Concept explainers
Exoskeletons and endoskeletons differ in that
a. an exoskeleton is rigid, and an endoskeleton is flexible.
b. endoskeletons are found only in vertebrates.
c. exoskeletons are composed of calcium, and endoskeletons are built from chitin.
d. exoskeletons are external to the soft tissues, and endoskeletons are internal.
Introduction:
There are three types of skeletons that are found in various animals: hydrostatic skeletons (cnidaria), exoskeleton (arthtropods), and endoskeleton (vertebrates). The skeletal system provides the attachment sites for muscles so that they can move against it and helps in locomotion. Skeleton system also supports the body’s structure and provides protection to the organs.
Answer to Problem 1U
Correct answer:
Exoskeleton is present outside the body but endoskeleton is present inside the body. Therefore, option d. is correct.
Explanation of Solution
Reason for the correct statement:
The exoskeleton is very hard and thus provides the animals with protection. It is a layer of chitin seen in insects and crustaceans. On the other hand endoskeleton is inside the body. It can be as hard and rigid as the bones or even flexible like cartilages.
Option d. is given as “exoskeletons are external to the soft tissues, and endoskeletons are internal”.
As, “exoskeletons and endoskeletons differ in that exoskeletons are external to the soft tissues, and endoskeletons are internal”, it is the right answer.
Hence, option d. is correct.
Reasons for the incorrect statements:
Option a. is given as “an exoskeleton is rigid, and an endoskeleton is flexible”.
Exoskeleton is rigid and endoskeleton is both flexible and rigid. So, it is a wrong answer.
Option b. is given as “endoskeletons are found only in vertebrates”.
Endoskeletons are found in vertebrates as well as echinoderms. So, it is a wrong answer.
Option c. is given as “exoskeletons are composed of calcium, and endoskeletons are built from chitin”.
Exoskeletons are composed of chitin and endoskeletons are composed of calcium not the other way around. So, it is a wrong answer.
Hence, options a., b. and c. are incorrect.
Exoskeletons are present outside the animal’s body and endoskeleton is inside the animal’s body.
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Chapter 46 Solutions
EBK BIOLOGY
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