14. The best reason antibiotics do not treat the flu is that the flu is caused by:

R9 (Scientific reasoning)An ad says: ‘In a clinical trial, symptoms improved by 30%.’ The ad does not state what happened in the placebo group. Why does that matter?

21. Which nutrient is the body’s primary quick source of energy?

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?