Dr. Thistle wanted to test Dr. Garnet’s experiment but could only access a single tree with emerald ash borer infestation. Dr. Thistle injects the tree with the insecticide and then determines the percent of larvae killed. Dr. Thistle then reintroduces the emerald ash borer to the tree and repeats the experiment 49 more times. Is this experimental design valid? 

Stridor is a harsh, high-pitched breath sound heard during inhalation, caused by a blockage or narrowing of the upper airway.

What symptom does OPQRST help a rescuer to assess?

An upright position in which the patient leans forward onto 2 arms stretched outward and thrusts head and chin forward is known as:

(Use the following information for the next two questions) The emerald ash borer is considered one of the most destructive invasive species for trees in North America, specifically targeting ash trees. Most of the damage comes from the larvae which bore inside the tree for nutrients while disrupting the tree’s nutrition and water transport systems, ultimately leading to the tree’s death. Dr. Garnet wants to test whether a new injectable insecticide is effective against the emerald ash borer larvae. This insecticide prevents the larvae from feeding, ultimately leading to their starvation. To test the insecticide, Dr. Garnet finds a forest plot containing 50 infected ash trees. Dr. Garnet injects 25 of the trees with the 100 mL of the new insecticide and the remaining 25 trees with 100 mL of a neutral aqueous solution (similar to saline for humans). Dr. Garnet then determines the percent of larvae killed by counting the total number of living and dead larvae in the sample of trees.Which of the following is the best scientific mechanistic hypothesis for Dr. Garnet’s study?

Which of the following is the dependent variable? Choose the best answer. 

How did the population of birds develop insulating feathers during an ice age rather than, say, becoming featherless and naked?

Cotton-topped tamarins are small primates with tufts of long white hair on their heads. While studying these creatures, you notice that males with longer hair get more opportunities to mate and father more offspring. To test the hypothesis that having longer hair is adaptive in these males, you should ________. (Choose the best answer)

Refer to the image. On the left, there is a set of graphs that show frequencies of different alleles for two traits in a population in the first generation (different bars represent different alleles). On the right are labeled graphs representing the frequencies of those alleles for the same traits in the second generation. Which of the sets of graphs demonstrate(s) evolution of tail size but not evolution of beak size?   

A 62-year-old woman presents with a 2-year history of knee pain; it has been getting worse. She reports the pain is bilateral, but it is worse on her left side. She describes the pain as deep and “achy”; it is located in the front and back of her knees. Her pain increases after long days on her feet, and it is somewhat relieved with over-the-counter pain relievers and rest. She denies other joint problems. The patient denies trauma to her knees. She has no known other chronic medical conditions, and she takes no regular medications. She has never had surgery. She works in food service for the local school district. On physical exam, her BMI is 42. The other vital signs are normal. Both knees exhibit crepitus and some decreased range of motion in flexion and extension. No erythema, edema, or warmth is noted in the joints. The remainder of her examination is normal.An X-ray is obtained, and it shows narrowed joint spaces and some subchondral sclerosis.   Which of the following conditions is the most likely diagnosis for this patient?