NEET Study Notes for Ecology and Environment: Ecology term was first coined by Ernst Haeckel. The study of the interaction between biotic and abiotic components is called Ecology. Ecosystem is the structural and functional unit of the environment. Ecosystem may be large or small. The ecosystem is mainly composed of biotic and abiotic components.

• Topics like Organisms and Environment, Ecosystem, Biodiversity and Conversation and Environmental issues come under the broad topic of Ecology and Environment that carry a weightage of around 8-9 questions in NEET Biology Syllabus.
• With a thorough understanding of the topics in Ecology and Environment, candidates can score easily from the questions in this topic in NEET 2022. 

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Important Topics in NEET Ecology and Environment

NEET Study Notes for Ecology and Environment

Environment can be defined as the sum total of all biotic and abiotic components that surround and have the potential to influence organisms.

Habitat- The natural environment of an organism is known as the Habitat of the organism.

Niche- Niche includes resources and conditions that an organism requires. Organism's functional role is also defined.

The ecosystem is composed of two components:

• Biotic Components- Biotic Components are the living organisms within an ecosystem. Biotic components can be divided into producer, consumer, and decomposer.
• Abiotic Components- Abiotic components include non-living components, inorganic substances or minerals, organic substances, and atmospheric factors.

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Population Ecological Adaptations

The members of interbreeding species that live in a geographic area are called Population.

Population attributes

Population attributes include birth rate/ nationality, sex ratio, population density, death rates, age distribution.

Population Density-

The number of individuals that are present per unit area or volume at a specific point of time is called population density. Example- number of animals per square kilometer, number of trees per area in a forest.

Population Growth-

Factors that determine population growth are mainly birth rate, death rate, people immigrating, and the number of people emigrating. There are two main growth models:

• Exponential Growth- Unlimited supply of food and resources leads to exponential growth. In this case, the specific organism will increase exponentially.
• Logistic Growth- When there is exponential growth, competition arises between individuals as there are only limited resources. This leads to a lag phase initially Acceleration and deceleration follows it. Logistic growth is depicted by a sigmoid curve. This is also known as Verhulst- Pearl Logistic Growth.

The equation for Verhulst- Pearl Logistic Growth is:

where N= Population density (at a point of time)

r = natural increase intrinsic rate

K = carrying capacity

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Population Interaction-

Population Interaction is defined as the interdependence interaction as the members of the community depend upon one another for food, reproduction, production, etc. There can be positive as well as negative interactions amongst the population. In positive interactions, the interacting species members are not harmed but benefit. In negative species, either or both of the species interacting are harmed.

• Mutualism- Mutualism is a positive interaction in which the species interacting are interdependent for growth and survival. There is physical contact and an obligatory relationship between the species. Examples are - flowers and butterflies, Lichens( algae and fungi), Mycorrhizal ( fungi and higher plants).
• Parasitism This is a type of negative interaction in which, the parasite gets nourishment and shelter from the host. In this interaction, the host is harmed but benefits the other species interacting (parasite). Examples- Disease pathogens (plants and animals), Cuscuta parasite on hedge plant.
• Predation- This is another type of negative relationship in which, one organism predates (kills) the other for nourishment and food. Examples- Carnivores Animals, Insectivores Fungi and Insectivores Plant.
• Competition- In this relationship, both species are adversely affected. Competition can be of two types- Interspecific and Intraspecific competition. Interaction between different species who belong to the same habitat is Interspecific competition whereas competition between same species individuals is Intraspecific competition.

NEET Study Notes on Ecosystem

Productivity- Productivity in an ecosystem is the rate of biomass production or the organic matter accumulated per unit area, per unit time. It can be expressed as g–2 yr –1 or (kcal m–2) yr–1.

Productivity is mainly of two types Primary Productivity and Secondary Productivity

• Primary Productivity- Primary Productivity is the biomass or organic matter that is produced in duration by plants by photosynthesis in per unit area. It depends on plant species and other environmental factors like availability of nutrients, the capacity of plants for photosynthesis
• Secondary Productivity- The rate of formation of new organic matter by consumers Secondary Productivity is a reflection of foot utilization for consumer biomass production.

Decomposition- When complex organic material, dead minerals, or plants are converted into mineral substances for the soil so that it is the best resource for other minerals. The decomposition process occurs primarily on the upper layer of soil.

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Energy Flow

• Energy cannot be created or destroyed but can be transformed from one form to another. This transfer of energy from one level to another is called Energy Flow.
• Energy Flow is unidirectional in an ecosystem. When energy is transferred from one level to another, a large amount of energy is lost.
• Thus the amount of energy that is transferred from one level to another is less.
• This also leads to loss of energy in the form of heat, due to metabolic activity.

Pyramids

The ecological parameters are represented at different trophic levels. In the ecosystem. These are called Pyramids. There are three types of pyramids- Pyramids of number, Pyramids of Energy, and Pyramids of Biomass.

• Pyramids of Number- The graphical representation of the strength in numerical terms of diverse populations in trophic levels per unit area of the ecosystem is called Pyramids of Numbers. The producers form the base, intermediate levels form intermediate tiers and the apex is formed by top carnivores.
• Pyramids of Biomass- Graphical Representation of biomass produced per unit area in rising trophic level are Pyramids of Biomass. Producers are at the base whereas carnivores are at the top of the apex.
• Pyramids of Energy- Graphical Representation of energy at various trophic levels are Pyramids of Energy. Since there is a gradual decrease of energy as the trophic level increases, Pyramids of energy are always upright.

Ecological Efficiency

Energy transferred from one trophic level to other can be defined in terms of percentage. This is called ecological efficiency. Ecological Efficiency can be expressed as assimilation, net production, photosynthetic, and ecological efficiency.

