Chemistry Chapter 1 Homework 1-2

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Chemistry Chapter 1 Homework 1-2 - Quiz

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Questions and Answers
  • 1. 

    In 1928, Sir Alexander Fleming was studying Staphylococcus bacteria growing in culture dishes. He noticed that a mold called Penicillium was also growing in some of the dishes. As shown in the illustration below, Petri dish A represents a dish containing only Staphylococcus bacteria. In dishes containing thePenicillium mold, represented by Petri dish B below, Fleming noticed that a clear area existed around the mold because all the bacteria in this area had died. In the culture dishes without the mold, no clear areas were present. Fleming suggested that the mold was producing a chemical that killed the bacteria. He decided to isolate this substance and test it to see if it would kill bacteria. Fleming grew some Penicillium mold in a nutrient broth. After the mold grew in the broth, he removed all the mold from the broth and added the broth to a culture of bacteria. All the bacteria died.Which of the following statements is a reasonable expression of Fleming's hypothesis?

    • A.

      Nutrient broth kills bacteria.

    • B.

      There are clear areas around the Penicillium mold where Staphylococcus doesn't grow.

    • C.

      Mold kills bacteria.

    • D.

      Penicillium mold produces a substance that kills Staphylococcus.

    • E.

      Without mold in the culture dish, there were no clear areas in the bacteria.

    Correct Answer
    D. Penicillium mold produces a substance that kills StapHylococcus.
    Explanation
    Fleming's hypothesis is that the Penicillium mold produces a substance that kills Staphylococcus bacteria. This is based on his observation that when the mold was present in the culture dish, there was a clear area around it where the bacteria did not grow. He then conducted an experiment where he grew the mold in a nutrient broth and added the broth to a culture of bacteria, resulting in the death of all the bacteria. This supports his hypothesis that the mold produces a substance that kills the bacteria.

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  • 2. 

    Using the information from the previous question:  Fleming grew Penicillium in broth, removed the Penicillium, and poured the broth into culture dishes containing bacteria to see if the broth would kill the bacteria. What step in the scientific method does this represent?

    • A.

      Collecting and organizing data

    • B.

      Making a hypothesis

    • C.

      Testing a hypothesis by experiment

    • D.

      Rejecting the old hypothesis and making a new one

    • E.

      None of these

    Correct Answer
    C. Testing a hypothesis by experiment
    Explanation
    This step represents testing a hypothesis by experiment. Fleming conducted an experiment to test his hypothesis that the broth containing Penicillium would kill the bacteria. By pouring the broth into culture dishes containing bacteria, he was able to observe the effect of the broth on the bacteria and determine whether his hypothesis was supported or not. This step is an essential part of the scientific method as it allows scientists to gather empirical evidence to support or refute their hypotheses.

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  • 3. 

    A scientific investigation is not valid unless every step in the scientific method is present and carried out in the exact order listed in this chapter.

    • A.

      True

    • B.

      False

    Correct Answer
    B. False
    Explanation
    The statement that a scientific investigation is not valid unless every step in the scientific method is present and carried out in the exact order listed in the chapter is false. While the scientific method provides a structured approach to conducting scientific investigations, it is not necessary for every step to be followed in a strict order for an investigation to be valid. Different scientific investigations may require variations in the order or inclusion/exclusion of certain steps based on the nature of the research question and the available resources. Flexibility and adaptation are important aspects of the scientific process.

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  • 4. 

    Which of the following is closest in meaning to the word “hypothesis”?

    • A.

      Fact

    • B.

      Law

    • C.

      Formula

    • D.

      Suggested explanation

    • E.

      Conclusion

    Correct Answer
    D. Suggested explanation
    Explanation
    The word "hypothesis" refers to a proposed explanation or theory that is based on limited evidence or assumptions. It is an educated guess or a supposition that can be tested and verified through further investigation. Therefore, the closest word in meaning to "hypothesis" would be "suggested explanation," as it captures the idea of proposing a possible solution or interpretation.

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  • 5. 

    Why do scientists sometimes discard theories?

    • A.

      The steps in the scientific method were not followed in order.

    • B.

      Public opinion disagrees with the theory.

    • C.

