Organism and Population MCQs for NEET — Botany Questions with Answers

(b) Geometric representation of age structure is a characteristic of population. In most populations, individuals are of different ages. The proportion of individual in each age group is called age structure of that population.

((b) Intraspecific competition is an important density dependent factor regulating populations.  Intraspecific competition occurs between the members of same population.

Praying mantis (Mantis religiosa) is a large insect. It has small triangular head, a long prothrax and abdomen consisting of 10 segments. The wings are well developed and the pincer-like forelegs are modified for grasping prey. It usually inhabits plantation areas. It destroys certain harmful insects so it is useful. The praying mantis can camouflage perfectly into an environment of sticks, bark, leaves and flowers.

ln J-shaped form of population growth, the density increases in an exponential manner and then a crash occurs or the increase stops abruptly as environmental resistance becomes effective.This is mathematically described by an equation of exponential or geometric increase, which is as follows:-

dN/dt = rN

where,
d = rate of change
t = time
N = number of females at a particular time
r = biotic potential of each female
(N can also be considered as the total population and r as the biotic potential of each individual)

Salamander is semi terrestrial lizard-like tailed amphibian lives under stones, logs and inside crevices. They show hibernation.

Salmon are anadromous i.e., they spend their adult lives at sea but return to fresh water to spawn. The pacific species is legendary : after migrating downstream as a smolt a sockeye salmon ranges many hundred of miles over the pacific for nearly four years and then returns to spawn in the head water of its parent stream. Migration is characteristic feature of birds. Arctic tern travels about 1100 miles during winter and return back during summer.

(d) Competition is a type of negative interaction which develops between two or more organisms using the same resource, if the resources are insufficient to fulfill their demands. The competition within the members of same species is termed as intraspecific competition while the competition between two species is termed as interspecific competition. Competition increases with population density. 

(c) Mutualism is an obligatory positive interspecific interaction stongly beneficial to both species. The unicellular photosynthetic algae, called Zoochlorellae live symbiotically in the outer tissues of coelenterates. Algae are photosynthetic and produce oxygen and food beneficial to hosts and in exchange they obtain materials like carbon dioxide and nitrogenous wastes released by metabolism of host animals.  

(a) World population day - 11th July

No tobacco day - 31st May

World environment day - 5th June

World health day - 7th April

(a) The predator develops a preference to other diets and can give unforeseen negative results that could outweigh all benefits. For example, when the mongoose was introduced in Hawaii in order to control the rat population, it preyed on the endemic birds of Hawaii, especially their eggs, more often than it ate the rats. As most of the birds feed on insect and keep insect population low. The mongoose who destroy birds acts as secondary pest.

(d) Symbiosis means "living together". It is a beneficial coaction between two (or more) different species in which one or both the species are benefited and neither species is harmed. Symbiotic relationships are manifested through commensalism, protocooperation and mutualism and are widespread in nature. Commensalism is an association or relationship between two different organisms in which one is always benefitted while the other is neither benefitted nor harmed. This relationship may be permanent or temporary and the benefit derived from the other organism may consist of protection, transportation, living space and food. Protocooperation is a relationship between two or more individuals of different species in which all are benefitted by one another.