiotics as prescribed.
• e. Dont share antibiotics with others.

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Antibiotics

• Biology and Society

The development of antibiotic resistance by
bacteria illustrates how natural selection
affects our lives. Can you name another way our
society experiences the effects of natural
selection?
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Antibiotics
Biology and Society

• Discussion Question
• The development of antibiotic resistance by
  bacteria illustrates how natural selection
  affects our lives. Can you name another way our
  society experiences the effects of natural
  selection?
• Follow-Up Questions
• Is it likely that insect or plant pests (weeds)
  might develop resistance to pesticides and
  herbicides?
• Some plants, like BT corn and BT cotton, are
  being engineered to include a pesticide gene.
  What do you predict to be the long-term success
  of such a strategy? What strategies should a
  farmer employ to prevent pests from becoming
  resistant?
• Antibiotic resistance in bacteria is not the only
  case in which humans are causing pressures that
  contribute to the natural selection of a
  population. Other examples include insect
  resistance to BT corn, BT cotton, and other
  natural and genetically altered crops
  (http//www.nature.com/nsu/021202/021202-2.html).
  A great deal of research is being conducted to
  develop strategies to prevent pest populations
  from developing pesticide resistance
  (http//www.biotech-info.net/ECB.pdf).

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Antibiotics

• Biology and Society

Many antibioticslike penicillinare no longer
effective, but it is costly to develop
replacements. Do we have an obligation to
societies that cannot afford to develop these new
and expensive antibiotics?
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Antibiotics

• Biology and Society

About 50 of the antibiotics produced today are
used in the livestock industry. What impact does
this have on the treatment of human diseases?
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Antibiotics

• Internet Research

• Antibacterial Soap Doesnt Prevent Viral
  Infection
• (http//kidshealth.org/research/antibacterial_prod
  ucts.html) This article outlines our use and
  misunderstanding of antibacterial soaps. Are
  there concerns that bacteria will develop
  resistance to antibacterial soaps?
• Drug Companies Snub Antibiotics
• (http//www.nature.com/nsu/030915/030915-6.html)
  The article speculates that drug companies are
  spending less money and less effort to develop
  new antibiotics. What evidence does the author
  cite? What are the consequences to global health
  if this is the case?
• Is Your Meat Safe?
• (http//www.pbs.org/wgbh/pages/frontline/shows/mea
  t/safe/) This site outlines the debate over the
  use of antibiotics in the livestock industry.
  Familiarize yourself with the issues, then share
  your thoughts (http//www.pbs.org/wgbh/pages/front
  line/shows/meat/talk/). Was the coverage fair and
  unbiased?

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Antibiotics

• Summary

• We didnt have antibiotics before the 1940s.
• Alexander Fleming helped to develop the first
  antibiotic from a mold.
• Antibiotics work to kill infecting bacteria.
• Natural variations exist within bacterial
  populations that make some bacteria resistant to
  antibiotics.
• Abuse of antibiotics promotes the development of
  antibiotic-resistant bacteria.

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Antibiotics

• Preventing the development of antibiotic-resistant
  bacteria is in the hands of every individual.
  What actions will you take?

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Five Steps of the scientific method

• Observation come from others or results of
  earlier tests
• Questions are asked about unclear aspects of the
  observations How? Why? When?
• Hypotheses are tentative explanation of a
  phenomenon phrased in such a way as to be
  testable.
• Predictions are logical, testable outcomes of the
  hypotheses developed by the use of deductive
  reasoning. Predictions take the form of if
  (statement of hypotheses) is true, then
  (predictions).
• Tests of prediction are performed to determine if
  the predictions are supported (fail to falsify)
  or falsified.

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Concept Check
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• Not all science discoveries strictly follow the
  scientific method. Which of the following
  would best be described as discovery science?
• Sequencing the human genome.
• Describing a new bird species from the
  Philippines.
• A project to find preserved specimens of the
  probably extinct Rocky Mountain locust frozen in
  glaciers .
• All of the above.

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Answer
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• Not all science discoveries strictly follow the
  scientific method. Which of the following
  would best be described as discovery science?
• All of the above.

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• A Case Study of Hypothesis-Based Science
• In experiments designed to test hypotheses
• The use of control groups and experimental groups
  helps to control variables

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Interpreting Data
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• These two snakes look remarkably similar to each
  other. The coral snake (right) is very poisonous
  to vertebrates. Hypotheses
• H1 The coral snakes bright color pattern
  serves to warn off potential predators.
• H2 The the king snake suffers less predation
  because it mimics or looks like the coral snake.
  
• H3 The protection that king snakes receive by
  mimicking coral snake will depend on the presence
  of coral snakes.

