One of the differences between the outer wall and the inner wall of pollen is that the outer wall contains the following substances:
A: protein
B: cellulose
C: sporopollenin
D: protein and sporopollenin
A: protein
B: cellulose
C: sporopollenin
D: protein and sporopollenin
举一反三
- The wall of pollen grain is divided into two layers. A: primary wall and secondary wall B: pectin layer and primary wall C: outer wall and inner wall D: pectin layer and secondary wall
- Between the outside wall of glass and the two inside walls of glass, there is ______. A: an empty space B: another huge wall C: a triple-glazed wall
- The festoon gate _____(act) as a divider between the outer and innercourtyards, the outer house and the inner house.
- 6.The festoon gate acts_____a divider between the outer and innercourtyards, the outer house and the inner house. A: to B: In C: as
- Be careful! ________. A: The wall is falling B: The wall is to fall C: he wall will fall D: The wall is going to fall