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What is the Nutrient Cycle?

The materials that are required by the ecosystem exist continuously in the system through the process of cycling. The constant exchange of such materials ( in addition to energy) between living organisms and the abiotic environment is called the nutrient cycle or the biogeochemical cycle.

Ecological Succession

• Ecological Succession is the development of a plant community in a barren area is called Ecological Succession.
• The characteristics of Ecological Succession include the replacement of a short-lived plant by a long-lived plant, net community productivity is decreased.
• The causes of succession are biotic factors and physiographic factors like soil erosion, landslides, volcanic lava, etc.

Ecological Services

• Services that humankind benefits from multiple resources and are processed from the natural ecosystem are called ecological services.
• Examples of Ecological Services are carbon fixation, oxygen, pollination, etc.
• Such Ecological services can also be divided into provisioning, regulating, supporting, cultural and preserving, etc.

NEET Study Notes on Biodiversity

The existence of ecosystems of different types, organisms of different species, genes, and environment along with interaction is Biodiversity.

• The three hierarchical levels in Biodiversity are- genetic diversity, species diversity and ecological diversity.
• Genetic diversity- The variation of genes within species is called genetic diversity. Such differences could be in the structure of chromosomes or differences in alleles.
• Species diversity- the diversity in the species of a region is called species diversity.
• Ecological diversity- The diversity of niches, trophic levels, and ecological processes which maintain the flow of energy, food web, and nutrient recycling is called ecological diversity.

Biodiversity Conservation

• The biodiversity of the earth forms the basis of mankind's survival.
• Biodiversity Conservation is necessary due to reasons of utilitarian (narrow), broad (utilitarian ), and ethical.
• Biodiversity provides us with several direct as well as indirect benefits that help in our survival.
• The IUCN (International Union for Conservation of Nature and Natural Resources) maintains a book that consists of plants and animals that are known to be in danger, this is called a Red Data Book.

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NEET Study Notes on Environmental Issues

Changes in physical, chemical, and biological characteristics of the environment that harm life on earth is called Pollution. Pollution can be categorized into - Air Pollution, Water, Soil, Noise, and Radioactive Pollution.

Air Pollution

• The occurrence of gases, pollutants, foreign particles in the air that adversely impact human beings, animals, and vegetation leads to air pollution.
• Two categories that cause air pollution are gaseous materials and particulate matter.
• The gaseous materials include ethylene, nitrogen oxide, sulfur oxide, Carbon monoxide, and other gases and vapors that have a boiling point of less than 200C.
• Particulate matter includes soot, smoke, dust, fibers, pesticides, and also biological agents like dust mites.

Control of Air Pollution

• Particulate matter that is released in Air can be removed using Arresters and Scrubbers. Arresters are used in the separation of particulate matter from the air that is polluted. Two types of Arresters that can be used are Cyclonic Separators and Electronic precipitators.
• Wet and dry scrubbers can be used for dust separation
• To control gaseous pollutants, techniques like Combustion, Absorption, and Adsorption can be used.
• In combustion, gaseous pollutants that are oxidizable are burnt at high temperatures. Examples- Petrochemicals, fertilizers, varnish industries.
• Absorption- Pollutants that are gaseous in nature are are absorbed by absorbing materials.
• Adsorption- Toxic gases, vapors, and other pollutants that cannot be removed by other techniques are adsorbed by large solid surfaces.

Radioactive Pollution

• Emission of charged particles and radiation by atomic nuclei decay is called radioactivity. The elements that cause these are called radioactive elements.
• Radioactive Pollution not only plays a part in air, water, and soil pollution but also harms living organisms.
• The sources of Radioactive Pollution are natural like Cosmic Rays, Man-made radiation like radiation released during mining, producing nuclear weapons, etc, and Other sources like radioactive elements used in laboratories.

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Agrochemicals and their effects

• When synthetic fertilizers, pesticides, plant growth regulars are used as agrochemicals they have an adverse impact on the environment.
• Organic Farming involves the process of crop rotation, crop residues, animal manures, and cultivation mechanically to enhance the soil level.
• The harmful effects of agrochemicals lead to a reduction in soil fertility, soil erosion, and harmful to microorganisms and earthworms that are beneficial to the soil.

NEET Sample MCQs for Ecology and Environment

Question: What is generally a man-made greenhouse gas?

1. Nitrous Oxide
2. Chlorofluorocarbons
3. Carbon Dioxide
4. Methane

Answer: Chlorofluorocarbons

Question: What is the biological community of interacting organisms and physical environment called?

1. Ecosystem
2. Biome
3. Environment
4. Habitat

Answer: Ecosystem

Ecosystem is the geographic area in which plants, animals, and another living organism, as well as the other abiotic and physical components, exist together. Different types of ecosystems include terrestrial, Forest, Desert, Marine ecosystem, etc.

Question: What are the primary decomposers in an ecosystem?

1. Fungi
2. Insects
3. Prokaryotes

1. A and B only
2. A and C only
3. A, B, and C
4. B and C only

Answer: A, B, and C

Decomposers break down dead complex organic matter into organic compounds, carbon dioxide, minerals, etc. These provide nourishment to the plant and enhance soil fertility.

Question: Which of the following is a biodiversity hotspot?

1. Western Ghats
2. Deccan Plateau
3. Thar desert
4. Eastern Ghats

Answer: Western Ghats

Question: What is the rate at which food is accumulated at the trophic level of consumers called?

1. Net primary productivity
2. Gross primary productivity
3. Secondary productivity
4. None of the above

Answer: Secondary Productivity

Question: Which of the following ecosystems have the maximum biomass?

1. Forest Ecosystem
2. Grassland Ecosystem
3. Lake ecosystem
4. Pond Ecosystem

Answer: Forest Ecosystem

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