What problem is faced by organisms that live in fresh water?
their bodies tend to take in too much water.
they have no way of controlling their tonicity.
only salt water poses problems for animals that live in it.
their bodies tend to lose too much water to their environment.

A. Their bodies tend to take in too much water.

Explanation:

Osmoregulation is the maintenance of osmotic concentration inside the body cells and in the extracellular fluid by controlling the amount of water and salts.  Organisms living in water can be divided into two groups: Some are osmoconformers which change the osmolarity of body fluids with respect to the surrounding medium. Some are osmoregulators which do not allow change in internal osmolarity and try to maintain it by various means.

If as osmoregulator is placed in fresh water environment then their body is hypertonic to their environment. Osmosis will occur which is the movement of water from low solute to high solute concentration. Thus the problems faced by such organisms would be:

- Entry of excess water

- Loss of body salts to outside.

Adaptations in such organisms would be:

- Body cover such as scales or adipose covers

- They do not drink more water

- Excess water is eliminated as dilute urine

- Special cells called ionocytes or chloride cells help in active uptake of sodium ions and chloride ions.

hydroxyl -oh

alcohols, always polar, can form hydrogen bonds with h2o molecules

carboxyl -cooh  

cargoxylic acids, has acidic properties which is a source of hydrogen ions, found in cells in ionized for with a charge of oh-1

carbonyl > co

ketone if within skeleton, aldehyde if group is at the end of skeleton, k & a may be structural isomers, it determines 2 sugars (ketose & aldose)

amino -nh2

amines, acts as a base, it can pick up h+ ions from surrounding solution, ionized with charge of 1+

methyl ch2

addition to rna/dna affects and gene expression

phosphate -opo3 ²⁻

organic phosphates, contributes to negative charge to, molecule that it is a part of, and potential to react with h20

sulfhydryl -sh

thiols, cross-linking stabilize the protein, and it is structure

tsd is temerature dependent sex determination.

tsd: it is a type of environmental sex determination in which the temperature experienced during embryonic/ larval development (ambient temperature for development) determine the sex of the offspring.

crocodile displays the tsd where the ambient temperature of the developing egg determines the individual's sex. for example in the american alligator's eggs, incubation at 33 ºc produces mostly males, while incubation at 30 ºc produces mostly females. so if the american alligator's egg will get the ambient temperature (33 degree celcius)during embryonic development from egg, the offspring will be male and same for the female sex determination.