Populations & Ecosystems Test - 7

Ecology is the study of the relationships between living organisms and the abiotic (physico-chemical factors) and biotic components (other species) of their environment. Ecology encompasses the interactions and relationships between organisms and both their non-living (abiotic) and living (biotic) environment. It examines how organisms interact with factors such as climate, water, soil, and other organisms.

Therefore, option a) Abiotic and biotic components accurately describes the scope of ecology.

Interactions between species can have different outcomes. In mutualism, both species benefit from the interaction. This means that there is a mutually beneficial relationship where both species gain advantages, such as access to food, protection, or reproductive assistance.

Option d) Mutualism is the correct answer because it accurately identifies the type of interaction where both species involved benefit from each other.

Thermoregulation refers to the ability of an organism to regulate itsbody temperature . It is the process by which organisms maintain a relatively constant internal temperature despite fluctuations in the external environment. This is achieved through physiological and behavioral mechanisms.

The levels of organization are described below from the smallest to the largest:

• A species is a group of individuals that are genetically related and can breed to produce fertile young. Individuals are not members of the same species if their members cannot produce offspring that can also have children. The second word in the two word name given to every organism is the species name. For example, in Homo sapiens, sapiens is the species name.
• A population is a group of organisms belonging to the same species that live in the same area and interact with one another.
• A community is all of the populations of different species that live in the same area and interact with one another. A community is composed of all of the biotic factors of an area.
• A biome is a community of plants and animals that have common characteristics for the environment they exist in. They can be found over a range of continents. Biomes are distinct biological communities that have formed in response to a shared physical climate.

Hence, Option A is correct.

The principle that states that the superior competitor eliminates the inferior one in competition is the Competitive Exclusion Principle . This principle suggests that when two species compete for the same limited resources in an ecological niche, the species that is better adapted or more efficient at utilizing those resources will eventually outcompete and eliminate the other species from that particular niche.

The correct answer is option a) Competitive exclusion principle. This principle highlights the competitive interactions between species and how competition can lead to the exclusion of one species by another in certain ecological niches.

Exponential growth pattern in population results into j-shaped curve. During exponential growth faster growth occurs and j-shaped curve is formed when time v/s growth is drawn.

In predation and parasitism one species is benefitted while other is harmed. Parasite obtain food from host by harming them.

Populations grow through births and immigration and decline through deaths and emigration.

When resources become progressively limiting for a population, the growth pattern turns logistic. This means that initially, the population may experience exponential growth when resources are abundant and unlimited.

However, as resources start to become scarce and limiting, the growth rate of the population slows down and eventually levels off. This pattern is known as logistic growth.

• Exponential growth (option b) refers to a rapid and unrestricted increase in population size without resource limitations.
• Constant growth (option c) implies a steady and consistent growth rate over time, regardless of resource availability.
• Declining growth (option d) suggests a decrease in population size over time, often due to factors like limited resources or environmental disturbances.

Commensalism is interaction in which one species is benefited by other is neither benefited nor harmed. Orchids growing on mango tree do not harm the mango plants but get shelter.

Population ecology is an important area of ecology because it links ecology to population genetics and evolution. At population level natural selection operates to evolve desired traits.

Inter-specific competition could be most intense and strongest as it occurs between organisms having same types of requirement of food, water etc. They may have competition for food, shelter, water, space or mat also.

Intrinsic rate of natural increase (r) i s a measure of the inherent potential of a population to grow.

The intrinsic rate of natural increase refers to the rate at which a population grows under ideal conditions, assuming unlimited resources and without any limiting factors such as predation, competition, or environmental constraints. It is a measure of the population 's ability to reproduce and survive.

• Birth rate (option b) refers to the rate at which individuals are born in a population.
• Death rate (option c) refers to the rate at which individuals die in a population. While these factors are important in determining population dynamics, the intrinsic rate of natural increase specifically measures the potential for population growth under optimal conditions.
• Carrying capacity (option d) refers to the maximum number of individuals that an environment can sustainably support based on the available resources.

The interaction where one species benefits and the other is unaffected is called commensalism . In this type of interaction, one organism benefits from the association, while the other remains unaffected. Commensalism is characterized by a relationship in which one species gains an advantage or benefit, such as shelter, transportation, or access to food, without causing any harm or benefit to the other species involved.

The correct answer is option d) Commensalism. This type of interaction allows one species to benefit without affecting the other species positively or negatively.

The birth rate of a population = new individual added / previous population. Here birth rate= 7/23=0.3043. Hence, birth rate of Salvinia plants is equal to 0.3.

Sex ratio  is the no of female available per thousands of male in a population. Sex ratio is decline due to female feticides alarmingly in some part of India.