1.
Chan wants to determine how much the mass of fungus growing on a nutrient agar plate changes over an 8 hr period. What is the most appropriate unit of measure for him to use?
Correct Answer
C. Milligram
Explanation
The most appropriate unit of measure for Chan to use in determining the mass of fungus growing on a nutrient agar plate over an 8 hr period is milligram. Milligram is a smaller unit of measure compared to kilogram and is commonly used for measuring small masses. Since the mass of fungus is likely to be relatively small, using milligrams would provide a more precise and accurate measurement. Kilometer and millimeter are units of measure for length and are not suitable for measuring mass.
2.
What is the best definition of a scientific theory?
Correct Answer
A. An explanation of how and why a natural pHenomenon behaves teh way it does
Explanation
A scientific theory is the best definition because it provides an explanation for how and why a natural phenomenon behaves in a certain way. It goes beyond simply describing an invariable relationship or making a speculation or guess about nature. A scientific theory is based on evidence and extensive research, and while it may not be proven as an absolute fact, it is supported by a significant amount of empirical data.
3.
A scientist studies the effects that barnyard grass, a weed, has on the growth of rice, other weeds, and insects. The barnyard grass and other weeds, rice, and insects make up whihc level of biological organization?
Correct Answer
B. Community
Explanation
The correct answer is community because a community refers to all the different species that interact and live together in a specific area. In this scenario, the barnyard grass, other weeds, rice, and insects are all different species that are being studied by the scientist. They are all part of the same community as they interact and coexist in the same environment.
4.
Lydia works in a flower shop after school. She notices that the hydrangeas in Container 1 have pink blossoms, while the hydrangeas in Container 2 have blue blossoms. She makes sure they all recieve the same amount of light and water. Her boss tells her that the flowers were all grown from the same seed variety. Lydia discovers, after testing the soil, that although the same type of soil was used, the soil in Container 1 has a pH of 6.0, and the soil in Container 2 has a pH of 5.0.
Lydia most likely conducted her investigation to answer what question about hydrangeas?
Correct Answer
A. How does the chemistry of the soil affect the color of hydrangea blossoms?
Explanation
The correct answer is "How does the chemistry of the soil affect the color of hydrangea blossoms?" because Lydia conducted her investigation to understand why the hydrangeas in Container 1 have pink blossoms while those in Container 2 have blue blossoms. She tested the soil and discovered that the pH levels were different in each container, indicating that the chemistry of the soil affects the color of the hydrangea blossoms. This suggests that the soil's pH level plays a role in determining the color of the hydrangea blossoms.
5.
Which experimental design would provide scientists with the best data for investigating which type of feed yields the greatest gain in lean muscle mass in cattle?
Correct Answer
B. Test 5 similar groups of cows with 5 different feed mixtures and measure their weight gain at the end of a 6-week trial.
Explanation
Testing 5 similar groups of cows with 5 different feed mixtures and measuring their weight gain at the end of a 6-week trial would provide scientists with the best data for investigating which type of feed yields the greatest gain in lean muscle mass in cattle. This design allows for a direct comparison between different feed mixtures, as each group of cows is exposed to a different feed. By measuring weight gain, scientists can determine which feed mixture leads to the highest increase in lean muscle mass. Additionally, using similar groups of cows ensures that any differences in weight gain can be attributed to the feed mixture rather than other factors.
6.
Shown below is a growth curve for Paramecium grown in a 1.0 L flask containing pond water at 20oC. The pond water is continually filtered to remove waste products, and nutrients are added at a constant rate.
How could the experiment be modified to determine whether the temperature influences the population size of Paramecium?
Correct Answer
C. Repeat the procedures described using 2 flasks; incubate 1 flask at 15oC and the other at 25oC.
Explanation
To determine whether temperature influences the population size of Paramecium, it is necessary to compare the growth of Paramecium at different temperatures. By repeating the procedures described using 2 flasks and incubating one flask at 15oC and the other at 25oC, it allows for a direct comparison between the two temperature conditions. This will provide data on the population size of Paramecium at different temperatures and allow for the evaluation of any temperature-dependent effects on population growth.
7.
Scientists collected data on the height and weight of individuals in a population. They recorded their results in this scatterplot.
What is the most accurate conclusion regarding the relationship between height and weight?
Correct Answer
D. There us a positive relationship between height and weight.
Explanation
The scatterplot shows that as height increases, weight also tends to increase. This suggests a positive relationship between height and weight, indicating that taller individuals tend to be heavier.
8.
Paul and Simon want to determine who is more fit. They decide to run in place for 5 minutes and then measure their blood pressures to see whose returns to notrmal most quickly. They record the data in this table.
Paul told Simon that the heart pumps more blood during exercise than at rest. How do the experiment’s results support Paul’s statement?
Correct Answer
D. Exercise increases both the pulse and the systolic pressure.
Explanation
The experiment's results support Paul's statement because exercise increases both the pulse and the systolic pressure. This can be seen in the table where both Paul and Simon's pulse and systolic pressure increase after running in place for 5 minutes. This indicates that the heart is pumping more blood during exercise, as the pulse and systolic pressure are higher than at rest.