      The theory is opposed by the church.

    • D.

      Contradictory observations are found.

    • E.

      Congress voted against it.

    Correct Answer
    D. Contradictory observations are found.
    Explanation
    Scientists sometimes discard theories when contradictory observations are found. This means that new evidence or data is discovered that does not align with the predictions or explanations provided by the theory. In order to maintain the integrity of the scientific process, scientists must revise or discard theories that are no longer supported by empirical evidence. This allows for the advancement of knowledge and the development of more accurate explanations for natural phenomena.

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  • 6. 

    Gary noticed that two plants of the same type were different in size after three weeks, even though they were initially the same size when his mother planted them on the same day. Since the larger plant was in the full sun all day and the smaller plant was in the shade of a tree for most of the day, Gary believed that the sunshine was responsible for the difference in plant size. In order to test this, Gary bought ten small plants of the same size and type. He also made sure they have the same amount and type of soil. Gary then built a frame to hold a canvas roof over five of the plants, while the other five were nearby but out in the sun. Gary was careful to make sure that each plant received exactly the same amount of water and plant food every day.Which of the following is a reasonable statement of Gary's hypothesis?

    • A.

      Different plants have different characteristics

    • B.

      Plants that get more sunshine grow larger than plants that get less sunshine.

    • C.

      Plants that grow in the shade grow larger

    • D.

      Plants that don't receive water will die.

    • E.

      Plants that receive the same amount of water and plant food will grow the same amount.

    Correct Answer
    B. Plants that get more sunshine grow larger than plants that get less sunshine.
    Explanation
    Gary's hypothesis is that plants that receive more sunshine will grow larger than plants that receive less sunshine. This hypothesis is based on his observation that the larger plant was in the full sun all day while the smaller plant was in the shade of a tree for most of the day. To test this hypothesis, Gary sets up an experiment where he provides the same amount of water and plant food to both sets of plants but manipulates the amount of sunshine they receive by building a frame to create shade for some plants and leaving others out in the sun.

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  • 7. 

    What scientific reason might Gary have for insisting that the container size for the all plants be the same?

    • A.

      Gary wanted to determine if the size of the container would affect the plant growth.

    • B.

      Gary wanted to make sure the size of the container did not affect differential plant growth in his experiment.

    • C.

      Gary wanted to control how much plant food his plants received.

    • D.

      Gary wanted his garden to look organized.

    • E.

      There is no possible scientific reason for having the same-sized containers.

    Correct Answer
    B. Gary wanted to make sure the size of the container did not affect differential plant growth in his experiment.
    Explanation
    By insisting that the container size for all plants be the same, Gary is eliminating the variable of container size as a potential factor that could affect plant growth. This allows him to focus solely on the impact of other variables, such as plant food or environmental conditions, on plant growth. By controlling for container size, Gary can ensure that any differences observed in plant growth are due to these other factors and not influenced by the size of the container.

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  • 8. 

    What scientific reason might Gary have for insisting that all plants receive the same amount of water every day?

    • A.

      Gary wanted to test the effect of shade on plant growth, and therefore he wanted to have no variables other than the amount of sunshine on the plants.

    • B.

      Gary wanted to test the effect of the amount of water on plant growth.

    • C.

      Gary's hypothesis was that water quality was affecting plant growth.

    • D.

      Gary was conserving water.

    • E.

      There is no possible scientific reason for having the same amount of water for each plant every day.

    Correct Answer
    A. Gary wanted to test the effect of shade on plant growth, and therefore he wanted to have no variables other than the amount of sunshine on the plants.
    Explanation
    Gary wanted to test the effect of shade on plant growth, and therefore he wanted to have no variables other than the amount of sunshine on the plants. By ensuring that all plants receive the same amount of water every day, Gary can eliminate water as a variable and focus solely on the impact of shade on plant growth. This allows for a more accurate and controlled experiment, as any differences in plant growth can be attributed solely to the amount of shade received.

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  • 9. 

    What was the variable being tested in Gary's experiment?

    • A.

      The amount of water

    • B.

      The amount of plant food

    • C.

      The amount of soil

    • D.

      The amount of sunshine

    • E.

