Chapter 15, Problem 3STP

Summary Introduction

Introduction:

Charles Darwin gave a theory of natural selection. He argued that if enough time is given, natural selection could modify a population to produce new species. On the Galapagos Islands, Darwin studied many species of animals and plants that were unique to the islands but similar to species elsewhere. He studied the adaptations in giant tortoises found in Galapagos Islands which contributed to the theory of evolution.

Answer to Problem 3STP

Correct answer :

The correct answer is option D. The Small Island is less grassy, and plants grow with leaves farther above the ground.

Explanation of Solution

Explanation/justification for the correct answer:

Option D. The Small Island is less grassy, and plants grow with leaves farther above the ground.

−According to the illustration give below the two tortoises in different islands differ in their shell size and shape. It is given that tortoises with shells that has higher openings can eat taller plants while those with short neck can feed on vegetation that grows close to the ground. The tortoise on large island has dome shaped shell and short neck; so large island has dense cover of low growing vegetation. The tortoise on Small Island has long neck and high opening on the shell so that it can stretch its neck to reach the tall plants. Hence the Small Island is arid, less grassy and plants grow with leaves farther above the ground.

Hence this is the correct option.

Explanation for incorrect answer:

Option A. Both islands have a dense ground cover of low growing plants−The tortoise on large island has dome shaped shell and short neck; so large island has dense cover of low growing vegetation. The tortoise on Small Island has long neck and high opening on the shell so that it can stretch its neck to reach the tall plants. Hence the Small Island is arid, less grassy and plants grow with leaves farther above the ground.

Hence, this is not the correct option.

Option B. Both islands have similar plants, but vegetation is more spread out on large island- The tortoise on large island has dome shaped shell and short neck; so large island has dense cover of low growing vegetation. The tortoise on Small Island has long neck and high opening on the shell so that it can stretch its neck to reach the tall plants. Hence the Small Island is arid, less grassy and plants grow with leaves farther above the ground. Both islands do not have similar plants.

Hence, this is not the correct option.

Option C. On the large island, the land is almost dry, and only tall trees grow−The tortoise on large island has dome shaped shell and short neck; so it can easily reach the vegetation. This suggests that the large island is humid and has dense cover of low growing vegetation. Hence, this is not the correct option.