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Interpreting Data
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• A team of scientists designed an investigation
  that used artificial snakes to test the previous
  hypotheses. Which of the previous hypotheses are
  supported by the results displayed at the right?
• H1 The coral snakes bright color pattern
  serves to warn off potential predators.
• H2 The the king snake suffers less predation
  because it mimics or looks like the coral snake.
• H3 The protection that king snakes receive by
  mimicking coral snake will depend on the presence
  of coral snakes.
• Both A and B

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Answer
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• A team of scientists designed an investigation
  that used artificial snakes to test the previous
  hypotheses. Which of the previous hypotheses are
  supported by the results displayed at the right?
• Both A and B

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Interpreting Data
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• Biologists placed artificial snake mimics in two
  different localities to test the hypothesis that
  looking like a poisonous snake only works where
  the poisonous snake is found
• Outside of the coral snake rangeonly king
  snakes present.
• Inside the coral snake rangeboth coral and
  king snakes are present.

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Interpreting Data
0

• The data graphed at the right __________ the
  hypothesis that the effectiveness of mimic
  coloration depends upon the presence of the
  poisonous model is
• supports
• does not support
• is irrelevant to

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Answer
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• The data graphed at the right __________ the
  hypothesis that the effectiveness of mimic
  coloration depends upon the presence of the
  poisonous model is
• supports

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Interpreting Data
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• Based on this data which of the following is a
  logical hypothesis or prediction?
• King snakes outside of the range of coral snakes
  will more closely resemble coral snakes than
  populations of king snake living within the range
  of coral .
• King snakes outside of the range of coral snakes
  will not resemble coral snakes as closely as
  populations of king snakes that live within the
  range coral snakes.
• Neither prediction is valid.

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Answer
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• Based on this data which of the following is a
  logical hypothesis or prediction?
• King snakes outside of the range of coral snakes
  will not resemble coral snakes as closely as
  populations of king snakes that live within the
  range coral snakes.

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Controls

• This case study provides an example of a
  controlled experiment, one that is designed to
  compare an experimental group (the artificial
  king snakes, in this case study) with a control
  group (the artificial brown snakes).
• Ideally, the experimental and control groups
  differ only in the one factor the experiment is
  designed to testin our example, the effect of
  the snakes coloration on the behavior of
  predators.

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Controls

• Without the control group, the researchers would
  not have been able to rule out the number of
  predators in the different test areas as the
  cause of the different number of attacks on the
  artificial king snakes.
• The clever experimental design left coloration as
  the only factor that could account for the low
  predation rate on the artificial king snakes
  placed within the range of coral snakes.

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Hypothesis

• Theory needing investigation a tentative
  explanation for a phenomenon, used as a basis for
  further investigation
• The hypothesis of the big bang is one way to
  explain the beginning of the universe.

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Hypothesis - defined

• A conjecture advanced for heuristic purposes,
  cast in a form that is amenable to confirmation
  or refutation by conducting of definable
  experiments and the critical assembly of empiric
  data not to be confused with assumption,
  postulation, or unfocused speculation.
• Heuristic LOGIC procedure for getting solution
  a helpful procedure for arriving at a solution
  but not necessarily a proof

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Deduction

• Conclusion drawn a conclusion drawn from
  available information.
• Drawing a conclusion the process of drawing a
  conclusion from available information.
• LOGIC logical conclusion a conclusion reached by
  applying the rules of logic to a premise.
• LOGIC reasoning the forming of conclusions by
  applying the rules of logic to a premise

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0

• A Case Study from Ever yday Life
• Deductive reasoning is used in testing hypotheses
  as follows
• If a hypothesis is correct, and we test it, then
  we can expect a par ticular outcome

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Two important qualities of the hypotheses-based
science

• A hypothesis must be testable.
• A hypothesis must be falsifiable.
• A hypothesis becomes credible when repeated
  attempts to disprove it fail.

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Introduction to Lab 1

• scientific inquiry is a particular way of
  answering questions
• questions that can be answered by science must
  meet specific guidelines and scientific
  investigations must be carried out using certain
  rules
• an investigator cannot show that his or her
  experiment was done according to the guidelines,
  then the results of that experiment will not be
  recognized as valid by other scientists

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Introduction to Lab 1

• The purpose of such guidelines can be understood
  by comparing them to sports records. For example,
  a new record set in a track and field event only
  counts if the meet was approved by the governing
  body that sets the guidelines. The site and
  equipment used are scrutinized to be sure that
  they are within the regulations and the athlete
  is tested for use of illicit substances. Only
  when these required conditions are met is the
  record certified as valid.

