Lab Skills

A student conducted an original, well-designed experiment, carefully following proper scientific procedure. In order for the conclusions to become generally accepted, the experiment must

•  contain several experimental variables
• be repeated to verify the reliability of the data
•  support the original hypothesis
•  be conducted by a scientist

A study was conducted using two groups of 10 plants of the same species. During the study, the plants were placed in identical environmental conditions. The plants in one group were given a growth solution every 3 days.The heights of the plants in both groups were recorded at the beginning of the study and at the end of a 3-week period. The data showed that the plants given the growth solution grew faster than those not given the solution. When other researchers conduct this study to test the accuracy of the results, they should

• give growth solution to both groups
• make sure the conditions are identical to those in the first study
• give an increased amount of light to both groups of plants
• double the amount of growth solution given to the first group

A biologist in a laboratory reports a new discovery based on experimental results. If the experimental results are valid, biologists in other laboratories should be able to

• repeat the same experiment with a different variable and obtain the same results
• perform the same experiment and obtain different results
• repeat the same experiment and obtain the same results
• perform the same experiment under differentexperimental conditions and obtain the same results

Which procedure must be followed for the results of an experiment to be considered valid?

• The experiment must be repeated a number of times and yield similar results.
• After one trial, the results of the experiment must be published.
• The results must be expressed in the form of a table or graph.
• The data must include metric measurements.

A student used a microscope like the one represented in the photo to observe cell division in onion cells. The part of the microscope that should be adjusted in order to better view the onion cells while using high power is

• A
• B
• C
• D

A broad body of evidence, subject to revisions, supported by different kinds of scientific investigations and often involving the contributions of scientists from different disciplines is necessary to develop

• an inference
• a fact
• a theory
• a prediction

A student wanted to investigate the effect of light on the rate of ripening of tomatoes. She set up four pots of the same size with identical amounts of soil, water, and type of tomato plants. Each plant was exposed to a different intensity of light as shown in the table. To report the final results, which label would be most appropriate for the third column of the data table?

• Height of Tomato Plants (cm)
• Average Ripening Time (days)
• Average Weight of Tomatoes per Plant (grams)
• Acidity of Tomatoes (pH)
  

A student wanted to investigate the effect of light on the rate of ripening of tomatoes. She set up four pots of the same size with identical amounts of soil, water, and type of tomato plants. Each plant was exposed to a different intensity of light as shown in the table to the right.The independent variable in this experiment is the

• type of tomato plant  
• amount of soil provided
• color of tomatoes
  
• light intensity

Which statement best expresses a basic scientific assumption?

• Interpretation of experimental results has provided explanations for all natural phenomena.
  
• If a conclusion is valid, similar investigations by other scientists should result in the same conclusion.
  
• For any conclusion to be valid, the design of the experiment requires that only two groups be compared.
  
• After a scientist formulates a conclusion based on an experiment, no further investigation is necessary.
  

The diagram represents a specimen in the low-power field of view of a compound light microscope. If the slide is not moved, which view best represents the way the specimen will look when the high-power objective lens is switched into place?

• lower right edge
• top edge
• completely in the center
• left edge