4 Scientific investigations involve the following: questioningobservingexperimentingcollecting and organizing datafinding evidence and drawing conclusionsrepeating the experiment several timespeer review
6 Observations An observation is the act of gathering information. Observations are things or events that are made using any of the senses or tools, such as thermometer, graduated cylinders, balances, or rulers.
7 Two types of Observations: Qualitative datainformation that describes color, odor, shape or some other physical characteristicsin general, anything that relates to the five senseshow something looks, feels, sounds, tastes or smells
8 Aim: How do we explain characteristics of science? Do now: Brainstorming about the wordScience.Vocabulary: data, inferences,assumptionsopinions
10 Quantitative datanumerical information such as temperature, volume, pressure, time, the quantity of a substance formed, or how much of a substance is used uptells you how much, how little, how big, how tall, or how fast
16 How much have you learned? When heavy rains occur while apple orchards are in bloom, the apple crop the following fall is much smaller than normal. This information can best be described asA. an inferenceB. a hypothesisC. a predictionD. an observation
17 2. A student prepared the following list of steps for performing a laboratory investigation. She omitted one important step for completing the investigation. Using one or more complete sentences, state the procedure that is missing in the chart.
18 3. The following graph represents the results of an investigation of the growth of three identical bacterial cultures incubated at different temperatures.Which inference canbe made from the graph?A. Temperature is unrelatedto the reproductive rateof bacteria.B. Bacteria cannot growat a temperature of 5°C.C. Life activities in bacteriaslow down at high temperatures.D. Refrigeration will most likely slow the growth of thesebacteria.
19 4. Which of the steps listed below would be first in a scientific investigation? A. Perform the experiment.B. Analyze the experimental data.C. Formulate a hypothesis.D. Define the problem to be investigated.
20 5. A student performed an experiment involving two strains of microorganisms, strain A and strain B, cultured in various temperatures for 24 hours. The results of this experiment are shown in the following table.Based on the results, the student inferredthat strain A was more resistant tohigher temperatures than B. What, ifanything, must the student do for thisinference to be considered a reasonable conclusion?A. nothing, because this inference is a valid scientific factB. repeat this experiment several times and obtain similarresultsC. repeat this experiment several times using differentvariablesD. develop a new hypothesis
21 The Scientific Method a systematic approach used in scientific study an organized process used by scientists to do researchprovides a method for scientists to verify the work of others
23 Hypothesis a tentative explanation for what has been observed a prediction based upon both research and observation“Experiments cannot prove a hypothesis”
24 A good hypothesis...predicts the relationship between cause and effect in a way that can be testedcan determine the organization of an experimentcan also help determine what data to collect and how to interpret those datatypically written as “if-then” or “I think that”
25 Examples of Hypothesis Statements This hormone will make plants grow faster.If this hormone is applied to plant leaves, then the plant will grow faster.I think this hormone when applied to plant leaves will make the plant grow faster.
26 The presence of this chemical in our drinking water does not harm us. If this chemical is safe, then it will not harm us when it is added to our drinking water.I think the presence of chemical in our drinking water does not harm us.
27 Designing an Experiment What is an experiment?a set of controlled observations that test the hypothesisa series of trials that are done to support or refute (disprove) a hypothesisa set of controlled observations where the results can be duplicated and rational conclusions drawn
28 You suspect that applying the chemical X to plant leaves will increase the growth rate of the plant. Hypothesis: If X is applied to the leaves of plants, then the plants will grow more rapidly than those that do not have X applied to their leaves.
34 How much have you learned? 1. A new drug for the treatment of asthma is tested on 100 people. The people are evenly divided into two groups. One group is given the drug, and the other group is given a glucose pill. The group that is given the glucose pill serves as theA. experimental groupB. limiting factorC. controlD. indicator
35 2. A drug company tested a new medication before putting it on the commercial market. Pills without medication were given to 500 test subjects in group A, and pills with medication were given to 500 subjects in group B. In this experiment, the individuals in group A served as theA. host groupB. dependent variableC. controlD. hypothesis
36 3. In order to find the percentage of organic matter in soil from several locations, a student collected the samples, weighed them immediately, roasted them for several minutes in the flame of a Bunsen burner to burn off organic matter, and weighed them again. The student concluded that the difference between the first and second weights represented the weight of the organic matter in the soil. The most serious mistake that the student made in this experiment was inA. taking large samplesB. weighing the samples before roasting themC. failing to dry the samples before first weighing themD. assuming that roasting could remove the organic matter
37 4. In an investigation to determine the effects of environmental pH on the germination of dandelion seeds, 25 dandelion seeds were added to each of five petri dishes. Each dish contained a solution that differed from the others only in its pH, as shown in the table. All other environmental conditions were the same. The dishes were covered and observed for 10 days.Which is theindependentvariable?dependent
38 A. test for the presence of starch in living tissues 5. As part of a laboratory experiment, a thin slice of peeled raw potato weighing 10 grams is placed in an oven at 80°C. After 5 hours, the potato sample is removed from the oven and weighed again. The purpose of this experiment might beA. test for the presence of starch in living tissuesB. isolate cells in various stages of cell divisionC. determine the water content of potato tissueD. study the rate of photosynthesis in potatoes
39 THEORYan explanation that has been supported by many, many experimentsstill subject to new experimental data and can be modifiedlead to new conclusions
40 SCIENTIFIC LAW a relationship in nature supported by many experiments a concise statement or mathematical equation about a basic relationship or regularity of nature
41 Scientific inquiry involves the ability to use various methods of recording datarepresenting dataorganizing data
42 Data can be organized into: Diagramstableschartsgraphsequationsmatrices
46 A student was working on an investigation to measure the relative activity of an enzyme at various pH values. He collected the following data: pH 2, enzyme activity 10; pH 8, enzyme activity 50; pH 12, enzyme activity 10; pH 4, enzyme activity 20; pH 6, enzyme activity 40; pH 10, enzyme activity 40What is the independent variable in this experiment?
