FREE NEET Biology Practice MCQ Test: Organisms And Populations Exercise 4 Questions Answers With Detailed Explanations [PDF]

Answer: (b)

Figure labelled as (A) indicates expanding/triangular age pyramid which designates the large proportion of pre-reproductive age group in comparison with other two age groups.

Figure labelled as (B) indicates stable/bell-shaped age pyramid which symbolises that the pre-reproductive age group is proportionate with the reproductive age group, therefore in the future, the population size of species will remain constant or same.

Figure labelled as (C) represents declining/spindle-shaped age pyramid which shows that the proportion of pre-reproductive age group individuals is quite less than that of the reproductive age group.

Answer: (b)

Answer: (b)

Answer: (d)

Answer: (c)

This option represents the group of basic levels of ecology. Ecology is mainly concerned with four levels of biological organisation, which are

• organisms (basic living unit)
• populations (individuals of a species)
• communities (different sets of population)
• biomes (several biological communities with their associated vegetation or flora).

Answer: (b)

Answer: (a)

Expanding population is a population containing a large proportion of young individuals. Pyramid shaped age structure and urn shaped age structure are the characteristics of expanding population.

Answer: (c)

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. A plot of N in relation to time (t) results in a sigmoid curve. This type of curve is called verhulst pearl logistic curve.

${dN}/{dt} = rN ({K - N}/K)$

where, N = Population density at time ‘t’

r = intrinsic rate of natural increase

K = carrying capacity

Answer: (d)

Competition for light is a critical survival factor among plants living in tropical rain forests.

Answer: (b)

Date rate = ${\text"Number of deaths"}/{\text"Initial number of individuals"}$

= ${200}/{800} = 1/4 = 0.25$

Answer: (c)

Answer: (c)

Lichens represent a positive (beneficial) association called mutualism or symbiosis between two different species, i.e. a fungus and an alga.

Answer: (d)

Interaction between two species, where both suffer adverse effects is known as competition. Competition is the relationship in which each population adversely affects the other in the struggle for resources short in supply.

Competition is of two types – interspecific and intraspecific.

(a) Interspecific competition occurs between two individuals of two different species occurring in a habitat.

(b) Intraspecific competition occurs between individuals of the same species.

Answer: (d)

Statements I, II, III and IV are correct.

Statement V is incorrect and can be corrected as A population of frogs protected from all predators would not increase indefinitely because nature's resources are limited.

Answer: (a)

Commensalism is an association between 2 organisms in which one is benefitted without the other being harmed e.g., Sucker fish has a hold fast and attached itself underside of shark and thus remains protected and also get food left over when shark is feeding on its prey.

Answer: (b)

Parasitism is a relationship between two living organisms of different species in which one organism called parasite obtains its food directly from another living organism called host. The parasite spends a part or whole of its life either on or inside the body of the host. The general parasitic adaptations are (i) anaerobic respiration in internal parasites, (ii) loss of certain organs, (iii) presence of adhesive organs, (iv) excessive multiplication, (v) resistant cysts and eggs for safe transfer of their progeny to new hosts and (vi) well developed and complicated reproductive organs.

Answer: (b)

When in an age pyramid, the number of individuals of reproductive age is lesser than pre - reproductive but higher than post - reproductive ones, then it shows that population is growing.

Answer: (a)

Temperature is very significant to the living beings because the kinetics of enzymes depends on it. Enzymes are very sensitive towards the temperature. A slight decrease or increase in temperature can cause their inactivation or denaturation of enzymes and consequently alter the metabolic activity and physiological functions of an organism.

Answer: (a)

Answer: (a)

Yucca gloriosa has developed an obligate symbiotic relationship with Pronuba yuccasella moth. The moth cannot complete its life cycle with the association of Yucca flowers and in turn Yucca has no other pollinator.