Ecology: Organism and Its Environment: Definition, Characteristics, Classification, Characteristics, Types

What is Ecology?

Ecology is a branch of biology that deals with the assessment of the relations of living things with each other and with their surroundings, both biotic and abiotic components. Ecology is a vital subject because it helps to determine the interactions between living organisms and their surroundings, as well as the consequences that arise from human interference with the environment.

It is the academic discipline concerned with nature’s balance and resilience as well as the efficient and environmentally friendly use of the earth’s natural resources. Ecologists want to understand how organisms interact with the world around them to learn about the factors affecting the mechanics of population, the community of organisms, and the processes of ecosystems to further enable the preservation of habitats.

Levels of Organisation in Ecology

There are four distinct organisational levels in ecology. They are as follows:

Individual Organism (Adaptations & Survival)

A population is a set of individual organisms that are living and possess the properties of life, for instance, metabolism, growth, reproduction, and differentiated response to stimuli. Thus, the organism is the cell of the biological hierarchy acting independently to sustain its equilibriums and reproduce.

In order to maintain proper functioning, some characteristics are necessary for the organisms’ existence in the environment. Such modifications may be morphological, mechanical, or chemical, enabling the organisms to optimise resources and accommodate environmental stresses.

Example: Desert plants and water conservation

Some of the plant adaptations that are likely to be seen include those commonly found in plants growing in the desert, examples being the cactus and the succulents. It either has thick fleshy stems or leaves which hold water, a small number of leaves to reduce the rate of evaporation, or deep and spread roots to increase the area for water absorption. Some have the creosote bush, which has leaves that are covered by a waxy film to minimize their rate of transpiration. These changes allow them to live and reproduce in conditions that limit the availability of water in deserts.

Population (Growth Models, Factors, Examples)

Population is the total of humans, animals, plants or any living organisms of similar species which are living in a specific geographical area and have intercourse among themselves. Population contains certain attributes like its magnitude, distribution as counted by geographical area per head, and age composition.

Population growth models help to understand how populations change in size over time. Two models are:

Factors affecting population size are:

Example: Population dynamics of rabbits in a forest

The major factors that affect the population of rabbits in a forest include food factors (plants), foxes/owls, disease, or conditions of the habitat. Such change in circumstances may lead to the rabbit population rapidly increasing in the short term, such as during situations characterized by food abundance and low predatory pressure. Nevertheless, as the population rises competition for food improves and predators may intensify which causes development to be logistic. Other factors that can lead to changes in population number are; environmental hazards; for Example; harsh winters that can lead to loss of lives.

Community (Species Interactions & Keystone Species)

A community is said to be a group of species living within the same geographical region. The extent of species and the relations between them are its main features. Different types species interactions are:

Ecosystem (Trophic Levels, Energy Pyramid, Cycles)

An ecosystem is a population with interactions between the organisms and their environment. They are the biotic or the living and the abiotic or the non-living factors.

In trophic levels, organisms are arranged in tiers according to their location in the food chain ranging from producers to primary, secondary, and tertiary consumers. Energy value gradually declines with the increase in the trophic level.

Energy Pyramid is one of the ecological pyramids that explains how energy moves from one trophic level to another with the producers forming the lowest level while the top consumers, or the predators, form the highest level.

Examples include:

• In pollination, both the plants and bees have a benefit where plants are on the receiving end of pollination and the other extreme bees have a benefit in that they get to feed on nectar as well as get a chance to collect pollen.

• Nitrogen fixation is a mutualism because there are nutritive benefits for the leguminous plants and nitrogen-fixing bacteria whereby the bacteria benefit from organic nitrogen in reciprocation to the plants.

Components of the Environment

The components of the environment are listed below-

Biotic Factors

Biotic factors are living organisms such as plants, and animals and microorganisms such as bacteria and fungi that influence Biomes. However, entities inhabiting a given environment are categorized in trophic levels depending on their position in the food web through the feeding hierarchy.

Example: Decomposers feed on dead organisms and recycle nutrients such as nitrogen and phosphorus back to the environment to be purchased by plants.

Abiotic Factors

Abiotic factors encompass nonliving components of the organism and ecosystems for instance heat, water, light, and soil and among others. These factors describe the habitats of various organisms in terms of their physical and their observable characteristics and locations.

Example: Characteristics of desert plants and animals have mechanisms of conserving water that do well in the hot environment.

Ecological Interactions

The ecological interactions are listed below-

Competition (Intraspecific, Interspecific, Competitive Exclusion)

There are two types of competition:

• Intraspecific: This can be defined as an affair whereby the members of the same species tend to struggle for optimal access to useful factors such as food, shelter or even females or males depending on the species.

• Interspecific: It refers to the act of struggle where two or more people fight for available resources perhaps due to their self-assertiveness of power or dominance rather than species.

Competitive exclusion principle states that when two species engage in a competitive relationship through a given limiting resource, they cannot persist simultaneously in the same ecological site. One species will drive the other to the local exclusion or they will partition resources and their ranges.