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Introduction to Lab 1

• In this laboratory you will learn about the
  basic elements of scientific inquiry and how to
  apply this process to solving problems.

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Exercise 1.3 The Elements of an Experiment

• Objectives
• Define and give examples of dependent,
  independent, and standardized variables.
• Identify the variables in an experiment.
• Explain what control treatments are and why they
  are used.
• Explain what replication is and why it is
  important.

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Exercise 1.3 The Elements of an Experiment

• Variables are things that may be expected to
  change during the course of the experiment.
• The investigator deliberately changes the
  independent variable
• He measures the dependent variable to learn the
  effect of changing the independent variable.
• To eliminate the effect of anything else that
  might influence the dependent variable, the
  investigator tries to keep standardized variables
  constant.

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Dependent Variables

• The dependent variable is what the investigator
  measures (or counts or records). It is what the
  investigator thinks will vary during the
  experiment. For example, she may want to study
  peanut growth. One possible dependent variable is
  the height of the peanut plants. Name some other
  aspects of peanut growth that can be measured.
• Number of peanuts, weight of the plants, leaf
  area, time to maturation.
• All of these aspects of peanut growth can be
  measured and can be used as dependent variables
  in an experiment. There are different dependent
  variables possible for any experiment. The
  investigator can choose the one she thinks is
  most important, or she can choose to measure more
  than one dependent variable.

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Independent Variables

• The independent variable is what the investigator
  deliberately varies during the experiment. It is
  chosen because the investigator thinks it will
  affect the dependent variable. Name some factors
  that might affect the number of peanuts produced
  by peanut plants.
• Amount of fertilizer, type of fertilizer,
  temperature, amount of water, day length, genetic
  type of the peanuts.

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Standardized Variables

• A third type of variable is the standardized
  variable. Standardized variables are factors that
  are kept equal in all treatments, so that any
  changes in the dependent variable can be
  attributed to the changes the investigator made
  in the independent variable.

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Standardized Variables

• Since the investigator's purpose is to study the
  effect of one particular independent variable,
  she must try to eliminate the possibility that
  other variables are influencing the outcome.
• This is accomplished by keeping the other
  variables at constant levels, in other words, by
  standardizing these variables.

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Standardized Variables

• For example, if the scientist has chosen the
  amount of fertilizer as the independent variable,
  she wants to be sure that there are no
  differences in the type of fertilizer used. She
  would use the same formulation and same brand of
  fertilizer throughout the experiment. What other
  variables would have to be standardized in this
  experiment?
• Amount of water, temperature, day length, genetic
  type of peanuts.

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Predictions

• A hypothesis is a formal, testable statement
• The investigator devises an experiment or
  collects data that could prove the hypothesis
  false
• He should also think through the possible
  outcomes of the experiment and make predictions
  about the effect of the independent variable on
  the dependent variable in each situation.
• It is useful to think of a prediction as an
  if/then statement If the hypothesis is
  supported, then the results will be ...

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Levels of Treatment

• Once the investigator has decided what the
  independent variable for an experiment should be,
  he must also determine how to change or vary the
  independent variable.
• The values set for the independent variable are
  called the levels of treatment.

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Control Treatments

• It is also necessary to include control
  treatments in an experiment.
• A control treatment is a treatment in which the
  independent variable is either eliminated or is
  set at a standard value.
• The results of the control treatment are compared
  to the results of the experimental treatments

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Control Treatments

• An investigator studies the amount of alcohol
  produced by yeast whenit is incubated with
  different types of sugars. Control treatment
• A treatment with no sugar.
• 2. The effect of light intensity on
  photosynthesis is measured by collecting oxygen
  produced by a plant. Control treatment
• Put a plant in the dark.
• 3. The effect of NutraSweet sweetener on tumor
  development in laboratory rats is investigated.
  Control treatment
• One group of rats receives no NutraSweet
  sweetener.

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• Subjects are given squares of paper to taste that
  have been soaked in a bitter-tasting chemical.
  The investigator records whether each person can
  taste the chemical. Control treatment
• Use some papers that do not contain the chemical.
• 5. A solution is made up to simulate stomach acid
  at pH 2. Maalox antacid is added to the solution
  in small amounts, and the pH is measured after
  each addition. Control treatment
• Add water instead of Maalox antacid.

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Replication

• Replicating the experiment means that the
  scientist repeats the experiment numerous times
  using exactly the same conditions to see if the
  results are consistent.
• A concept related to replication is sample size.
• It is risky to draw conclusions based upon too
  few samples.

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Methods

• investigator must find a method to measure the
  dependent variable otherwise, there is no
  experiment. investigator must find a method to
  measure the dependent variable otherwise, there
  is no experiment.

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