Organism and Population MCQs for NEET — Botany Questions with Answers

The NCERT states, 'Even a plant species, which makes its own food, cannot survive alone; it needs soil microbes to break down the organic matter in soil and return the inorganic nutrients for absorption. And then, how will the plant manage pollination without an animal agent?'

The context states: 'If in a population of size N, the birth rates (not total number but per capita births) are represented as b and death rates (again, per capita death rates) as d, then the increase or decrease in N during a unit time period t (dN/dt) will be dN/dt = (b – d) × N. Let (b–d) = r, then dN/dt = rN.' This is the equation for exponential growth.

The context defines 'r' as: 'Let (b–d) = r'. Here, 'b' represents per capita birth rates and 'd' represents per capita death rates. Therefore, 'r' is the per capita birth rates minus the per capita death rates.

The context states: 'Ideally, when resources in the habitat are unlimited, each species has the ability to realise fully its innate potential to grow in number... Then the population grows in an exponential or geometric fashion.' This clearly indicates that unlimited resources are essential for exponential growth.

The context mentions: 'The above equation describes the exponential or geometric growth pattern of a population (Figure 11.3) and results in a J-shaped curve when we plot N in relation to time.'

The context states: 'Since resources for growth for most animal populations are finite and become limiting sooner or later, the logistic growth model is considered a more realistic one.'

The context describes logistic growth as: 'A population growing in a habitat with limited resources show initially a lag phase, followed by phases of acceleration and deceleration and finally an asymptote, when the population density reaches the carrying capacity.'

The context explicitly defines K as 'K = Carrying capacity'.

The 'r' value is the 'intrinsic rate of natural increase'. A higher 'r' value indicates a greater potential for population growth. Since 0.12 (flour beetle) is greater than 0.015 (Norway rat), flour beetles have a higher intrinsic rate of natural increase.

The context states: 'Where $N_t$ = Population density after time t, $N_0$ = Population density at time zero, r = intrinsic rate of natural increase, e = the base of natural logarithms (2.71828)'.