Answer:
exoskeleton (from Greek έξω, éxō "outer" and σκελετός, skeletós "skeleton"[1]) is the external skeleton that supports and protects an animal's body, in contrast to the internal skeleton (endoskeleton) of, for example, a human. In usage, some of the larger kinds of exoskeletons are known as "shells". Examples of animals with exoskeletons include insects such as grasshoppers and cockroaches, and crustaceans such as crabs and lobsters, as well as the shells of certain sponges and the various groups of shelled molluscs, including those of snails, clams, tusk shells, chitons and nautilus. Some animals, such as the tortoise and turtle (shell page), have both an endoskeleton and an exoskeleton.
The general term for a large molecule made up of many similar subunits is called a polymer.
If an animal is having a well developed skeleton system, a backbone then it belongs to vertebrate. Also, size is an important factor to identify vertebrate and invertebrate.
Explanation:
Vertebrates have a well developed skeleton system and backbone. Their skeleton system is made up of bones and cartilage. While, invertebrates don't have any backbone.
Due to lack of backbone or skeleton system, invertebrates are small in size. As there is no proper mechanism to support large body so invertebrates are small in size and also they move very slowly. This is also a major difference in vertebrate and invertebrate.
Another important difference between vertebrate and invertebrate is that body of vertebrate is covered with some structure like hair, feathers, skin, scales or a combination of these.
These features help to distinguish vertebrate from invertebrate by observing them, no need to dissect.
The DNA (deoxyribonucleic acid) is the double helical in structure. It has two anti parallel strands of long polynucleotides. The nucleotides are two purines ( adenine and guanine) and two pyrimidines ( thymine and cytosine). These purines and pyrimidines are attached with their complementary. Adenine pairs with the thymine with the two hydrogen bonds and the guanine pair with cytosine by three hydrogen bonds. The two strands are twisted which is responsible for the helical structure. The overall charge on the DNA molecule is the negative charge.
