Name:____________ Exam #1 Variables Pd:_________ 1. Which statement best describes a controlled experiment? A) It eliminates the need for dependent variables. B) It shows the effect of a dependent variable on an independent variable. C) It avoids the use of variables. D) It tests the effect of a single independent variable. 2. An investigation was designed to determine the effect of ultraviolet light on mold spore growth. Two groups of mold spores were grown under identical conditions, except one group was exposed only to ultraviolet light, while the other group was grown in total darkness. In this investigation, the group of mold spores grown without receiving any ultraviolet light is known as the A) control B) hypothesis C) dependent variable D) limiting factor 3. Which statement about the use of independent variables in controlled experiments is correct? A) A different independent variable must be used each time an experiment is repeated. B) The independent variables must involve time. C) Only one independent variable is used for each experiment. D) The independent variables state the problem being tested. 4. In a scientific investigation, after the question is defined, the next step is most likely A) B) C) D) formulating a hypothesis identifying needed equipment designing the experiment collecting the data 5. Which sentence represents a hypothesis? A) Environmental conditions affect the pollination of plants. B) Boil 100 milliliters of water, let it cool, and then add 10 seeds to the water. C) Is water depth in a lake related to available light in the water? D) A lamp, two beakers, and elodea plants are selected for the investigation. Date: 9/16/19 6. A biologist formulates a hypothesis, performs experiments to test his hypothesis, makes careful observations, and keeps accurate records of his findings. In order to complete this process, the biologist should A) adjust the data to support the hypothesis B) eliminate data that do not support the hypothesis C) write a research paper explaining his theories before performing his experiments, in order to gain funding sources D) evaluate the findings and, if necessary, alter the hypothesis based on his findings, and test the new hypothesis Pd:_________ 7. Base your answer to the following question on on the information below and on your knowledge of biology. An investigation is carried out to determine the effect of exercise on the rate at which a person can squeeze a clothespin In this investigation, the independent variable is the A) control C) rate of squeezing B) exercise D) number of participants 8. In an experiment, what should be the relationship between the control group and the experimental group? A) They should be different in size B) They should resemble each other in at least two respects C) They should not be similar in any respect D) They should be identical in all respects except one 9. 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 the A) experimental group B) limiting factor C) control D) indicator 10. Base your answer to the following question on the information below and on your knowledge of biology. An experiment was carried out to answer the question "Does the pH of water affect the growth of radish plants?" Two groups of ten radish plants were set up. One group was watered with water having a pH of 3.0, and the other group was watered with water having a pH of 7.0. Both groups of plants received the same amount and intensity of light, the same amount of water, and they were grown in the same type of soil. The heights of the radish plants were measured every 2 days for a period of 2 weeks. What was the dependent variable in this experiment? A) heights of the plants C) temperature of the water B) pH of the water D) type of soil Pd:_________ 11. Base your answer to the following question on the information and diagrams below and on your knowledge of biology. An experiment was performed to determine the effect of different mineral salts on plant growth. Forty pots containing identical plants were divided into four equal groups and placed in a well-lighted greenhouse. Each pot contained a nonmineral potting medium and one plant. Materials were then added to each experimental group of pots as shown What was added to the control group of pots? A) B) C) D) water, only nitrogen salts, only potassium salts, only potassium and phosphorus salts 12. How does the CONTROL GROUP setup in an experiment differ from the other setups in the same experiment? A) It tests a different hypothesis. B) It has more variables. C) It does not receive the experimental treatment (Independent Variable). D) It utilizes a different method of data collection. 13. A new concept that is tested in a scientific investigation is known as A) a theory C) an inference B) the hypothesis D) an observation 14. In the lab activity Making Connections, an experiment was designed to test the effect of exercise on the ability to squeeze a clothespin. The number of times the clothespin was squeezed served as the A) independent variable C) hypothesis B) dependent variable D) control Pd:_________ 15. In an appropriately designed experiment, a scientist is able to test the effect of A) B) C) D) a single variable multiple variables the hypothesis scientific observations Base your answers to questions 16 and 17 on the information and diagram below and on your knowledge of biology. The presence of air is believed to be important for root growth in bean plants. The apparatus available to conduct an investigation is shown below. There are enough bottles and other materials to have multiple setups. Air (for aeration) can be bubbled into the bottle through the rubber tube. Design an experiment to test the effect of aeration on the growth of roots of bean seedlings. In your answer, be sure to: 16. Describe how the control group will be treated differently from the experimental group. 17. Identify the dependent variable in the experiment. Pd:_________ 18. Base your answer to the following question on information and diagram below. An investigation was carried out using the two setups shown below. Other than the difference shown in the diagram, all other conditions were identical. a State one possible hypothesis that could be tested using these setups. b What data should be collected in order to test the hypothesis stated in question a? 19. Base your answer to the following question on the data table and information below and on your knowledge of biology. The data table describes various pH levels. A scientist is concerned about the effects of acid rain on newly fertilized fish eggs in lakes in the Adirondack Mountains of New York State. The scientist would like to investigate the hatching rates of these fish eggs in water at different acidic pH levels. The scientist designed an experiment that could show the effect of an acid pH on the hatching of these fish eggs. State two factors that must be kept the same in both the experimental groups and the control group.