23. Compared with a C₃ plant, a C₄ plant:
(A) carries out more photorespiration.
(B) has a lower photosynthetic efficiency.
(C) has more Rubisco.
(D) has a higher leaf nitrogen content.
(E) needs more ATP to fix CO₂.

19. A sorus is a:(A) group of sporangia on the upper side of a fern leaf.(B) group of sporangia on the underside of a fern leaf.(C) group of sporangia along the edge of a fern stem.(D) single sporangium on the underside of a fern leaf.(E) group of fern spores.

20. The mature female gametophyte is called a(n):(A) embryo sac.(B) nucellus.(C) megasporangium.(D) endosperm.(E) ovule.

21. Which of the following statements concerning primary meristems is FALSE?(A) An example is the suspensor.(B) An example is the procambium.(C) An example is the ground meristem.(D) They are formed during embryogenesis.(E) They are meristematic.

22. If a plant produces leaves that are oriented horizontally, which of the following might you expect to find ingreater abundance on the upper side relative to the lower side?(A) stomata.(B) cuticle.(C) spongy mesophyll.(D) epidermal cells.(E) veins.

24. Which of the following does NOT involve the use of tissue culture?(A) micropropagation.(B) clonal propagation.(C) protoplast fusion.(D) hyhroponics.(E) meristem culture.

25. In the process of stomatal closing, which of the following events occurs first?(A) Water moves out of guard cells.(B) Water moves into guard cells.(C) Guard cell turgor pressure decreases.(D) Guard cell solute concentration declines.(E) Guard cell water potential increases.

26. Which of the following is the order in which flower parts are attached to the receptacle, from lowest or highest?(A) Petals ＞ sepals ＞ stamens ＞ carpels.(B) Sepals ＞ petals ＞ stamens ＞ carpels.(C) Sepals ＞ stamens ＞ petals ＞ carpels.(D) Sepals ＞ petals ＞ carpels ＞ stamens.

27. To move sucrose molecules from leaves to roots, the sucrose molecules must enter sieve elements. This involves: (A) moving the molecules through plasmodesmata. (B) the use of ATP to pump sucrose molecules with their concentration gradient across the plasma membrane. (C) the use of ATP to pump sucrose molecules against their concentration gradient across the plasma membrane. (D) the pumping of sucrose molecules across the plasma membrane with their concentration gradient without the use of ATP. (E) the pumping of sucrose molecules across the plasma membrane against their concentration gradient without the use of ATP.

28. Which of the following is a phenolic compound with a structure similar to aspirin?(A) systemin.(B) florigen.(C) brassinosteroids.(D) salicylic acids.(E) jasmonic acid.

29. Which of the following events is NOT associated with seed germination?(A) imbibition.(B) activation of existing enzymes.(C) synthesis of new enzymes.(D) synthesis of food reserves.(E) initiation of cell division and cell enlargement.