Example: Lions and hyenas competing for prey

For instance, lions and hyenas, two carnivorous animals are bitter enemies mainly because of the struggle for food in the savannahs where animals such as zebras and antelopes can easily be hunted Lions view these hyenas as potential rivals seeing that the Lions used to hunt for the same prey exclusively. Because of the similarity in diet and the instances of geographical overlapping, the relations involve frequent attacks and competition for the intake of leftovers.

Predation (Dynamics, Adaptations, Examples)

Predation is the process in which one species which is called the predator, pursues and kills another species known as the prey, to feed on it. As such, it possesses a contiguous impact on population density and dispersion and also community structure.

Carnivores have also developed strategies such that they include the ability to hide, sharp vision, and the ability to run very fast to hunt prey. Evidence that prey species may evolve defence responses includes; camouflage, warning colouration, and physical defence like; spines, shells etc.

Example: Arctic fox and lemming predator-prey relationship

Lemmings are reported to be the prime diet of the Arctic foxes, especially in the Arctic tundra region. The food distribution of lemmings, their population and scarcity define the cycles of Arctic foxes and in fact, show the predator-prey relations naturally.

Mutualism (Pollination, Nitrogen Fixation)

Interdependence interactions involve two species and this particular type of relationship benefits the two species in question, and the kind of relationship they have is called mutualism.

Examples include pollination in which both the plants and bees have a benefit, nitrogen fixation in which there are nutritive benefits for the leguminous plants and nitrogen-fixing bacteria.

Symbiotic relationships where the two species require each other to survive and facultative where there is a need for benefit but it is not very crucial.

Example: Bee and flower mutualism

They provide honey for their food and at the same time they help in the process of pollination of flowers throughout the process of nectar and pollen collection. They are mutualistic organisms, which means that bees and flowers will only benefit from one another’s existence and subsequent production of offspring.

Commensalism and Parasitism

Commensalism is when one species benefits with the other being unimpaired in any way. For instance, barnacles cling themselves to the body of the whale to get close to nutrient-rich water currents without causing harm to the mammal.

Parasitism is when one organism gains something by living off another organism, which could be clipped or killed. These include, for instance, ticks drawing blood from mammals or tapeworms taking nutrients from the host’s intestine.

Ecology NEET MCQs (With Answers & Explanations)

Important topics from the chapter for NEET preparation:

• Population Interactions e.g., mutualism, predation, competition, parasitism, and commensalism.

• Population Attributes such as population size, density, age distribution, birth rate, and mortality rate

• Population Growth Models

• Biotic and Abiotic Factors

Practice Questions for NEET

Q1. Green revolution in India occurred during:

1. 1970's

2. 1980's

3. 1950's

4. 1960's

Correct answer: 4) 1960's

Explanation:

The green revolution in India occurred in the mid-1960s, through the introduction of high-yield crop varieties and the application of modern agricultural techniques, and led to an increase in food production in India.

Hence, the correct answer is option 4) 1960's

Q2. Which of the following is not a type of biomes

1. Tundra

2. Tropical forest

3. Grassland

4. None of the above

Correct answer: 4) None of the above

Explanation:

The tundra region gets the least amount of sunlight. This area has a very cold climate. Snow is falling, and only a few plants, shrubs, grasses, lichens, and mosses can be found. This habitat can be found in the Arctic.

Tropical forests are found near tropical areas and experience heavy rainfall and hot temperatures. They have a diverse ecosystem. Buttresses, vines, and epiphytes can be found here. Tropical forests can be found in areas of South America, Africa, and Southeast Asia.

Grasslands are found in areas with high temperatures and low moisture. As a result, the flora is dominated by tall grasses, and trees are limited. The grassland is a habitat for a variety of animals that feed on grass. Prairie in North America, pampas in South America, veld in Southern Africa, downs in Australia, and steppe in Asia are all names for this environment.

Hence, the correct answer is option 4) None of the above.

Q3. When an animal group is centered around a dominant female, it is called

1. Patriarchy

2. Matriarchy

3. Swarm

4. Flock

Correct answer: 2) Matriarchy

Explanation:

When an animal group is centred around a dominant female, it is more accurately referred to as a "matriarchy." Matriarchy typically refers to a social system or cultural organization in which women hold the primary positions of power and authority in society.

In certain animal species, particularly some primates such as bonobos and some elephants, social structures can be matriarchal. In these societies, a dominant female, often the oldest and most experienced, holds a central position of leadership and influence within the group. The dominant female may make decisions regarding the group's movements, foraging, and social interactions.

It's important to note that while matriarchal societies exist in certain animal species, they should not be directly equated with human concepts of matriarchy, which often involve complex social, cultural, and political dynamics. Animal matriarchal societies are primarily defined by the dominance and leadership of a female individual, whereas human matriarchy encompasses broader societal structures and power dynamics.

Hence, the correct answer is option 2) Matriarchy.

Also Read:

• MCQs on Ecology, Organisms and its Environment

• Biotic and Abiotic

• Bacterial Growth Curve

Ecological Interactions