Chapter 21, Problem 30A

Summary Introduction

Introduction :

The vascular seed plant comprises over 250000 vascular plants. Development of seed habit made the seed plants independent of the requirement of external sources of water at the time of fertilization. Vascular seed plants produce seeds. Each seed generally contains a tiny sporophytes surrounded or covered by protective tissue. Seeds have one or more cotyledons. Cotyledons are the structures that either store food or help absorb food for the tiny sporophyte.

Answer to Problem 30A

Correct answer :

The correct answer is option (C) Coniferophyta.

Explanation of Solution

Explanation/justification for the correct answer :

Option (C) Coniferophyta. Conifers vary in size from low-growing shrubs that are few centimeters tall to massive towering trees about 50 m tall. The leaves of conifers are needle-like or scaly. Conifers exhibit adaptations to their environments. Most conifers have drooping branches and many conifers grow in snowy climates. They have wax-like coating that covers their leaves and reduces water loss. So, the correct answer is option (C).

Explanation for incorrect answer :

Option (A) Gnetophyta. Gnetophyta can live for as long as 1500-2000 years. There are only three genera of gnetophytes, each exhibiting unique structural adaptations to its climate. Welwitschia has a large storage root and two continuously growing leaves that eventually can exceed 6 m in length. So, this is an incorrect option.

Option (B) Anthophyta. Anthophytes are the most widely distributed plants due to adaptations that allow them to develop in terrestrial and aquatic habitats. About 75 percent of anthophytes are eudicots and include many trees, shrubs, and garden plants. So, this is an incorrect answer.

Option (D) Cycadophyta. The cones contain male and female reproductive structures of cycads and other gymnosperm plants. The plants of this group have large divided leaves and some grow more than 18 m tall. So, this is an incorrect answer.