Think and discuss: Paramecia that live in freshwater have contractile vacuoles, while those that live in salt water do not. Why do you think this is the case

See the answer below

Explanation:

The contractile vacuole primarily functions for the excretion of excess water in organisms that possess the organelle. Paramecia that lives in freshwater would need to constantly get rid of excess water that is likely to be entering the cell due to the fact that the ambient water is hypotonic to their cells. The cytosols of paramecia that live in freshwater have a higher solute concentration and hence, lower water potential than the surrounding freshwater.

The paramecia that live in salt water do not have a need for the contractile vacuole because the problem of excess water entering their cells may not arise. The salt water may not be hypotonic to the cytosol of the paramecia.

hey, i believe your answer would be d. sugar ribose and the base uracil. i believe this is the answer, because rna consists of sugar ribose, adenine, guanine, cytosine, and uracil.

your first option is incorrect, because that's dna. where it consists of sugar deoxyribose, adenine, guanine, cytosine and thymine.

your second option is also incorrect, this is because sugar deoxyribose is in dna, and uracil is in rna. these two do not make sense together.

your third option being incorrect, because sugar ribose is in rna, but not the base of thymine. rna consists of uracil, not thymine.

lastly your fourth option being correct! this answer is correct, because both sugar ribose, and the base uracil are in rna! ~

answer is d. sugar ribose and the base uracil.

it is either c or d and i know for sure it is not a or b