Cnidarians have specialized cells known as cnidocytes (“stinging cells”) containing organelles called nematocysts. These cells are concentrated around the mouth and tentacles of the animal and can immobilize prey with toxins. Nematocysts contain coiled threads that may bear barbs.
The structure of plasma membrane makes it selectively permeable allowing it to regulate the passage of substances into and out of the cell. Small nonpolar molecules can easily across the phospholipid bilayer of plasma membrane because it is hydrophobic. Polar molecules and ion cannot easily across the hydrophobic portion of plasma membrane because it is hydrophilic. Polar molecules and ions usually across the plasma membrane with the help of transport proteins.
The whale's flipper and tail flukes and fish fins are analogous structure as they have different structural formation but they perform the same function.
Flipper and tails are locomotory organs in the whale and helps the whale in propelling similarly fins in the fish assist the fish in swimming. Both the strcutures have evolved differently and are made of different materials.
2. High birth rate, zero death rate, high immigration, zero emigration
This is because birth rate and immigration increase population size, and death rate and emigration decrease population size, so maximizing the former and minimizing the latter are ideal