      The type of soil

    Correct Answer
    D. The amount of sunshine
    Explanation
    In Gary's experiment, he was testing the effect of different variables on plant growth. The options given include the amount of water, plant food, soil, sunshine, and type of soil. Out of these options, the correct answer is the amount of sunshine. This means that Gary was specifically examining how varying amounts of sunshine affected the growth of the plants in his experiment.

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  • 10. 

    Which of the following factors did Gary not control in his experimental setup that may be varying?

    • A.

      Individual plant variation

    • B.

      Soil temperature due to the different colors of the containers

    • C.

      Water loss due to evaporation from the soil

    • D.

      The effect of insects, which may attack one set of plants but not the other

    • E.

      All of the above are possible factors that Gary did not control

    Correct Answer
    E. All of the above are possible factors that Gary did not control
    Explanation
    Gary did not control individual plant variation, soil temperature due to the different colors of the containers, water loss due to evaporation from the soil, and the effect of insects, which may attack one set of plants but not the other. These factors may vary and could potentially affect the outcome of the experiment. Therefore, all of the above are possible factors that Gary did not control.

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  • 11. 

    When a mosquito sucks blood from its host, it penetrates the skin with its sharp beak and injects an anti-coagulant so that the blood will not clot. It then sucks some blood and removes its beak. If the mosquito carries disease-causing microorganisms, it injects these into its host along with the anti-coagulant. It was assumed for a long time that the typhus virus was injected by the louse (singular for lice) when sucking blood in a manner similar to the mosquito. This turned out not to be true. The infection is not in the saliva of the louse but in the feces. The disease is thought to be spread when louse feces come in contact with scratches or bite wounds on the host's skin. A test of this was carried out in 1922 when two workers fed infected lice on a monkey, taking great care that no louse feces came into contact with the monkey. After two weeks, the monkey had not become ill with typhus. The workers then injected the monkey with typhus, and the monkey became ill within a few days. Why did the workers inject the monkey with typhus near the end of the experiment?

    • A.

      To prove that the lice carried the typhus virus

    • B.

      To prove the monkey was similar to man

    • C.

      To prove that the monkey was not immune to typhus

    • D.

      To prove that mosquitoes were not carriers of typhus

    • E.

      To demonstrate that the workers were mean

    Correct Answer
    C. To prove that the monkey was not immune to typHus
    Explanation
    The workers injected the monkey with typhus near the end of the experiment to prove that the monkey was not immune to typhus. This was done to confirm that the previous negative result of the monkey not becoming ill after being exposed to infected lice was not due to the monkey's immunity to the disease. By injecting the monkey with typhus and observing its subsequent illness, the workers demonstrated that the monkey was susceptible to the disease and therefore the previous negative result was not due to immunity.

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  • 12. 

    When a theory has been known for a long time, it becomes a law.

    • A.

      True

    • B.

      False

    Correct Answer
    B. False
    Explanation
    This statement is false. The progression from theory to law is not based on the length of time a theory has been known. In science, a theory is a well-substantiated explanation of some aspect of the natural world that is based on a body of evidence and has undergone extensive testing and scrutiny. A scientific law, on the other hand, is a statement that describes a fundamental principle or relationship observed in nature. The distinction between theories and laws lies in their scope and level of generality, not in the amount of time they have been known.

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  • 13. 

    During Pasteur's time, anthrax was a widespread and disastrous disease for livestock. Many people whose livelihood was raising livestock lost large portions of their herds to this disease. Around 1876, a horse doctor in eastern France named Louvrier claimed to have invented a cure for anthrax. The influential men of the community supported Louvrier's claim of having cured hundreds of cows of anthrax. Pasteur went to Louvrier's hometown to evaluate the cure. The cure was explained to Pasteur as a multi-step process during which: 1) the cow was rubbed vigorously to make her as hot as possible; 2) long gashes were cut into the cows skin; 3) turpentine was poured into the cuts; 4) an inch-thick coating of cow manure mixed with hot vinegar was plastered onto the cow; and 5) the cow was completely wrapped in a cloth. Since some cows recover from anthrax with no treatment, performing the cure on a single cow would not be conclusive, so Pasteur proposed an experiment to test Louvrier's cure. Four healthy cows were to be injected with anthrax microbes. After the cows became ill, Louvrier would pick two of the cows (A and B) and perform his cure on them, while the other two cows (C and D) would be left untreated. The experiment was performed, and after a few days, one of the untreated cows died and the other got better. Of the cows treated by Louvrier's cure, one cow died and the other got better. In this experiment, what was the purpose of infecting cows C and D?

