20. Mycorrhizae enhance plant nutrition mainly by
(A) absorbing water and minerals through the fungal hyphae
(B) providing sugar to root cells, which have no chloroplasts
(C) converting atmospheric nitrogen to ammonia
(D) enabling the roots to parasitize neighboring plants.

16. Which of the following respiratory systems is not closely associated with a blood supply? (A) the tracheal system of an insect (B) the skin of an earthworm (C) the gills of fishes (D) the skin of an amphibian (E) the lungs of a vertebrate

17. In a living organism, cells die either through apoptosis (programmed cell death) or necrosis (cells swell and burst). Which the following statement is false? (A) apoptosis is induced in immature T-cells that recognize self-antigens (B) intestinal epithelial cells losing contact with the basal lamina undergo apoptosis (C) neural stem cells undergoing apoptosis expose on their surface a signal promoting phagocytosis (D) Necrosis never induces an inflammatory immune response (E) Cytochrome C is involved in intracellular apoptotic cascade

18. The effect of various mutations in a gene x coding for a protein X, essential for the synthesis of leucine, is studied in a haploid yeast. The beginning and the end of the complete sequence of the coding strand of x is given below. Indicate the following statement is true. (A) Cells with a CT mutation at position 13 produce shorter mRNA of x (B) Cells with a AT mutation at position 37 produce shorter version of X (C) Cells with a AT mutation at position 16 are able to grow on a medium lacking leucine. (D) Cells with an additional G between positions 33 and 34 produce functional X.

19. The high osmolarity of the renal medulla is maintained by all the following except (A) active transport of salt from the upper region of the ascending limb (B) the spatial arrangement of juxtamedullary nephrons (C) diffusion of urea from the collecting duct (D) diffusion of salt from the descending limb of the loop of Henle. 

沒有 【段考】高三生物 權限，請先開通．

沒有 【段考】高三生物 權限，請先開通．

沒有 【段考】高三生物 權限，請先開通．

沒有 【段考】高三生物 權限，請先開通．

沒有 【段考】高三生物 權限，請先開通．

沒有 【段考】高三生物 權限，請先開通．