73) What is thought to be the correct sequence of the following events during the Carboniferous
period?
1. Vascular plants become more prevalent.
2. Megaphylls with large surface areas become more prevalent.
3. Atmospheric CO2 levels decline dramatically.
4. Global cooling occurs, leading to widespread glaciations.
A) 1, 2 ,3, 4
B) 2, 1, 3, 4
C) 2, 1, 4, 3
D) 1, 2, 4, 3
E) 3, 4, 1, 2
74) The fruit of the mistletoe, a parasitic angiosperm, is a one-seeded berry. In members of the
genus Viscum, the outside of the seed is viscous (sticky), which permits the seed to adhere to
surfaces, such as the branches of host plants or the beaks of birds. What should be expected of
the fruit if the viscosity of Viscum seeds is primarily an adaptation for dispersal rather than an
adaptation for infecting host plant tissues?
A) It should be drab in color.
B) It should be colored so as to provide it with camouflage.
C) It should be nutritious.
D) It should secrete enzymes that can digest bark.
75) What is the greatest threat to plant diversity?
A) insects
B) grazing and browsing by animals
C) pathogenic fungi
D) competition with other plants
E) human population growth