47 Organize the given data by filling in the table below: Construct a graph using the information in the table.
48 According to the data, this enzyme would probably work best at what pH values? A. 7 and 8B. 2 and 12C. 6 and 7D. 4 and 10
51 How much have you learned? 1. Which laboratory procedure would be best for demonstrating the effect of light intensity on the production of chlorophyll in pea plants?A. using 10 plants of different species, eachgrown in the same intensity of lightB. using 10 plants of different species, eachgrown in a different intensity of lightC. using 10 plants of the same species, eachD. using 10 plants of the same species, each
52 2. In an early trial of the Salk vaccine for polio, 1,830,000 school children participated. This original trial was an attempt to determine whether the Salk vaccine was effective in preventing polio. Of the 1,830,000 children involved, only 440,000 received the vaccine. The remainder were not given the vaccine because theyA. had a natural immunityB. already had polioC. served as controlD. were allergic to the vaccine
53 3. One ounce each of protein, carbohydrate, and fat are burned separately in a calorimeter to determine the Caloric content. The results are shown in the data table.Which statement represents a valid conclusion based on the data?A. An ounce of fat contains about twice as many Caloriesas an ounce of protein.B. Protein is a better energy food than carbohydrate.C. Carbohydrates, fats, and proteins all yieldapproximately the same number of Calories per unit ofweight.D. Proteins and carbohydrates provide the most Caloriesper ounce.
54 4. A scientific study showed that the depth at which some microscopic plants were found in a lake varied from day to day. On clear days, the plants were found as far as 6 meters below the surface of the water but were only 1 meter below the surface on cloudy days. Which hypothesis would these observations support?A. Light intensity affects the growth ofmicroscopic plants.B. Wind currents affect the growth of microscopicplants.C. Nitrogen concentration affects the growth ofD. Precipitation affects the growth of microscopic
55 5. Tomato plants in a garden are not growing well 5. Tomato plants in a garden are not growing well. The gardener hypothesizes that the soil is too acidic. To test this hypothesis accurately, the gardener could do which of the following?A. Plant seeds of a different kind of plant.B. Move the tomato plant to an area withless sunlight.C. Change the pH of the soil.D. Reduce the amount of water available tothe plant.
56 6. A scientist tested a hypothesis that white-tailed deer would prefer apples over corn as a primary food source. The findings of the test, in which the scientist claimed that the deer preferred apples, were published. Which research technique, if used by the scientist, might result in this claim being questioned?A. The scientist observed four different locationsat various times.B. The scientist observed a total of 500 deer in 20different locations at various times.C. The scientist observed 200 deer in variousnatural settings, but none in captivity.D. The scientist observed 300 deer in variouslocations in captivity, but none in naturalsettings.
57 7. The current knowledge concerning cells is the result of the investigations and observations of many scientists. The work of these scientists forms a well-accepted body of knowledge about cells. This body of knowledge is an example of aA. hypothesisB. controlled experimentC. theoryD. research plan
58 8. The data below summarizes the results of an investigation in which seeds from the same plant were grown under different conditions of temperature and relative humidity.Which conclusion can be drawn from the information in the data table?A. Color in this species is determined by genes,only.B. Many characteristics are not inherited.C. Mutations occur only when plants are grown atlow temperatures.D. There is an interaction between environmentand heredity.
59 9. Diagrams, tables, and graphs are used by scientist mainly to A. design a research plan for an experimentB. test a hypothesisC. organize a dataD. predict the independent variable
60 10. Scientific studies have indicated that there is a higher percentage of allergies in babies fed formula containing cow’s milk than in breast-fed babies. Which statement represents a valid inference made from these studies?A. Milk from cows causes allergic reactions in allinfants.B. Breast feeding prevents all allergies fromoccurring.C. There is no relationship between drinkingcow’s milk and having allergies.D. Breast milk most likely contains fewersubstances that trigger allergies.
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