(problem 18) what is the main reason that geneticists devote so many resources to studying genetics in humans? detailed family records make it particularly easy to study genetics in humans compared with most other organisms. we want to apply what we learn about human genetics to other organisms. very little of what we have learned about genetics in other animals actually applies to humans. we want to understand the many aspects of human health, physiology, and behavior that are influenced by genes. the genetic systems of all other organisms are so poorly developed that useful genetic analysis can only be done with humans.

The Correct answer is "We want to understand the many aspects of human health, physiology, and behavior that are influenced by genes"

The geneticists devote so many resources to studying genetics in humans because they have realized that there are several diseases or physical traits (which may be due to the mutant gene) which are controlled by genes. For example diabetes which was earlier only thought to be regulated by insulin is now known to be as a heretical disease. Also it has been found that genetic diseases that are not present in the parent suddenly appear in their children. This may be due to the presence of recessive traits associated with genes and are being transferred from the forefathers. Not only diseases the physiological characteristics such as skin colour, eye colour, height, hair colour etc are also due to the result of expression of traits carried by the genes.  

In the current scenario the different lifestyle, food and harmful environment conditions also produces genetic variation. Thus it is very important for the geneticist to refer several knowledge resources to understand the expression of gene under varying condition and how it may impact the humans.  

it has to be understood that the sea water contains a huge amount of sodium and chlorine ions and if they enter the cell of the atlantic cod fish, the cell will shrivel and the fish will die. to avoid such a condition, the fish uses active transport for the purpose of removing the ions against the gradient.

explanation:

the atlantic cod is not a maritime osmoconformer. its native application of salts is less than that of the seawater it lives in. it is continually falling water from the gills to the ocean via osmosis.

countering that, the fish is going to be swallowing seawater. but since its internal collection of salts is lower than seawater, the fish will want to go free of excess salt, and since that's going upon a gradient, then active transport, requiring energy, must be used to pump out the salt. much marine fish use the organs to filter out the salt and these fish discharge very straight urine.