    • A.

      To give Louvrier more than two cows to choose from

    • B.

      To make sure the injection actually contained anthrax

    • C.

      To serve as experimental controls (a comparison of treated to untreated cows)

    • D.

      To kill as many cows as possible

    Correct Answer
    C. To serve as experimental controls (a comparison of treated to untreated cows)
    Explanation
    The purpose of infecting cows C and D in the experiment was to serve as experimental controls, allowing for a comparison between the treated cows (A and B) and the untreated cows. By having a control group, it becomes possible to determine the effectiveness of Louvrier's cure for anthrax. If all four cows were treated and got better, it would be difficult to determine whether the cure was effective or if the cows would have recovered on their own. By having a comparison group, it becomes clear whether the treatment had any impact on the outcome of the illness.

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  • 14. 

    A hypothesis is:

    • A.

      A description of a consistent pattern in observations.

    • B.

      An observation that remains constant.

    • C.

      A theory that has been proven.

    • D.

      A tentative explanation for a phenomenon.

    Correct Answer
    D. A tentative explanation for a pHenomenon.
    Explanation
    A hypothesis is a tentative explanation for a phenomenon. It is a proposed explanation based on limited evidence or observations that can be tested and further investigated. It is not a proven theory, but rather a starting point for scientific inquiry. Hypotheses are used to generate predictions and design experiments to gather more data and evidence to support or refute the proposed explanation.

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  • 15. 

    A scientific law is:

    • A.

      A description of a consistent pattern in observations.

    • B.

      An observation that remains constant.

    • C.

      A theory that has been proven.

    • D.

      A tentative explanation for a phenomenon.

    Correct Answer
    A. A description of a consistent pattern in observations.
    Explanation
    A scientific law is a description of a consistent pattern in observations. It is a statement or equation that summarizes a natural phenomenon and is based on repeated experimental evidence. Scientific laws are considered to be universal and apply to all instances of a particular phenomenon. Unlike theories, which are explanations for how or why something happens, laws simply describe what happens. They are derived from extensive observations and experiments and provide a foundation for further scientific research and understanding.

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  • 16. 

    A number of people became ill after eating oysters in a restaurant. Which of the following statements is a hypothesis about this occurrence?

    • A.

      Everyone who ate oysters got sick.

    • B.

      People got sick whether the oysters they ate were raw or cooked.

    • C.

      Symptoms included nausea and dizziness.

    • D.

      The cook felt really bad about it.

    • E.

      Bacteria in the oysters may have caused the illness.

    Correct Answer
    E. Bacteria in the oysters may have caused the illness.
    Explanation
    The correct answer suggests a hypothesis that the illness may have been caused by bacteria present in the oysters consumed by the people. This hypothesis implies that the bacteria could be the potential source of the illness and further investigation is needed to confirm this assumption.

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  • 17. 

    Which statement best describes the reason for using experimental controls?

    • A.

      Experimental controls eliminate the need for large sample sizes.

    • B.

      Experimental controls eliminate the need for statistical tests.

    • C.

      Experimental controls reduce the number of measurements needed.

    • D.

      Experimental controls allow comparison between groups that are different in only one variable.

    Correct Answer
    D. Experimental controls allow comparison between groups that are different in only one variable.
    Explanation
    Experimental controls allow comparison between groups that are different in only one variable. This means that all other variables are kept constant or controlled in order to isolate the effect of the one variable being tested. By doing so, researchers can determine whether any observed differences between the groups are due to the manipulated variable or other factors. This helps to establish a cause-and-effect relationship and increases the internal validity of the experiment. It also allows for more accurate and meaningful interpretation of the results.

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  • 18. 

