USABO Open Exam Questions And Answers Verified 100% Correct

USABO Open Exam Questions And Answers Verified 100% Correct Which of the following statements about alternation of generations in land plants is TRUE? A. The gametophyte produces haploid cells by meiosis. B. In nonvascular plants (Bryophyta), the gametophyte stage is dominant. C. The sporophyte produces diploid spores that later undergo meiosis. D. The gametophyte stage is diploid. E. (A) and (D) are BOTH true. - ANSWER -B. In nonvascular plants (Bryophyta), the gametophyte stage is dominant. Which of the following best describes the function of sporopollenin in green algae? A. It reduces the risk of desiccation in exposed zygotes. B. It facilitates recognition of other individuals of the same species. C. It augments the effectiveness of the chloroplasts. D. It digests invasive bacterial cells. E. It deters predation by herbivores. - ANSWER -A. It reduces the risk of desiccation in exposed zygotes. Place the following statements regarding photosynthesis in C4 plants in the correct order: I. ATP is used to convert pyruvate to phosphoenolpyruvate (PEP). II. Mesophyll cells export four-carbon products such as malate through plasmodesmata to the bundle-sheath cells. III. PEP carboxylase adds CO2 to PEP to produce oxaloacetate. IV. CO2 is used to produce G3P in the Calvin cycle. V. CO2 is released in cells that contain the protein rubisco, which binds it. A. II, V, IV, I, III B. V, II, III, IV, I C. I, III, V, II, IV D. I, III, II, V, IV E. I, V, III, II, IV - ANSWER -D. I, III, II, V, IV Many important foods are fruits. Which of the following is not a fruit or part of a fruit? A. Corn B. Jalapeño C. Rhubarb D. Squash E. Tomato - ANSWER -C. Rhubarb Which of the following is not formed from neural crest cells? A. Peripheral nerves B. Bones of the middle ear C. Parts of teeth D. Bones of the jaw E. Muscles of the face - ANSWER -E. Muscles of the face The lymphatic system is most involved in the absorption of nutrients from which of the following foods? A. Bacon B. Banana C. Lettuce D. Skim milk E. White bread - ANSWER -A. Bacon Beriberi, a disease characterized by tingling, poor coordination, and reduced blood circulation, can be avoided by consuming adequate amounts of which of the following? A. Zinc B. Thiamine C. Folic acid D. Magnesium E. Vitamin A - ANSWER -B. Thiamine Which of the following hormones is NOT secreted by the anterior pituitary gland? A. Prolactin B. Oxytocin C. Luteinizing hormone D. Thyroid-stimulating hormone E. Adrenocorticotropic hormone - ANSWER -B. Oxytocin Which gland is directly controlled by messages from nerves leading into it? A. Adrenal cortex B. Adrenal medulla C. Anterior pituitary D. Testes E. Ovaries - ANSWER -B. Adrenal medulla The binding affinity of hemoglobin to O2 in the bloodstream is greatest at relatively A. High pH and high CO2 concentration. B. High pH and low CO2 concentration. C. Low pH and high CO2 concentration. D. Low pH and low CO2 concentration. E. Low pH, and does not depend on CO2 concentration - ANSWER -B. High pH and low CO2 concentration. The 2011 Nobel Prize in Physiology was awarded to Bruce Beutler, Jules Hoffmann, and Ralph Steinman in part for their discovery of the Toll receptors in fruit flies. The Tolllike receptors (TLRs) are their equivalent in mammals. Which of the following statements regarding TLRs is FALSE? A. TLRs function in the adaptive immune system as signaling receptors. B. TLRs are found both on the plasma membrane of cells well as the inner surfaces of vesicles. C. Specific TLRs are capable of recognizing pathogen-associated molecular patterns (PAMPs) such as flagellin, double-stranded RNA, and lipopolysaccharide (LPS). D. Signaling of TLRs promotes phagocytosis of foreign material. E. ALL of the above are true - ANSWER -A. TLRs function in the adaptive immune system as signaling receptors. Which of the following is important for the coordinated rhythmic nature of heart contraction? A. Acetylcholine transmission between cardiac myocytes. B. Desmosomes between cardiac myocytes. C. Gap junctions between cardiac myocytes. D. Plasmodesmata between cardiac myocytes. E. Tight junctions between cardiac myocytes. - ANSWER -C. Gap junctions between cardiac myocytes.