Question

Which of the following characteristics is mainly responsible for the diversification of insects on land?
A. Exoskeleton
B. Eyes
C. Segmentation
D. Bilateral symmetry

Answer 1

Insects belong to the largest phylum of Animalia called Arthropoda. Arthropods include two-thirds species. These species come under invertebrates. Arthropods can be classified as millipedes, centipedes, crustaceans, insects and arachnids.

Complete solution:
Insects comes under the class of Hexapods. Hexapods mean six legs. Insects have three-parts of body head, thorax and abdomen; pairs of antennae and compound eyes. Insects are bilaterally symmetrical, segmented, trophoblastic and corporate animals. Ancient insects used to be aquatic organisms. Some of them evolved and adapted to live on the land and result in diversification of insects on land. The most important adaptation is the exoskeleton. Insect exoskeleton is made up of chitinous which help to prevent their skin from drying. Chitin helps to maintain the moisture of insects' skin. Some theory says that insects evolved from crustaceans. Exoskeleton characteristics are mainly responsible for the diversification of insects on land.
So, the correct option is A.

Additional Information: Organisms have two types of skeleton present in the body
A. Endoskeleton
i. Skeleton present inside the body.
ii. Mostly made up of bones.
iii. Amphibians, reptiles, mammals are some examples of endoskeleton animals.
B. Exoskeleton
i. Skeleton present outside the body.
ii. Made up of substance weaker than bone.
iii. Insects, crustaceans, shelled molluscs, etc. are some examples of exoskeleton animals.

Note: Most people consider that a spider is an insect but it is not true. Spider is not an insect because it has eight legs and its body is divided into two parts: head and abdomen. It comes under the class of arachnids meaning eight appendages.