    A student decides to set up an experiment to determine the relationship between the growth rate of plants and the presence of detergent in the soil. He sets up ten seed pots. In five of the seed pots, he mixes a precise amount of detergent with the soil. The other five seed pots have no detergent in the soil. The five seed pots with detergent are placed in the sun, and the five seed pots with no detergent are placed in the shade. All ten seed pots receive the same amount of water as well as the same number and type of seeds. He grows the plants for two months and charts the growth every two days. What is wrong with his experiment?

    • A.

      The student has too few pots.

    • B.

      The student has two variables different between the groups.

    • C.

      The student did not add detergent to all ten pots.

    • D.

      The student has no experimental control on the soil.

    Correct Answer
    B. The student has two variables different between the groups.
    Explanation
    The student has two variables different between the groups. This is a problem because in an experiment, it is important to only change one variable at a time in order to determine its effect on the outcome. In this case, the student is testing the growth rate of plants in relation to the presence of detergent in the soil. However, by also placing the seed pots with detergent in the sun and the seed pots without detergent in the shade, the student is introducing another variable (sunlight) that could potentially affect the growth rate. This makes it difficult to determine whether any observed differences in growth rate are due to the presence of detergent or the difference in sunlight exposure.

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  • 19. 

    A scientist plants two rows of corn for experimentation. She puts fertilizer on row 1 but does not put fertilizer on row 2. Both rows receive the same amount of sun and water. She checks the growth of the corn over the course of five months. What is acting as the control in this experiment?

    • A.

      The corn without fertilizer

    • B.

      The corn with fertilizer

    • C.

      The amount of water

    • D.

      The height of the corn plants

    Correct Answer
    A. The corn without fertilizer
    Explanation
    The control in this experiment is the corn without fertilizer. The scientist is comparing the growth of the corn with fertilizer to the growth of the corn without fertilizer. By keeping all other variables constant (such as the amount of sun and water), the scientist can determine the effect of the fertilizer on the growth of the corn.

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  • 20. 

    If you have a control group for your experiment, which of the following is true?

    • A.

      There can be more than one difference between the control group and the test group but no more than three differences, or else the experiment is invalid.

    • B.

      The control group and the test group may have many differences between them.

    • C.

      The control group must be identical to the test group except for one variable.

    • D.

      None of these are true.

    Correct Answer
    C. The control group must be identical to the test group except for one variable.
    Explanation
    The correct answer is that the control group must be identical to the test group except for one variable. This is because in an experiment, the purpose of the control group is to serve as a baseline for comparison. By keeping all variables constant except for the one being tested, any differences observed between the control group and the test group can be attributed to the variable being tested. This allows researchers to determine the specific effects of that variable on the outcome of the experiment.

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  • 21. 

    If the hypothesis is rejected by the experiment, then:

    • A.

      The experiment may have been a success.

    • B.

      The experiment was a failure.

    • C.

      The experiment must be poorly designed.

    • D.

      The experiment didn't follow the scientific method.

    Correct Answer
    A. The experiment may have been a success.
    Explanation
    If the hypothesis is rejected by the experiment, it does not necessarily mean that the experiment was a failure or poorly designed. It simply means that the results obtained from the experiment did not support the hypothesis. This could happen due to various reasons such as limitations in the experimental setup, unexpected variables, or errors in data collection. Therefore, it is possible that despite the rejection of the hypothesis, the experiment may still have been successful in providing valuable insights or generating new questions for further research.

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  • 22. 

    A well-substantiated explanation of an aspect of the natural world is a:

    • A.

      Theory.

    • B.

      Law.

    • C.

      Hypothesis.

    • D.

      None of the above.

    Correct Answer
    A. Theory.
    Explanation
    A well-substantiated explanation of an aspect of the natural world is a theory. A theory is a well-established and widely accepted explanation that is supported by evidence and has been extensively tested. It is based on observations, experiments, and data, and provides a framework for understanding and predicting natural phenomena. Unlike a hypothesis, which is a proposed explanation that requires further testing, a theory has undergone rigorous scrutiny and has withstood the test of time. A theory is different from a law, as a law describes a fundamental principle or relationship that has been repeatedly observed and is universally applicable. Therefore, the correct answer is theory.

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  • Mar 21, 2023
    Quiz Edited by
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