Unit 1 Target 8-experimental Design Quiz

In a controlled experiment, there should be one independent variable. This is because the purpose of a controlled experiment is to isolate and manipulate a single factor to observe its effects on the dependent variable. By controlling all other variables, the researcher can determine the specific impact of the independent variable on the outcome. Having more than one independent variable would make it difficult to determine which variable is responsible for any observed changes in the dependent variable.

In order to accurately determine the effect of the independent variable on the experimental group, it is important to keep all other factors constant or the same for both the experimental group and control group. This ensures that any differences observed between the two groups can be attributed solely to the independent variable and not to any other factors. By maintaining identical conditions, the researcher can isolate the impact of the independent variable and draw valid conclusions from the experiment.

The independent variable in the experiment is the temperature of the samples. This is because the students are investigating the effect temperature has on Daphnia's heartbeat. They are manipulating the temperature by observing the crustacean's heartbeat at different temperature levels. The number of heartbeats per second is the dependent variable, as it is the outcome that is being measured and observed in response to the changes in temperature. The type of microscope used and the number of Daphnia in the cultures are not mentioned as factors being manipulated or observed in this experiment.

The dependent variable in this experiment is the effectiveness of the cough syrup. This is because the effectiveness of the cough syrup is what is being measured and observed in response to the different types of cough syrup being tested. The other options provided, such as the type of cough syrup, the number of people taking each cough syrup, and the number of days people take each cough syrup, are not the variables being measured or observed in this experiment.

The control group in the experiment was the monkey kidney cells in Group 2. This is because the scientists did not inoculate these cells with samples of the Ebola virus, serving as a baseline comparison to observe the effects of the virus on the cells in Group 1. By not introducing the virus to the cells in Group 2, any changes observed in Group 1 can be attributed to the presence of the Ebola virus rather than other factors.

Based on Morgan's hypothesis that the activity of amylase is greater at 37°C than at 25°C, she prepares two tubes with the same amount of starch and enzyme suspension. To accurately test her hypothesis, Tube 2 should be incubated at 25°C for 20 minutes. By comparing the activity of amylase in Tube 1 (incubated at 37°C) and Tube 2 (incubated at 25°C), Morgan can determine if the enzyme's activity is indeed greater at 37°C as hypothesized.

Lydia conducted her investigation to answer the question of how the chemistry of the soil affects the color of hydrangea blossoms. She noticed that the hydrangeas in Container 1 had pink blossoms, while those in Container 2 had blue blossoms. Despite receiving the same amount of light and water, she discovered that the soil in Container 1 had a pH of 6.0, while the soil in Container 2 had a pH of 5.0. This suggests that the pH level of the soil plays a role in determining the color of the hydrangea blossoms.

The students will choose to place 5 identical cultures of Daphnia at different temperatures. This is because the objective of the experiment is to investigate the effect of temperature on Daphnia's heartbeat. By having 5 identical cultures at different temperatures, the students can compare the heartbeats per second at each temperature and determine the effect of temperature on Daphnia's heartbeat.

The best design for Aisha's experiment would be to have 40 plants of the sun variety and 40 plants of the shade variety, with each group being tested under blue, green, red, and yellow light. This design allows for a more comprehensive comparison between the sun and shade varieties, as well as the different wavelengths of light. By having a larger sample size and testing each variety under different light conditions, Aisha can gather more reliable data and draw more accurate conclusions about the preferences of each variety for different wavelengths of light.

Scientific experimentation can most likely answer the question of what is the relationship between beak size and the number of offspring a bird produces. By conducting experiments and collecting data on birds with different beak sizes and their reproductive success, scientists can determine if there is a correlation between beak size and the number of offspring produced. This type of experimentation can help understand the evolutionary adaptations of birds and how beak size may impact their reproductive fitness.