Question

Which of the following is not a characteristic that distinguishes gymnosperms and angiosperms from other plants?

(A) dependent gametophytes

(B) ovules

(C) pollen

(D) alternation of generations

Short answer

(A) The option “dependent gametophytes” isfalse.

(B) The option “ovules” isfalse.

(C) The option “pollens” isfalse.

(D) The option “alternation of generations” is true.

Step-by-step solution

Diversity of Kingdom Plantae

The Kingdom Plantae comprises photosynthetic members of different structural organizations. Some groups lack proper tissues for water conduction, while some have specialized tissues for conducting water and nutrients. Some are categorized as non-seed plants, while some plants are classified as seed plants.

Explanation of option ‘(A)’

The plants under angiosperms and gymnosperm groups are considered to be the most evolved. The sporophytic body structure dominates the life cycle and is photosynthetically active.

On the other hand, gametophytic structures are not photosynthetic. This means gametophytes are dependent on sporophytic bodies for food.

Thus, the dependence of gametophytes on sporophytic generation is only found in angiosperms and gymnosperms.

Therefore, the given option is false.

Explanation of option ‘(B)’

Ovules are the cells that contain the female gametic cell (egg cells) and are only found in the seed plants (angiosperms and gymnosperms). The non-seed plants lack the development of ovules, and so it is another distinguishing characteristic of seed plants.

Thus, the egg cells containing ovules are only present in female gametophytes of seed plants.

Therefore, the given option is false.

Explanation of option ‘(C)’

The seed plants, that is, the angiosperm and gymnosperm plants, exhibit heterospory by forming distinguishable male and female gametes. The male gametic cells are produced by microgametophytes which are stored within pollens.

Thus, pollens are only present in members of gymnosperms and angiosperms.

Therefore, the given option is false.

Explanation of option ‘(D)’

The life cycle exhibited by different eukaryotic kingdoms can be of different types; in the Kingdom Plantae, every member undergoes a single life cycle, which is an alternation of generation. In this life cycle, a multicellular body is observed in both sporophytic and gametophytic structures.

Thus, the alternation of generation is exhibited by all plants and is not a distinguishing character.

Therefore, the given option is true.