Answer:
The nektonic organisms are those marine organisms that are found in almost every depth. These can move freely from one place to another in the ocean body due to its ability to swim. For example, Turtles, sharks, Fishes, and dolphins.
The planktonic organisms are passive swimmers, as they can move along with the ocean currents and are mostly found in the upper portion of the ocean body. For example, Diatoms and Rotifers.
The benthos is the bottom-dwelling organisms that cannot swim. For example, Bivalves, Corals and Sponges.
The nektonic organisms are different from the planktons and the benthos because the nektons can easily swim. They are constructed with such body parts that allow them to swim and migrate from one region to another region within the ocean water body. Whereas the planktons and the benthos cannot migrate easily and are considered as sessile organisms.
The two-layered sac surrounding the heart is the pericardium.
Hope this helps!
<span>Crop
is the part of the digestive system you would see in a cross-section anterior
to the gizzard in a worm. Crop is a thin wall organ that acts as a temporary food
storage chamber. The esophagus leads to the crop and the organ next to it is
the gizzard which serves as the food grinding chamber.</span>
<span>The two factors that determine the shape of a protein </span><span><span>
1. </span> Primary structure. The sequence of amino acids. Amino acids are the building blocks of protein. It is a strong of linearity that can be thousands in length. Moreover, the formation of the amino acid and its system is influenced by its genes’ nucleotides arrangement. </span>
<span><span>2. </span>Hence the next factor is how is the structure of the amino acids bended and folded with itself that forms the certain protein molecule and forms the larger complex structure</span><span>
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