MID YEAR BIOLOGY REVIEW

1. MID YEAR BIOLOGY REVIEW Excerpts from powerpoints used in class (with one exception) during the first semester. Blank slides separate the different topics.

2. Scientific Method Scientific Method – way in which scientists gather information and answer questions. The goal of science is to investigate and understand the natural world, explain events, and use those explanations to make useful predictions. There are generally 7 steps to the scientific method. This is a good flow chart of the scientific method. Note: There are many versions of the steps of the scientific method, but they are essentially all the same!

3. 1. Stating the problem2. Gathering information on the problem 1. Stating the problem is something that you want to find out. Example: Why did 10 people get sick with E.coli at Saturday’s picnic? 2. Gathering information on the problem? You must first Observe and gather facts! Observation: Everyone who got sick with E. coli ate the chicken, potato salad and/or ate ice cream within 72 hours. Inference: What does this suggest?

4. Observation Versus Inference • There are two types of data scientists gather: quantitative and qualitative. • When scientists gather information, they begin with observations or the process of recording information in a careful or orderly way. This is called Quantitative data. • Scientists also use data to make inferences. This is a logical interpretation based upon prior knowledge or experiences. This is called Qualitative data. Let’s start out easy and then test your skills with a few observation versus inference games!

5. Forming a Hypothesis Hypothesis – proposed solution or educated guess to the problem. They must be proposed in such a way that they can be tested. (or testable.) There can be multiple hypotheses or many solutions to a scientific problem! Example: Remember the bad picnic? 1. The chicken was bad (infected with E.coli) and made people sick. 2. The potato salad was bad (infected with E.coli) and made people sick. 3. The ice cream was bad (infected with E.coli) and made people sick. The Suspects!

6. 4. Performing experiments to test the Hypothesis 1 2 3 4 5 • We must test the hypothesis to determine whether or not it is correct or explains what is going on in our problem. • Testing is done through experiments. • Example: Compare the items that made people sick by growing samples of bacteria (E.coli) on culture plates resistant to other types of pathogen growth using sterile techniques. • Why is it important to have specific media?

7. 4. Experiment: Controls 1 E.coli 2 nothing • Controls – There are two types of controls in every experiment used as a basis of comparison. • Positive Control: Your anticipated outcome of the experiment. This control ensures that your experiment is working properly and/or there are not any outside factors influencing the outcome of your experiment. • Example: A pure sample of E.coli that made everyone sick from the picnic. • Outcome: A sample of E.coli will grow on this plate. • Negative Control: Contains no variables and should have no effect or outcome in your experiment. This control ensures that no contamination has occurred in your experiment. • Example: No sample of any food item added to the petri dish. • Outcome: Nothing should grow on this plate.

8. 4. Experiment: Variables In designing an experiment, only one variable is tested at a time with your positive and negative controls. Variable – the factor being tested Independent Variable – Factor you can manipulate Dependent Variable – Factor that responds to the manipulation and can be measured. Example: Samples of the three food items from the picnic. 3 Chicken 4 Potato salad 5 Ice cream

9. 5. Recording and Analyzing Data A) Data are Recorded observations and measurements. Data is usually shown in a table or chart. B) Then data is made into a graph to show trends. Makes information easier to see! We’ll conduct a graphing experiment later…

10. 6.Stating a conclusion7.Repeating the experiment 6. Once you have looked at your data, you can draw conclusions. Example: Which plate showed growth? What food was the culprit? What would you report based upon your outcome? Other Outcomes/Conclusions: What if nothing was wrong with the food at all? How would you revise your hypothesis and conduct another experiment? What if there was no growth on plate 1? What is there was growth on plate 2? 7. In order to ensure your data is accurate AND to that your hypothesis accurately explains what is scientifically going on, experiments will be constantly repeated. Why is this important?

12. Safety Goggles Used for Eye protection. The most common used safety item in the biology laboratory. Use when there are Chemicals, Flames or Heating. They give you protection against flying objects or toxic substances. If your eyes come into contact with a substance, use the eye wash immediately.

13. Poison Do not let it on your skin or inhale its vapor. Wash your hands after handling. Can cause death if eaten or drunk. Let your teacher know immediately if you come into direct contact. Always hold test tubes or flasks away from your nose and face and waft odors towards you.

14. Fire Hazard Wear safety goggles with fire hazards. Tie back loose hair and clothing. Ask your teacher about lighting and extinguishing fires during a lab.

15. Physical Safety This activity involves physical activity. Use caution to avoid injuring yourself and others. Follow all instructions from your teacher. Alert your teacher if there is any reason you should not participate in this activity.

16. Glassware Hazard Glassware is present and can cause injury. Glassware should be cleaned with each use to avoid contamination. Alert your teacher if there is any broken glassware. Broken glass goes in a special “sharps” container, not in the regular trash.

17. Sharp Object Scissors, scalpels, razor blades, pins, and knives are sharp so use care. Always direct sharp edges and points away from yourself and others. If you are cut or bleeding, let your teacher know immediately. Use only as directed.

18. Heat Hazard • Use an oven mitt or gloves when handling hot materials. • Use clamps or tongs to hold hot objects. • Always heat objects in a test tube away from you and others. • Hot plates, hot water and hot glassware can cause burns. • Glassware looks the same when hot or cold, so use care when heating any type of glass. • Rapid changes in glass temperature can cause it to expand, crack and/or explode! • Plastic tools should never be heated on a hot plate! • They will melt! • Never touch hot objects with your bare hands.

