Answer:
keratin.
Explanation:
<em>keratin is a fibrous protein that has protective and structural functions in the body. </em>
<em>to fulfil it's functional necessities keratin has characteristics that makes it insoluble and repellent to damage.</em>
<em>to fulfil it's functional necessities keratin has characteristics that makes it insoluble and repellent to damage.in the human body, keratin can be present in - hair and finger nails. </em>
hope it helps. :)
It depends on what you’re learning, a possible answer is bias.
Sponges are similar to other animals in that they are multicellular, heterotrophic, lack cell walls and produce sperm cells. Unlike other animals, they lack true tissues and organs, and have no body symmetry.
The shapes of their bodies are adapted for maximal efficiency of water
flow through the central cavity, where it deposits nutrients, and leaves
through a hole called the osculum. Many sponges have internal skeletons of spongin and/or spicules of calcium carbonate or silicon dioxide. All sponges are sessile
aquatic animals. Although there are freshwater species, the great
majority are marine (salt water) species, ranging from tidal zones to
depths exceeding 8,800 m (5.5 mi).
