Question

Diversification in plant life appeared

(a) due to long periods of evolutionary changes

(b) due to abrupt mutations

(c) suddenly on earth

(d) by seed dispersal.

Answer and Explanation:

84. (a): Diversification in plant life appeared due to long periods of evolutionary changes. Initially plants were thalloid. There were no differentiation among root, stem and leaves. Vascular tissues were absent.

Answer 1

(a) due to long periods of evolutionary changes

The first land plants appears in the Ordovician period around 450 million years ago then it began to diversify around 430 million years ago, in the  Late Silurian period.

Bryophytes (Thalloid no vascular tissue) → Pteridophytes (Differentiation in vascular tissue begins) → Gymnosperms (no fruit formation) → Angiosperms (fruit present), this is the evolutionary changes sequence .