19. Corrosive Chemical Indicates an acid or other corrosive chemical. Wear gloves at all times and safety goggles! Avoid getting in skin or eyes. Do not inhale vapors. Wash your hands after lab activity.

20. Electrical Hazard Avoid electric shock. Never use electrical equipment around water or when your hands are wet. Be sure cords are untangled and unplugged when not in use.

21. Animal Safety • Treat live animals with care. • Be careful when dissecting preserved animals. • Wear safety goggles! • Wear latex gloves! • Wash your hands after lab.

23. Why Graph? When performing an experiment, a scientist must be able to record an immense amount of data andprocess that data into useful information. This is done by converting raw data into charts or tables. Then, the data must be graphed such that it can be interpreted by the public. Graphs are visual representations of data.

24. Part 1: Tables and Charts Tables and charts are created for organizing data from raw data. The chart should show how a trend occurs over several occurrences, (months, trials, categories, etc) or over time. Once data is organized, it can be graphed!

25. Part 2: Graphing DataA) Pie Graphs Pie graphs are useful in showing percentages. Displays how different categories are represented within a topic area. Sample: How many land does Asia take up in the world?

26. Part 2: Graphing Data B) Bar Graphs A bar graph is a way of showing relationships between variables, typically items that being compared. It contains an x and y axis. These are 2 lines that meet at a right angle. It uses a series of columns to display data. Example, how does the number of farms in 1910 compare with 1990? Notice: The x and y axis are always labeled. The graph has a title. The bars are vertical. The numbers on the Y axis are in sequence for an accurate comparison.

27. Part 2: Graphing DataC) Line Graphs A line graph shows the best relationship between 2 variables. Along the x-axis (horizontal) is the manipulated or independent variable. Along the y-axis (vertical) is the responding or dependent variable. Has one or more lines connecting a series of points. Notice: Time is on the x-axis (independent variable) Distance is on the y-axis (dependent variable) Distance and time are in sequence.

28. Constructing a graph Decide which variable to place along the x and y axis. Decide on a scale for your graph. Must be as large as possible within the limits of the paper and still include the largest item of data. Select your scale with ease of locating points, multiples of 1, 2, 5, or 10 are easiest. Your Turn! Flip on the back of your notes and let’s conduct a graphing experiment!

30. Organic Polymers Polymers – macromolecules made of repeating units called monomers. Four types: carbohydrates, lipids, nucleic acids, proteins. Monomers Polymer 2-3

31. Carbohydrates Carbohydrates – compounds made of carbon, hydrogen, and oxygen in a ratio usually 1 : 2 : 1. Energy source!!! Ex: sugars, starches, glycogen, cellulose Monosaccharides (monomer) (glucose) Polysaccharides (polymer) (starch) 2-3

32. Carbohydrates

33. Lipids Lipids – made of mostly carbon and hydrogen atoms. Fats, oils, waxes Three fatty acids and a glycerol Store energy, make membranes, waterproof 2-3

34. Lipids

35. Nucleic acids Nucleic acids – contain hydrogen, oxygen, carbon, nitrogen, and phosphorus. Carry genetic information Monomers = Nucleotides Ex: DNA and RNA 2-3

36. Proteins Proteins – contain carbon, hydrogen, oxygen, and nitrogen. Form bones/muscles, transport substances, fight disease, control reactions, regulate cell processes. 2-3

37. Proteins • Monomers = amino acids • Peptide bond – bond between amino acids.

40. What are Enzymes? Enzymes are proteins which act as biological catalysts. Their subunits are amino acids. Enzymes are used by cells to trigger and control chemical reactions. Without enzymes, several reactions in cells would never occur or happen to slowly to be useful.

42. What is activation energy? Activation energy is the amount of energy needed to start a chemical reaction.

43. Enzymes speed up chemical reactions by lowering their activation energy.

44. What is a substrate? Enzymes bind to molecules called substrates. These substrates are the reactants that are catalyzed by the enzyme.

45. Lock and Key Hypothesis Each protein has a specific shape, therefore enzymes bind to substrates based on shape. The site on the enzyme where the substrates bind is called the active site. Enzymes bind to the substrates based on their complementary shape.. The fit is so exact that the active site and substrates are compared to a “lock and key”.

46. How are enzymes affected by the reactions? Enzymes are NOT changed by the reactions they catalyze, therefore they are reusable!

47. Induce Fit Hypothesis Enzymes can change shape slightly to fit the substrate a little better (like a hand in glove).

48. How can enzymes be affected? Enzymes can be affected by temperature and pH. Temperatures outside the correct range can cause enzymes to break down or change shape. This break down is called denaturation. Therefore, enzymes in our body work best at 37°C (98.6°F) and at a pH between 6.5 to 7.5. Ex: Catalase is an enzyme that breaks down hydrogen peroxide. H2O2 → H2O + O2 (gas) A raw potato in H2O2 gives off O2. The boiled potato give no bubbles because the enzyme has changed due to heat.

49. Enzymes can turn On & Off Most cells contain proteins that turn enzymes on or off during critical stages of development.