Case Study The USDA conducted a series of experiments to determine the effect of European Corn Borer (ECB) infestation on the yields of four different varieties of corn – Golden Crop and Super Crop, and their genetically modified derivatives GC- 110 and SC-113. The genetically modified organisms (GMO) were engineered to be insect-resistant. Each corn plant produces a single ear of corn, with the number of kernels per ear depending on growth conditions [Fig 1]. Many problems, including insect infestation [Fig 2], plant disease, extreme weather conditions, or poor soil conditions, can decrease kernel yield. For the purpose of the USDA investigation, yield is defined as the kernel weight per ear of corn. All corn plants in this study were grown under the same environmental conditions (ie, soil type, water amount and sunlight exposure); however, the level of ECB infestation was varied. The results of the investigation are given in Table 1.

Questions:

Question 1

Which of the following statements best expresses the scientific question addressed by the USDA investigation (see attached file)? [2 pt; L2; I. A.1]

How destructive is the ECB on four common corn varieties?

How effective are GMO corn varieties in reducing the loss of yield to ECB infestation?

What effect does GMO corn varieties have on the growth and development of ECB larvae?

Are GMO corn varieties more resistant to ECB infestation than non-modified corn varieties?

2 points

Question 2

In the USDA investigation, what were the independent variables? Select all that apply – partial credit is not awarded! [2 pt; L2; I. A.2]

The variety of corn plant used in the experiment.

The number of plants tested in each treatment.

The yield of kernels per ear of corn.

The level of ECB infestation.

2 points

Question 3

In the USDA investigation, what was the dependent variable? [2 pt; L2; I. A.2]

The level of ECB infestation.

The yield of kernels per ear of corn.

The number of plants tested in each treatment.

The type of soil and amounts of water and sunlight the plants received.

2 points

Question 4

In the USDA investigation, which of the following were controlled variables? Select all that apply – partial credit is not awarded! [2 pt; L2; I. A.2]

The type of soil in which the plants are grown.

The amount of water each plant received.

The yield of kernels per ear of corn.

The level of ECB infestation.

2 points

Question 5

In the USDA investigation, what was the negative control? [2 pt; L2; I. A.2]

Corn plants that were grown in the dark.

Corn plants that were not exposed to ECB infestation.

Corn plants that were grown with all-purpose plant food.

Corn plants that were genetically modified to prevent flowering.

2 points

Question 6

In the USDA investigation, what were the levels of treatment? [2 pt; L2; I. A.2]

amounts of sunlight and water provided to the plants

number of ears produced per plant

amount of food given to the plants

low and high ECB infestation