Can you determine which instances reflect a valid experiment or conclusion? Check only those that are valid.

a. A biology class is conducting an experiment to determine how soil pH affects the germination of pine seedlings. 30 pine seeds are placed in pots of soil with varying pH levels: 4.5, 6.5, 7.0, 7.5, 8.5, and 9.0. Pot size, water, and light exposure were constant for all pots.

b. A marine biologist is examining the effects of oil pollution on a population of seagulls (Larus canus). He is particularly interested in determining whether oil pollution reduces the number of eggs that may be hatched in each seagull nest. During one breeding season, he has counted the number of eggs present in 16 seagull nests and recorded the distance from each nest to a nearby oil refinery

c. After months of grueling research drinking many, many colas, Karl has come to the conclusion that Brand A cola tastes better than Brand B cola.

d. Jeanette was conducting an experiment to determine if plants grow better when exposed to rap music. She bought two identical plants and exposed one to rap music for two weeks while the other grew without music. From the data, Jeanette determined that plants do not grow better with rap music.

e. Robert is instructed in a lab experiment to first record the ambient temperature of the room. To do this, he holds the thermometer under a bright light to accurately read it. He then reads and records the data as 33°C.

Quality of any experiment depends upon two things reliability and validity. Reliability is measure of regeneration of results every time an experiment is performed under specific conditions.

Validity is measure of accuracy of results of an experiment. It can be check by two ways: internal validity (checks the design of the experiment) and external validity (checks if the conclusion is the real explanation of the phenomenon).

Now, in marine biologist experiment, he concluded the results only after one breeding season. This makes his results unreliable as it might have happened by chance.

Similarly, in cola experiment the taste was only checked by one candidate i.e. Karl. He might have problem in his taste buds. In addition, the temperature of cola can also affects its taste which is not taken care of in the experiment. Hence, it is not the valid experiment.

Similarly. Jeanette could use more plants for her experiment and Robert just followed only one instruction. He didn't perform any experiment.