Question

which statement represents a valid conclusion based on information in the graph?
1 there was a decrease in the amount of phosphorus dumped at site 2 from 1991 to 1997.
2 pollution controls may have been put into effect at site 1 starting in 1995.
3 there was most likely no vegetation present near site 2 from 1993 to 1994.
4 there was a greater variation in phosphorus concentration at site 1 than at site 2.

1. the concentration of salt in water affects the hatching of brine shrimp eggs. brine shrimp eggs will develop and hatch at room temperature in glass containers of salt solution. describe a controlled experiment having three separate experimental groups that could be used to determine the best concentration of salt solution in which to hatch brine shrimp eggs. your answer must include:

1 • a description of how the control group and each of the three experimental groups will be different
2 • two conditions that must be kept constant in the control group and the experimental groups
3 • what data that should be collected, and how often
4 • one sample of experimental results that would indicate the best concentration of salt solution in which to hatch brine shrimp eggs.

1. a student hypothesized that lettuce seeds would not sprout (germinate) unless they were placed in the dark. the student planted 10 lettuce seeds in soil that was kept in the dark and planted another 10 lettuce seeds in soil that was exposed to light. the data collected are shown in the following table.

one way to improve the reliability of these results would be to
1 conclude that darkness is necessary for lettuce seed germination
2 conclude that light is necessary for lettuce seed germination
3 revise the hypothesis
4 repeat the experiment

1. to determine which colors of light are best used by plants for photosynthesis, three types of underwater plants of similar mass were subjected to the same intensity of light of different colors for the same period of time. all other environmental conditions were kept the same. after 15 minutes of exposure to light, a video camera was used to record the number of gas bubbles each plant gave off (due to photosynthesis) in a 30 - second time period. each type of plant was tested six times. the average of the data for each plant type is shown in the table below.

average number of bubbles given off in 30 seconds
plant type red light yellow light green light blue light
elodea 35 11 5 47
potamogeton 18 8 2 63
unouarta 28 9 6 39

which statement is a valid conclusion based on the data?
1 each plant carried on photosynthesis best in a different color of light
2 red light is better for carrying on photosynthesis than blue light is.
3 each plant carried on photosynthesis best in red light and in blue light.
4 water probably filters out the red light and the green light.

1. a certain plant that usually grows in slightly basic soil produces flowers with white petals. sometimes the same plant species produces flowers with red petals. a company that sells the plant wants to know if soil ph affects the color of the petals in this plant. design a controlled experiment to determine if soil ph affects petal color. in your experimental design be sure to

Explanation:

Step1: Analyze question 27

Examine the graph about phosphorus - dumping at two sites.

Step2: Evaluate option 1

From 1991 - 1997 at Site 2, the amount of phosphorus did not always decrease, so this is incorrect.

Step3: Evaluate option 2

In 1995 at Site 1, the phosphorus level starts to change, indicating possible pollution - control implementation, so this is correct.

Step4: Evaluate option 3

There is no evidence in the graph to support the lack of vegetation near Site 2 from 1993 - 1994, so this is incorrect.

Step5: Evaluate option 4

The graph shows less variation in phosphorus concentration at Site 1 than at Site 2, so this is incorrect.

Step1: Analyze question 28

We need to design a controlled experiment for brine - shrimp egg hatching.

Step2: Define control and experimental groups

The control group has a standard salt - solution concentration. Experimental groups have different salt - solution concentrations.

Step3: Identify constant conditions

Room temperature and number of eggs should be kept constant.

Step4: Determine data collection

Count the number of hatched eggs at regular intervals.

Step5: Provide sample result

If the group with 3% salt - solution has the most hatched eggs, it may be the best concentration.

Step1: Analyze question 29

The student is testing the hypothesis about lettuce - seed germination in light and dark.

Step2: Analyze data

The data does not strongly support the hypothesis that darkness is necessary for germination. To improve reliability, repeating the experiment is a good approach.

Step1: Analyze question 30

We are looking at the effect of different colored lights on plant photosynthesis.

Step2: Evaluate option 1

Each plant has a different best - performing light color, so this is correct.

Step3: Evaluate option 2

Blue light is better than red light for some plants, so this is incorrect.

Step4: Evaluate option 3

Not all plants perform best in red and blue light, so this is incorrect.

Step5: Evaluate option 4

There is no evidence in the data about water filtering light, so this is incorrect.

Answer:

1. Pollution controls may have been put into effect at Site 1 starting in 1995.