Intro to Biology, Chapter 1 Quiz: The Scientific Method
A researcher has found a strong positive correlation between shoe size and reading ability in elementary students. The most likely explanation is that the correlation is an example of _________. - - - - - Answers: Common causation Cyclic causation Direct causality Reverse causality
Common causation _ _ _ _ _ Age determine shoe size (of children) and it is also a factor that affects reading ability. So both shoe size and reading ability are directly affected by age. This is an example of common causation.
Identify the null hypothesis. - The number of pets in a household is unrelated to the number of people. - Drawing lessons enhance the ability to catch a football in young children. - Driving the speed limit will conserve more gas than driving 5mph under the speed limit. - Eating chocolate increases exam scores.
The number of pets in a household is unrelated to the number of people. _ _ _ _ _ A null hypothesis(H0) states that there is no relationship between two phenomenon. "The number of pets in a household is unrelated to the number of people. " is the only option predicting no relationship. An alternative hypothesis predicts some relationship between measured phenomena. All the other options are examples of alternative hypotheses.
What is wrong with this experiment? In 1668 Francesco Redi did a series of experiments on spontaneous generation. He began by putting similar pieces of meat into 12 identical jars. Four jars were left open to the air, four were sealed, and four were covered with gauze (the gauze will exclude the flies while allowing the meat to be exposed to air). In both experiments, he monitored the jars and recorded whether or not maggots (young flies) appeared in the meat. In both experiments, flies appeared in all of the open jars and only in the open jars. - - - - - Answers: - This experiment does not have a control group. - There was no dependent variable. - The experiment does not have a question. - This experiment is a well-designed experiment and has nothing wrong with it.
This experiment is a well-designed experiment and has nothing wrong with it. _ _ _ _ _ (other than he could have had more replicates).
A controlled experiment ___. - - - - - Answers: keeps all variants constant proceeds slowly enough that a scientist can make careful records of the results tests the experimental and control groups under the same conditions is repeated many times to make sure the results are accurate
tests the experimental and control groups under the same conditions _ _ _ _ _ Any well-designed experiment should keep all variables constant, except for one. That is defined as the experimental variable. Then, the results provided from the control and experimental groups can be said to be affected by the variable that was changed.
Identify the dependent variable in this experiment: Researchers at the University of Awesomeness studying lumberjacks have discovered that the luxuriousness of a man's beard (measured as beard length) increases his efficiency at chopping wood. The longer the beard, the faster they can chop a cord of wood. The researchers believe that having a beard may make swinging an ax more aerodynamic, resulting in a more efficient swing. - - - - - Answers: - beard length - time to chop a cord of wood
time to chop a cord of wood _ _ _ _ _ If you came up with this phrase: "Time to cut a cord of wood depends on beard length." Draw an arrow back from 'depends'. That is the dependent variable: time. The independent variable is beard length.
What is the difference between hypotheses and theories in science? - - - - - Answers: - Theories are hypotheses that have been proven to be true anywhere in the universe. - Theories are proven true; whereas hypotheses are often falsified. - A theory is a hypothesis that has been supported by at least 10 different experiments. - Hypotheses are relatively narrow in their scope; whereas theories have broad explanatory power.
Hypotheses are relatively narrow in their scope; whereas theories have broad explanatory power. _ _ _ _ _ A hypothesis is a specific prediction about a specific phenomenon (i.e. If I begin running 20 minutes a day, in 3 months I will lose between 10 and 15 pounds.); whereas a theory is applicable across a much broader range of phenomena. Theories and hypotheses are never really said to be proven in science. To be "proven" they would have to be applicable in any circumstance in the universe. A theory that has been "proven" in science is known as a law. And there are only laws in physics and chemistry, not in biology. We just don't know enough about life to make scientific laws about the nature of life.
Which of the following best describes the scientific method? - - - - - Answers: - If my observations from a well-designed experiment are accurate, I can expect my results to support my hypothesis. - If I generate a testable hypothesis, tests and observation will support it. - If my hypothesis is supported, then my theory is proven. - If my hypothesis is correct, I can expect certain results from a well-designed experiment.
If my hypothesis is correct, I can expect certain results from a well-designed experiment. _ _ _ _ _ In the case where a well-designed experiment is conducted, the hypothesis is either "supported" or "fails to be supported" by the results. In this manner, the hypothesis predicts what the results should look like (how they are expected to turn out).
Pasteur's results showed that _____. - - - - - Answers: - when growth medium is not contaminated by preexisting cells, the growth medium remains sterile if isolated - when growth medium is sterilized by boiling, it remains sterile even if new cells are introduced - when growth medium is not contaminated by preexisting cells, cells still grow there - with enough time, any sterile environment will become contaminated with cells even if isolated
when growth medium is not contaminated by preexisting cells, the growth medium remains sterile if isolated _ _ _ _ _ For a long time, it was thought that organisms spontaneously generated. For example, a steak left out would spontaneously generate. Pasteur's experiment was one of the first to disprove this hypothesis
Given the following information, which of these hypotheses would be supported? In our analysis, we compared the effects of hand lotion on hand bacterial diversity. We split our subjects into two groups. For both groups we collected a bacterial swab from their hands. The experimental group applied the hand lotion, while the control group did not. After the experimental group applied the lotion and it was dry, we collected a second bacterial swab from all subjects. Below is the data analysis. control group (no hand lotion) | mean change in bacterial diversity = 0.5 experimental group (hand lotion) | mean change in bacterial diversity = -1.3 The control group that did not receive hand lotion had an average increase in bacterial diversity of 0.5 species, whereas the experimental group had an average decrease of -1.3 species. The p-value of this analysis is 0.07. This leads us to conclude: _________. - - - - - Answers: Application of hand lotion does not affect bacterial diversity. Application of hand lotion decreases bacterial diversity. Application of hand lotion increases bacterial diversity.
Application of hand lotion does not affect bacterial diversity. _ _ _ _ _ In this case the p-value is higher than 0.05, therefore this study shows no significant difference between the means of the control and experimental groups. Therefore the conclusion is there is no relationship between application of hand lotion and change in bacterial diversity.
What type of experiment is this? In 1854, a major outbreak of cholera struck a neighborhood in London. Within three days 127 people near Broad Street died. By the end of the outbreak 616 people died. The physician John Snow identified the source of the outbreak as the nearest public water pump, using a map of deaths and illness that revealed a cluster of cases around the pump. In this example, Snow discovered a strong association between the use of the water and deaths and illnesses due to cholera. Snow found that the Southwark and Vauxhall Waterworks Company, which supplied water to districts with high attack rates, obtained the water from the Thames downstream from where raw sewage was discharged into the river. By contrast, districts that were supplied water by the Lambeth Waterworks Company, which obtained water upstream from the points of sewage discharge, had low attack rates. - - - - - Answers: - controlled experiment - natural experiment
natural experiment
