38. If a plant detects increased levels of light reflected from the leaves of encroaching neighbors, it typically responds with stem elongation, production of erect leaves, and reduced lateral branching. How do these responses help the plant compete?
(A) They allow the plant to store more water in its stems.
(B) They enhance the plant's ability to produce defensive chemicals.
(C) They enable the plant to grow taller and capture more light, reducing shading from competitors.
(D) They promote earlier flowering and seed production.

34. The ability of the mammalian kidney to produce urine that is much more concentrated than blood is primarily due to:(A) The active transport of water in the collecting duct.(B) The presence of a short loop of Henle in cortical nephrons.(C) The establishment and maintenance of a steep osmolarity gradient in the renal medulla by the loops of Henle of juxtamedullary nephrons.(D) The selective reabsorption of all solutes, including urea, in the proximal tubule.

35. What are the four main stages of food processing in animals, in order?(A) Digestion, ingestion, absorption, elimination(B) Ingestion, digestion, absorption, elimination(C) Ingestion, absorption, digestion, elimination(D) Digestion, absorption, ingestion, elimination

36. Given that sponges lack true tissues and organs, how do they accomplish vital functions such as gas exchange, nutrient transport, and waste disposal?(A) They possess a gastrovascular cavity that handles all internal transport.(B) Through specialized, but rudimentary, circulatory and excretory systems.(C) By simple diffusion across the surfaces of their cells, which are in direct contact with the water environment.(D) They rely on symbiotic bacteria to perform these functions for them.

37. In a closed circulatory system, where does chemical exchange occur between the blood and interstitial fluid?(A) Arteries (B) Veins (C) Capillaries (D) Ventricles

39. Which type of immunity is active immediately upon exposure to a pathogen and is the same whether or not the pathogen has been encountered previously?(A) Adaptive immunity (B) Acquired immunity(C) Innate immunity (D) Humoral immunity

40. If a complete ring of bark is removed from around a tree trunk (a technique called girdling), the tree will die, but typically slowly (in weeks) rather than quickly (in days). Which of the following best explains this observed timeframe?(A) Girdling only disrupts the xylem, and the tree's roots can store enough water to survive for a few days.(B) Girdling severs the phloem, cutting off sugar transport to the roots, which leads to root starvation and eventual death, a process that takes weeks.(C) Girdling directly kills all the living cells in the trunk, but the leaves can continue photosynthesis until stored carbohydrates are depleted.(D) The tree can regenerate the phloem within days, thus preventing rapid death, but the energy cost is high.

41. Which type of plant supplements its mineral nutrition by digesting animals?(A) Epiphytes (B) Parasitic plants(C) Carnivorous plants (D) Nitrogen-fixing plants

42. In mammalian circulation, oxygen-rich blood returns from the lungs to the heart via the:(A) Pulmonary arteries (B) Aorta (C) Venae cavae (D) Pulmonary veins

43. A plant has a double mutation: ctr (constitutive triple response, meaning it always shows the triple response regardless of ethylene) and ein (ethylene insensitive, meaning it cannot respond to ethylene). What would be its triple-response phenotype?(A) It would display a normal triple response, as the mutations compensate for each other.(B) It would not display the triple response, as the ein mutation makes it insensitive to ethylene.(C) It would constitutively display the triple response, because the ctr mutation is dominant.(D) Its phenotype would be intermediate between a wild-type plant and a ctr mutant.

44. If a human female begins taking estradiol and progesterone immediately after the start of a new menstrual cycle, how will ovulation be affected?(A) Ovulation will be stimulated early in the cycle.(B) Ovulation will be delayed or inhibited.(C) Ovulation will occur normally, but fertilization will be prevented.(D) Ovulation will become irregular, but not necessarily inhibited.