The sex cells are called Gametes! Its on Google!
Organisms that reproduce sexually have greater genetic and thus characteristic variations, and so, are able to withstand more selection pressures if they so happen to change or become greater. This increases the chances of survival for that species itself.
Organisms that reproduce asexually are genetically identical to each other. They are unlikely to withstand any changes in selection pressures.
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Answer AND Explanation:
As the population increases, the amount of resources are depleted. Inadequate resources makes the population growth to stop. With a high population, death rate increases due to starvation and diseases which spread more easily in a large population. There may be a decrease in birth rate due to fewer matings and abortions resulting from social stress.
Answer:
In order to propose a hypothesis, there is a need to first see the function of gills in fishes. The gills of fishes comprise blood vessels that exhibit inherited tendencies of getting oxygen out of the water, which was consumed by fishes from their mouths. These gills also comprise thin walls, and when water moves over these walls of blood vessels, the oxygen from water moves into the blood, and then this oxygen-enriched blood goes to various organs.
Thus, one of the hypotheses in the given case, can be the number of blood vessels, which are found in the gills of the mentioned freshwater fish to be higher in comparison to the blood vessels found in the normal fishes, and apart from this, the surface area of the thin walls, which are found in the gills is also more in the new species of freshwater fish.