12. In guard cells, _____ is the dominant osmoticum in the morning, and  _____ is the dominant osmoticum in the afternoon.
(A) Cl-； sucrose.
(B) malate； K+.
(C) K+； malate.
(D) sucrose； K+.
(E) K+； sucrose.

8. Which of the following statements about sources and sinks in assimilate movement is FALSE? (A) a plant part unable to meet its nutritional needs functions as a sink. (B) in seedlings, the cotyledons commonly act as the major sinks. (C) in mature plants, the upper leaves commonly act as sources for the shoot apex. (D) in mature plants, the lower leaves commonly act as sources for the roots. (E) developing fruits are highly competitive sinks.

9. Which of the following indicates the correct sequence of tissues through which water moves from the soil into the root? (A) root hairs, endodermis, exodermis, cortical cells, vascular cylinder. (B) root hairs, endodermis, cortical cells, vascular cylinder, exodermis. (C) exodermis, endodermis, epidermis, vascular cylinder, cortical cells. (D) epidermis, exodermis, cortical cells, endodermis, vascular cylinder. (E) epidermis, endodermis, exodermis, cortical cells, vascular cylinder.

10. Which of the following statements is NOT consistent with the cohesion-tension theory? (A) a gradient of water potential exists between the stem and the root. (B) transpiration brings about a lowered water potential in the leaves. (C) water in the xylem is under tension. (D) a gradient of water potential provides the driving force for water movement. (E) root pressure is essential to the movement of water from roots to leaves.

11. Plant hormonal regulation differs from animal hormonal regulation in that _____. (A) there are no dedicated hormone-producing organs in plants while endocrine glands produce hormones in animals. (B) the transport of plant hormones is local and limited. (C) plants do not have feedback mechanisms like animals. (D) only animal hormone concentrations are developmentally regulated. (E) only animal hormones have either external or internal receptors.

13. In the secondary growth of a tree, the periderm consists of: (A) phellem only. (B) phellogen only. (C) phelloderm only. (D) phellem and phellogen only. (E) phellem and phellogen, and phelloderm.

14. Which of the following features is unique to Angiosperms that helps them to become the most successful terrestrial plants? (A) wind pollination. (B) dominant gametophytes. (C) fruits enclosing seeds. (D) embryos enclosed within seed coats. (E) the secondary growth.

15. The endosperm is a major part of monocot seed. In most eudicots, _____ (A) there is also a substantial amount of the endosperm. (B) the endosperm never starts to form after double fertilization. (C) the endosperm nutrients are repackaged into the cotyledons. (D) the endosperm replaces cotyledons during seed development. (E) both the endosperm and cotyledons exist together at seed maturity.

16. In land plants, matrotrophy refers to the: (A) attraction of sperm by the egg. (B) nourishment of the zygote by the archegonium. (C) transport of sugars through the placenta. (D) division of the zygote within the venter. (E) movement of sugars through plasmodesmata.

17. In ferns, the formation of antheridia in gametophytes is induced by: (A) antheridiogens. (B) antheridiophores. (C) androecium. (D) cytokinins. (E) auxin.

18. Embryophytes are characterized by having: (A) few mitotic divisions between fertilization and meiosis. (B) a multicellular embryo that has stomata. (C) a multicellular, matrotrophic embryo. (D) a dominant gametophyte generation. (E) vascular tissues.