Planning Time------10 minutes
Writing Time------80 minutes
Directions: Questions 1 and 2 are long free-response questions that require about 22 minutes each to answer and are worth 10 points each. Questions 3–8 are short free-response questions that require about 6 minutes each to answer. Questions 3–5 are worth 4 points each and questions 6–8 are worth 3 points each.
Read each question carefully and completely. Write your response in the space provided for each question. Only material written in the space provided will be scored. Answers must be written out in paragraph form. Outlines, bulleted lists, or diagrams alone are not acceptable.
1.Many species have circadian rhythms that exhibit an approximately 24-hour cycle. Circadian rhythms arecontrolled by both genetics and environmental conditions, including light.
Researchers investigated the effect of light on mouse behavior by using a running wheel with a motion sensor torecord activity on actograms, as shown in Figure 1.
Figure 1. Strategy for recording mouse activity data. When a mouse is active on the running wheel, the activity is recorded as a dark horizontal line on an actogram. When the mouse is inactive, no dark line is recorded.
For the investigation, adult male mice were individually housed in cages in a soundproof room at 25°C Each mouse was provided with adequate food, water, bedding material, and a running wheel. The mice were exposed to daily periods of 12 hours of light (L) and 12 hours of dark (D)(L12:D12) for 14 days, and their activity was continuously monitored. The activity data are shown in Figure 2.
Figure 2. Actogram of mouse activity under L12:D12 conditions. Each row represents a 24-hour period, and the dark horizontal lines represent activity on the running wheel.
After 14 days in L12:D12, the mice were placed in continuous darkness (DD), and their activity on the running wheel was recorded as before. The activity data under DD conditions are shown in Figure 3.
Figure 3. Actogram of mouse activity under DD conditions. Each row represents a 24-hour period, and the dark horizontal lines represent activity on the running wheel.