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 seedlings 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 are the pine seedlings and the treatments are the various light levels provided, namely full light, 25% light, and 5% light.

Step-by-step explanation:

The experimental units in the study you're referring to are the pine seedlings, as they are the primary subjects being observed for effects during the experiments. The treatments, on the other hand, involve different light levels that the seedlings are exposed to, which are full light, light reduced to 25% of normal by a shade cloth, and light reduced to 5% of normal. Thus, from the options provided, the answer to your question is: E) Experimental units: pine seedlings; Treatments: full light, 25% light and 5% light.