9.
A researcher counted the number of eggs a single fruit fly laid in 24 hrs for 5 days and recorded the findings in this table.
What is the average number of eggs laid per day over the 5 days?
Correct Answer
B. 10
Explanation
The average number of eggs laid per day over the 5 days is 10. This can be calculated by adding up the total number of eggs laid over the 5 days (50) and dividing it by the number of days (5). This gives us an average of 10 eggs laid per day.
10.
The graph represents the average fastest speed of 5 animals recorded in one study.
Based on the graph, which species is approximately 1/3 as fast as the cheetah?
Correct Answer
A. ElepHant
Explanation
The graph shows the average fastest speed of 5 animals, and we need to find the species that is approximately 1/3 as fast as the cheetah. By comparing the heights of the bars, we can see that the cheetah has the highest bar, indicating it is the fastest. Among the given options, the elephant has a bar that is approximately 1/3 the height of the cheetah's bar, suggesting that the elephant is approximately 1/3 as fast as the cheetah. Therefore, the answer is elephant.
11.
Ella told her sister the sun would set at 6:30 p.m. and there would be a full moon on Thursday night.
Under which basic assumption of science is she operating?
Correct Answer
A. Nature is orderly.
Explanation
Ella's statement about the sun setting at 6:30 p.m. and there being a full moon on Thursday night implies that she believes in the regularity and predictability of natural phenomena. This aligns with the basic assumption of science that nature is orderly, meaning that there are consistent patterns and laws governing the behavior of the natural world. Ella's confidence in making these predictions suggests that she expects the sun to set at the same time each day and the occurrence of a full moon on a specific night is not random but follows a predictable pattern.
12.
Ming is having trouble sleeping and decides to participate in a study to determine whether a certain medication helps people sleep. There are 30 volunteers, each of whom is assigned to 1 of 2 groups. Volunteers in group 1 are given the medication, and volunters in group 2 are given a placebo (a pill with no medication).
Which step is important in order to ensure scientifically valid results?
Correct Answer
A. Assigning the subjects to groups at random
Explanation
Assigning the subjects to groups at random is important in order to ensure scientifically valid results because it helps to eliminate any potential bias or confounding variables that could affect the outcome of the study. Random assignment ensures that each participant has an equal chance of being assigned to either the medication group or the placebo group, which helps to control for any individual differences between the groups. This increases the internal validity of the study and allows for more accurate conclusions to be drawn about the effectiveness of the medication in helping people sleep.
13.
Edison studies the effects of temperature on starch digestion in a test tube. He adds 2 g of starch and 1 mL of enzyme suspension to a test tube and incubates it at 25oC for 20 min. To accurately test the effects of temperature, Edison should begin a second test with 2 g of starch in a test tube and continue with which set of conditions?
Correct Answer
B. 1 mL of enzyme suspension incubated at 37oC for 20 min
Explanation
To accurately test the effects of temperature on starch digestion, Edison should begin a second test with 2 g of starch in a test tube and continue with the set of conditions that differ only in temperature. This means that the enzyme suspension should be the same volume (1 mL) but incubated at a different temperature. Therefore, the correct set of conditions would be 1 mL of enzyme suspension incubated at 37oC for 20 min. This will allow Edison to compare the effects of different temperatures on starch digestion while keeping other variables constant.
14.
Sunee and Jamila grow 2 distinct strains of E. coli bacteria following appropriate lab procedures. In Experiment 1, they use a new culture of Strain X and a 30-day old culture of Strain Y. In Experiment 2, they use a new culture of Strain Y and a 30-day old culture of Strain X. Sunee and Jamila measure the number of bacterial colonies and record the data in these graphs.
What is the most accurate conclusion about the growth rate of the bacteria?
Correct Answer
C. The 30-day old culture grows faster regardless of the strain.
Explanation
The most accurate conclusion about the growth rate of the bacteria is that the 30-day old culture grows faster regardless of the strain. This can be inferred from the information given in the question, where the number of bacterial colonies is measured and recorded in graphs. The fact that the 30-day old culture consistently shows faster growth regardless of whether it is Strain X or Strain Y suggests that the age of the culture has a significant impact on the growth rate.
15.
A student wants to determine whether temperature affects the rate at which mold grows on bread. The student puts one piece of bread inside a Petri dish, closes the lid, and places the Petri dish in the refrigerator. Which treatment would be the best comparison for this experiment?
Correct Answer
D. Placing another piece of bread in a closed Petri dish on the countertop
Explanation
The best comparison for the experiment would be placing another piece of bread in a closed Petri dish on the countertop. This is because the student wants to determine if temperature affects the rate of mold growth, so it is important to have a control group that is exposed to the same conditions as the experimental group (the bread in the refrigerator). By placing the bread in a closed Petri dish on the countertop, the student can ensure that the only difference between the two groups is the temperature, allowing for a valid comparison of the results.