Question

The ability to grow in shade may help pine trees found in the dry forests of Arizona to resist drought. How well do these pines grow in shade? Investigators planted pine scelings in a greenhouse in either full light, light reduced to 25% of normal by shade cloth, or light reduced to 5% of normal. At the end of the study, they dried the young trees and weighed them.

What are the experimental units and the treatments?

A)Experimental units: pine seedlings
Treatments: light levels

B) Experimental units: greenhouses
Treatments: light levels

C)Experimental units: Investigators
Treatments: full light, 25% light and 5% light

D) Experimental units: pine seedlings
Treatments: weight of the trees

E)Experimental units: pine seedlings
Treatments: full light, 25% light and 5% light

Answer 1

The experimental units in this study are the pine seedlings, and the treatments are the different light levels of full light, 25% light, and 5% light. These treatments aim to investigate the effect of light availability on the growth of the pine seedlings.

The correct answer to the given question is option E).

The experimental units and the treatments in this study of pine seedlings growth in relation to light levels are an important aspect of the design of the experiment. The experimental units refer to the individual entities or objects that are being manipulated or measured in the experiment. In this case, the experimental units are the pine seedlings themselves. Each seedling acts as an individual unit that receives a particular treatment.

The treatments are the different conditions applied to the experimental units. Here, the treatments are the various light levels that the pine seedlings were exposed to: full light, light reduced to 25% of normal, and light reduced to 5% of normal. These distinct light environments are expected to affect the growth of the pine seedlings, which was measured at the conclusion of the study by drying and weighing the trees.

So, the correct answer identifying the experimental units and treatments in the study is:

E) Experimental units: pine seedlings

Treatments: full light, 25% light, and 5% light