Scenario E: Carrier screening and test interpretationA PCR-based screening test has sensitivity 98% and specificity 99%. In this region, 4% of people are carriers. Assume 1,000 people are tested. Expected outcomes: True carriers: 40 -> true positives 39; false negatives 1 True non-carriers: 960 -> true negatives 950; false positives 10E6. Reasonable next step after a positive screening result:

Scenario B: Indoor farm lighting scheduleAn indoor farm tested a new lighting schedule for lettuce for 4 weeks. Standard: steady light for 16 h/day. Pulsed: 10 min on / 5 min dim for 16 h/day. During week 3, CO2 levels were higher in the pulsed room due to ventilation issues. Data (n=20 each): Standard: final mass 320 g; water 14.0 L; CO2 week 3 = 420 ppm Pulsed: final mass 350 g; water 13.0 L; CO2 week 3 = 520 ppmB5. Best graph choice to compare final mass between two groups:

19. Most traits (like height) are influenced by:

Scenario F: Insecticide resistance over timeA property management company used the same insecticide monthly for four years. Each year they measured percent surviving a standard dose and the frequency of a resistance allele (R). Year 1: survival 5%; R = 0.06 Year 2: survival 18%; R = 0.20 Year 3: survival 42%; R = 0.45 Year 4: survival 70%; R = 0.72F4. Which action would most likely slow resistance development?

Scenario A: Start-time pilot and student outcomesA district piloted a later start time at one high school for one grading period. Central shifted from 7:20 AM to 8:05 AM. North stayed at 7:20 AM. Central also launched a new after-school tutoring program during the same period; North did not. Data (averages): Central before: sleep 6.4 h; tardies 18 per 100; exam 78% Central after: sleep 7.1 h; tardies 11 per 100; exam 80% North before: sleep 6.5 h; tardies 17 per 100; exam 79% North after: sleep 6.6 h; tardies 16 per 100; exam 79%A5. Which would best strengthen validity for a conclusion about start time?

Scenario B: Indoor farm lighting scheduleAn indoor farm tested a new lighting schedule for lettuce for 4 weeks. Standard: steady light for 16 h/day. Pulsed: 10 min on / 5 min dim for 16 h/day. During week 3, CO2 levels were higher in the pulsed room due to ventilation issues. Data (n=20 each): Standard: final mass 320 g; water 14.0 L; CO2 week 3 = 420 ppm Pulsed: final mass 350 g; water 13.0 L; CO2 week 3 = 520 ppmB2. The CO2 difference is most likely a:

Evaluate the following claim and answer the question based on your understanding of biological concepts we’ve covered so far. This tea flushes toxins. Which response is most scientifically grounded?

R6 (Scientific reasoning)A skincare brand says its cream ‘rebuilds collagen in 24 hours.’ Their study measured skin hydration and found it increased. What is the key problem?

Evaluate the following claim and answer the question based on your understanding of biological concepts we’ve covered so far. If a condition runs in families, it must be genetic. What is the best correction?

C18 (Cells and energy)Select all that apply. Which are reasonable indicators a cell is under stress from lack of oxygen?