Question

When you examine the life cycle of land plants starting with nonvascular seedless plants and ending with the seeded, vascular plants. What is one main change that you notice?
a. the sporophyte stage becomes the dominant stage
b. the gametophyte stage becomes the dominant stage
c. the haploid stage becomes the dominant stage
d. the sporophyte stage becomes microscopic

Answer 1

Answer:

a. the sporophyte stage becomes the dominant stage

Explanation:

Non vascular seedless plants are represented by bryophytes (mosses, liverworts and hornworts). Within their life cycle, gametophyte is the dominant stage as it the assumes the nutritional role (photosynthetic activity) and lives longer than the sporophyte, which grows on and at expense of the gametophyte. Sporophytes are usually non photosynthetic and with a shorter lifetime, only reduced to a foot, stalk and capsule where spores are developed and then released.

On the other hand, in seeded, vascular plants (conifers and flowering plants) the situation is quite the opposite, as the sporophyte is the dominant stage for it is macrocopically much more evident and larger, its lifetime accounts for almost the total life cycle and assumes all the photosynthetic role (proving nutrients to the gametophyte). In these plants the gametophyte is completely dependent on the sporophyte and is reduced to a the pollen grain (male gametophyte or micro gametophyte) or embryo sac (female gametophyte or mega gametophyte).