All questions of Organisms and Environment for NEET Exam

(d) Competition occurs for light, food and space among organisms in which all partners are adversely affected in an ecosystom.

Cuscuta, or Dodder plant, is a parasitic plant that wraps around other plants for nourishment. Cuscuta is found on outer side of the host and is total stem parasite. Cuscuta a parasite of Acacia.

(c) Gause's principle of competitive exclusion can be restated to say that no two species can occupy the same niche indefinitely when resources are limiting. Certainly species can and do coexist while competing for some of the same resources. Nevertheless, Gause's theory predicts that when two species coexist on a long-term basis, either resources must not be limited or their niches will always differ in one or more features; otherwise, one species will outcompete the other and the extinction of the second species will inevitably result, a process referred to as competitive exclusion

Species facing competition might evolve mechanism that promotes co-existence rather exclusion. One such mechanism is resource partitioning. 

Resource partitioning is the division of limited resources by species to help avoid competition in an ecological niche. Example - carnivorous animals like lions, leopards occupy the same niche but lions predate mostly larger animals and leopards take smaller ones.

So, correct answer is option C.

Carrying capacity refers to the maximum number of individuals that can be sustained by the environment. Birth rate refers to number of births per unit population.

Species interaction refers to direct and indirect interrelationship between different organisms, while on the other hand population attributes include population size, population density, population spacing, and age structure. Mortality is the ratio of deaths in an area to the population of that area; expressed per 1000 per year. Sex ratio is  the ratio of males to females in a population.

The formula of exponential growth is  is the rate of change in population size, r is the biotic potential and N is the population size.

If a population (e.g reindeer population) is allowed to grow in a predator free environment, the population grows beyond carrying capacity and there occurs population crash due to sudden shortage of food. Such growth curves also occur in insect populations during rainy season, and in algal blooms.

The growth curve for bacteria is sigmoid. First phase is the phase of slow growth- Lag phase. Second phase is the period of accelerated growth - Log phase. Third phase is the phase when growth rate  becomes stable - Stationary phase. Finally growth rate declines.

While they do not rule out the occurrence of interspecific competition in nature, they point out that species facing competition might evolve mechanisms that promote co-existence rather than exclusion. One such mechanism is ‘resource partitioning’.

Gause's 'Competitive Exclusion Principle' states that two closely related species competing for the same resources cannot co-exist indefinitely and the competitively inferior one will be eliminated eventaully. Thus, statement I is correct.
Statement II is incorrect as in general, herbivores and plants appear to be more adversely affected by competition than carnivores. 

Geometric representation of age structure a characteristic of population.

Desert show maximum difference between day and night temperature.

Asymptote in a logistic growth curve is obtained when population density (N) reaches the carrying capacity (K), i.e., N = K.

Praying mantis is a good example of camouflage. Camouflage is the natural colouring of an animal which enables it to blend in with its surroundings.
A praying mantis, or praying mantid, is the common name for an insect of the order Mantodea. Often mistakenly spelled preying mantis (a tempting mistake, as they are notoriously predatory) they are in fact named for the typical “prayer-like” stance. The word mantis derives from the Greek word mantis for prophet or fortune teller. A praying mantis from India

So, the correct match is : A-II, B-I, C-III, D-IV.

In predation, one species is benefited where as the other is harmed. It is (+ −) type of population interaction.

One of the species in predation gains benefit on the expense of the other. Predators help in maintaining species diversity in a community, by reducing the intensity of competition among competing prey species. If a predator is too efficient and overexploits its prey, then the prey might become extinct.

In the sigmoid growth cur ve growth is slow in the lag phase. Growth rate remains stable during the stationary phase and it declines during the senescent phase. Growth increases logarithmically during the exponential phase.

Competition occurs for light, food and space among organisms in which all partners are adversely affected in an ecosystom.

 

The Verhulst-Pearl logistic growth equation you've presented is a fundamental model used to describe how populations grow under limited resource conditions. This model is sensitive to both the variables and coefficients it incorporates:

Here:
N represents the population size at time t.
r  is the intrinsic rate of natural increase, indicating the rate at which the population grows per individual when resources are not limiting.
K represents the carrying capacity of the environment.
In the context of this equation:
The term  is a fraction that reduces the effective growth rate as the population size N approaches the carrying capacity K. This term essentially represents the remaining proportion of resources available as the population grows larger.
Based on this understanding:
Option A: "Intrinsic rate of natural increase" – Incorrect, this is represented by r in the equation.
Option B: "Biotic potential" – Incorrect, biotic potential generally refers to the maximum reproductive capacity of an organism under optimal conditions, often considered similar to r but not specifically the same as K.
Option C: "Carrying capacity" – Correct, as K in the equation is specifically describing the carrying capacity, which is the maximum population size that the environment can sustain indefinitely given the food, habitat, water, and other necessities available in the environment. Option D: "Population density" – Incorrect, while N relates directly to population density at any time, K is about the upper limit of that density sustainable by the environment. Therefore, Option C is the correct answer. The variable K in the Verhulst-Pearl logistic growth equation indeed stands for the carrying capacity.

Given this information, the correct match is :
Option D : A-I, B-II, C-III, D-IV