Organisms And Populations

Group of organisms belonging to same species in a particular region or habitat is called as population. Carrying capacity is the maximum population that can be sustained is a particular area. In other words, the number organisms can survive normally in a particular area. The main limiting factor for the carrying capacity is the resources available in the area or the environmental factors. If the environmental conditions are not met then the population will keep decreasing until the resources rebound.
Natality rate is the number of newborns per 1000 in a particular area for a given time. (birth rate).
Mortality is the death rate where it is a measured as number of deaths per 1000 in a particular area for a given time. Predation is the population interaction between predator and prey.

In some plants instead of leaf, the stem performs the function of photosynthesis. The stem modifies into green fleshy leaf like structure. Many succulent xerophytes like Opuntia, Euphorbia etc., store water as mucilagenous substance in special storage tissues of aerial stems. Leaves of such plants are reduced into spines in order to prevent loss of water.

Plants growing on sandy soils are known as psammophytes. Psammophytic plants can be grown on sand and gravel. So, these plants can convert desert areas into green land.

Answer (d) Increase in aerenchyma