Which of the following is the best example of an abiotic factor limiting population size? a) the amount of aquatic plants eaten by snails in a pond b) the number of dead standing trees available as nesting sites for downy woodpeckers c) the spread of deadly human flu virus from one person to another by touching and sneezing d) the frequency of rainfall needed for the germination of desert plant seeds

D) the frequency of rainfall needed for the germination of desert plant seeds

Explanation:

When we talk about abiotic factors, we refer to the non-living factors. The abiotic components of an ecosystem include: Water, air, temperature, light, and the like.

So if we consider it as a limiting factor to population size, this should be the cause of the limitation.

Among all the choices, only D, shows an abiotic factor being the cause of population limiting. Rainfall is an abiotic factor (water), which influences the germination of desert plant seeds, specifically, it depends on the frequency of rainfall.

cells use diffusion to get substances in and out of themselves. that diffusion will occur across the cell membrane or the outer covering of the cell. because we are talking about the surface of the cell, surface area and volume are  important factors here. as a cell increases in size, its surface area and volume increase as well.  we call that the surface area to volume ratio (sa: vol).  but the catch is that  volume increases at a greater rate than surface  area. in other words, as a cell gets bigger, the sa: vol gets smaller. so a really small cell like bacteria is mostly cell membrane (surface) with very little contents (volume). a really big cell like an egg, is mostly insides with a super thin membrane. so what ends up happening is that the cell cannot efficiently diffuse all of the stuff it needs in/out to survive. therefore cell size is limited to about 100mm. so how do we make organisms bigger than 100mm? cells divide! by dividing and becoming multicellular, organisms are able to grow!   check out the diagrams i attached to see the effect of sa: vol. i hope this ! good luck!