Chapter 21, Problem 1SA

The first plants were_________.

a. ferns	c. bryophytes
b. flowering plants	d. conifers

Summary Introduction

Introduction:

Plants are eukaryotic, multicellular and photosynthetic organism on Earth. The plants evolved 450 million years ago from a group of freshwater alga. These contain chlorophyll, which helps in the process of photosynthesis.

Answer to Problem 1SA

Correct answer:

The first plants were bryophytes. Hence, the correct answer is option c.

Explanation of Solution

Reason for correct answer:

Option c. is given as, “bryophytes.”

Bryophytes are called first plants because they are capable of surviving in water as well as on land. They are commonly known as nonvascular plants. Bryophytes are categorized into three lineages: liverworts, mosses, and hornworts. They have internal conducting vessels. They obtain nutrients from the surface. They have a better capability to survive in unfavorable conditions such as drought. The vascular plants such as ferns and conifers have evolved from bryophytes.

Reason for incorrect answer:

Option a. is given as, “ferns.”

Ferns are called seedless vascular plants. They release spores into the environment that develop into a gametophyte. Ferns have fronds (leaves) and a horizontal underground stem. Hence, option a. is incorrect.

Option b. is given as, “flowering plants.”

Angiosperms are called flowering plants because these are the only plants that can make flowers and fruits. These have leaves, sepals, and petals. These are considered as the most evolved group of plants. Hence, option b. is incorrect.

Option d. is given as, “conifers.”

Conifers are included in the class of gymnosperms. These include various species of shrubs and trees. These can tolerate drought conditions as well as cold conditions. Conifers generally have naked seeds. Hence, option d. is incorrect.

Hence, the options a., b., and d. are incorrect.

Conclusion

Bryophytes were characterized by vessels and flagellated sperms. They do not have seeds, leaves, and stem. It is the reason bryophytes are considered as first plants. Thus, the correct option is c.