Chemistry Chapter 1 Homework 1-2

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.