NEET Practice Questions (MCQs) with Answers & Solutions

(d) In logistic growth model population growth equation is described as

             dN/dt = rN(K-N)/K

 where, N = Population density at time t

           r = Intrinsic rate of natural increase

          K = Carrying capacity

when, N/K = 1 then (K-N)/K = 0

Therefore, dN/dt = 0

An association of individuals of different species living in the same habitat and having functional interaction is called biotic community (biocoenosis). The biotic community is dominated by one of the character. It determines the nature of community. It can be biotic or abiotic.

Competition is a negative interaction that occurs among organisms whenever two or more organisms require the same limited resource. 

(d) Every year in the season of winter the famous Indian National Park, Keolado  National Park situated in Bharatput, Rajasthan, host thousands of migratory birds coming from Siberia (Atlantic ocean) Central America and other extremely cold Northern region.

October to February is the best time to observe these migratory birds. Most of them stay till March including the Siberian Crane.

(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.