29. Which one of the following is considered to be an important plant hormone that helps plants cope with environmental stresses?
(A) auxins
(B)prostaglandins
(C) ethylene
(D) abscisic acid
(E)cytokinins

25. Which structure is correctly paired with its tissue system? (A) root hair - vascular tissue (B)guard cell - vascular tissue (C) tracheid - vascular tissue (D) companion cell - ground tissue

26. In most plants, phloem transports _____ from the _____ (source) to the __________ (sink) in the late spring. (A) amino acids； root； mycorrhizae (B)sugars； leaf； apical meristem (C) proteins； root； leaf (D) sugars； woody stem； root

27. Phytochromes are   not   involved in _____. (A) shade avoidance (B)biological clocks (C) control of vernalization (D) gravitropism

28. Which of these is a major trend in land plant evolution? (A) the trend toward larger gametophytes (B)the trend toward a gametophyte-dominated life cycle (C) the trend toward a sporophyte-dominated life cycle (D) the trend toward smaller size

30. A plant has sluggish wound healing abilities as well as an inability to store significant food reserves. If you could enhance the growth of a tissue to improve these properties, which tissue would you enhance? (A) parenchyma of the stem cortex (B)root apical meristem (C) periderm (D) lateral meristem

31. Chemical cues that help guide a developing pollen tube toward an ovule are released by the _____.(A) antipodal cells (B)synergids (C) egg (D) central cell (E)sperm

32. In the logistic growth model of population growth, at what population size - in terms of the carrying capacity (K) - is the population increasing most rapidly? (A) K (B)K/2 (C) K/3 (D) K/4

33. What is the main reason leading to a uniform dispersion pattern among individuals within a population? (A) Competition (B)Mutualism (C) Resource availability (D) Environmental factors

34. When considering the average food chain, which of the following statements is true? (A) Secondary consumers are the most abundant organisms in an ecosystem. (B)The longer the food chain, the more stable the ecosystem. (C) Biomass decreases moving up the food chain. (D) The trophic level with the highest species abundance is usually the primary producers.

35. Which of the following statements is   not   true? (A) The risk of stroke can be reduced by avoiding the damage to endothelium of vessels. (B)Increased sympathetic activity raises blood pressure by increasing the strength and rate of the heartbeat. (C) The left ventricle pumps the same amount of blood as the right ventricle. (D) If action potential propagation through the bundle of His was blocked, the SA node would no longer set the pace for atrial contraction. (E)The velocity of blood flow in the veins is faster than that in the capillaries.