65. If water is abundant, a plant's guard cells will____ and the stomata will_____.
(A) swell； close；
(B) collapse； open；
(C) swell； open；
(D) collapse； close.

61. A gaseous hormone produced by plants that helps control fruit ripening is__? (A) dextrose；(B) carbon dioxide；(C) chlorophyll；(D) ethylene.

62. If a plant exhibits determinate growth, the plant__? (A) produces auxiliary roots to help stabilize the plant；(B) produces seeds only at one time during its life；(C) continues to grow until the environment determines that it cannot；(D) stops growing when the plant reaches its mature size.

63. The _____ transports water and dissolved minerals from the roots of the plant to the shoots of the plant. (A) stomata；(B) epidermis；(C) guard cells；(D) xylem.

64. The _____ and _____ of a plant's leaf help conserve water in a plant. (A) root hairs； stomata； (B) Casparian strip； cuticle；(C) Casparian strip； endodermis；(D) stomata； cuticle.

66. The whorl of a flower that consists of all the sepals is the__? (A) stamen；(B) calyx；(C) carpel；(D) corolla.

67. The plant hormone that stimulates cell division in seeds and fruits is__? (A) auxin；(B) cytokinin；(C) abscisic acid；(D) ethylene.

68. In biology lab, your teacher places petri dishes on the lab table. Upon examination, you observe that there are lumps of plant tissue, and you are told that they have been grown artificially and can produce new plants. Each lump is a(n)__ (A) tetraploid zygote；(B) stigma；(C) amnion； (D) callus.

69. Which phrase defines smooth muscle? (A) used for slow, involuntary movements；(B) used to move bones；(C) beats the heart；(D) shows striations.

70. The systems that coordinate communication are__? (A) skeletal and muscular；(B) circulatory and respiratory；(C) nervous and endocrine；(D) digestive and circulatory.

71. Which of the following best describes how a neuron fires? (A) Na+ ions cross the plasma membrane, initiating a wave that travels down the axon；(B) Vesicles carry neurotransmitters from the nucleus to the other end of the neuron；(C) Na+ ions enter one end of the neuron and diffuse to the other end, down the axon；(D) Neurotransmitters enter one end of the neuron and diffuse to the other end, down the axon.