Whats a model that's the size and shape of a cell?

As my Knowladge the cell has round shape in more times

sexual reproduction produces offspring with novel combinations of genes. species that reproduce sexually must maintain two different types of individuals, males and females, which can limit the ability to colonize new habitats as both sexes must be present.

as resources become scarce because of population growth, the growth decreases after few years due to lack of resources and food.