Predation is an interaction between two species in which one organism, called the predator, kills and feeds on another organism, called the prey, for food.
Definitions [32]
Define the term Biome.
Biome constitutes a large regional terrestrial unit delimited by a specific climatic zone having a major vegetation zone (plant communities) and the associated fauna.
Definition: Habitat
Habitat is the natural place or environment where an organism lives and grows under suitable conditions.
Define ecological niche.
Niche of an organism can be defined as the total position and function of an individual in its environment.
Definition: Niche
A niche is the functional role of an organism in its environment, including how it uses resources and interacts with other organisms.
Define phenotypic adaptation.
Phenotypic adaptation is a non-genetic trait of an organism, including morphological, physiological, or behavioral changes, that helps it survive in its environment. It is an immediate and reversible response that does not involve changes in the organism’s genetic code.
Define Niche.
Niche describes the position of a species in an environment and also the functional role played by an organism.
Define mutualism.
The type of interaction in which both species are benefitted is called mutualism.
Mutualism refers to an interaction between two different species in which both benefit. (The term symbiosis is frequently used interchangeably with mutualism.)
Define Population.
Organisms of the same kind inhabiting a geographical area constitute the population.
Individuals live in groups in a well-defined geographical area, share or compete for similar resources, and potentially interbreed and thus form a population.
The population is defined as a group of individuals of a species occupying a definite geographic area at a given time.
Define the following term:
Camouflage
Camouflage, also called cryptic colouration, is a defense mechanism or tactic that organisms use to disguise their appearance, usually to blend in with their surroundings. Organisms use camouflage to mask their location, identity, and movement.
Define the following term:
Interspecific competition
Interspecific competition occurs when closely related species compete for limited resources such as food and habitat.
Define stenohaline species.
Species that tolerate narrow range of salinity are called stenohaline species.
Define Community.
A community is an assemblage of populations of different species living in the same area and interacting with one another.
Define the following term:
Commensalism
An interaction in which one species benefits while the other is neither benefited nor harmed is called commensalism.
Define the Stenothermal organisms.
A species or living organism is only capable of living within a narrow temperature range.
Define the following term:
Parasitism
Parasitism is generally defined as a relationship between the two living species in which one organism is benefitted at the expense of the other. The organism that is benefitted is called the parasite, while the one that is harmed is called the host.
Definition: Mortality (Death Rate)
The rate at which individuals die in a population during a given period of time is called mortality.
Definition: Population Growth Rate (r)
The rate of change in population size per individual per unit time is called population growth rate.
Definition: Intrinsic Rate of Growth (rₘ)
The maximum growth rate of a population under ideal conditions with maximum reproduction and minimum mortality is called intrinsic rate of growth.
Definition: Fecundity
The reproductive capacity of a population measured as the number of births during a given period is called fecundity.
Definition: Immigration
The addition of individuals to a population from neighbouring populations is called immigration.
Definition: Emigration
The movement of individuals out of a population to other areas is called emigration.
Definition: Population Growth
The increase in the number of individuals of a species in a given area over a period of time is called population growth.
Definition: Natality (Birth Rate)
The rate at which new individuals are added to a population through reproduction is called natality.
Definition: Mutualism
Mutualism is an interaction between two species in which both are benefited.
Definition: Interspecific Competition
Competition that occurs between individuals of different species for the same limited resources is called interspecific competition.
Definition: Interference Competition
A type of competition in which one organism directly prevents another from accessing a resource is called interference competition.
Definition: Exploitative Competition
A type of competition in which organisms share a resource but one uses it more efficiently than the other is called exploitative competition.
Definition: Intraspecific Competition
Competition that occurs between individuals of the same species for limited resources is called intraspecific competition.
Definition: Competition
The rivalry between two or more organisms for the same limited resource, where the use of the resource by one reduces its availability to the other, is called competition.
Definition: Parasitism
Parasitism is an interaction between two species in which one (known as parasite) obtains its food in ready‑made form from the other living organism (said to be host).
Definition: Predation
Definition: Commensalism
An interspecific relationship in which one organism benefits, while the other is neither benefited nor harmed.
Key Points
Key Points: Population Interactions
- Organisms live in groups forming populations, and different populations together constitute a biotic community.
- Communities show species diversity, interdependence, dominance, and coexistence among different species.
- Communities interacting with their physical environment form an ecosystem with energy flow and nutrient cycling.
- All ecosystems together constitute the biosphere, the highest and most self-sustaining level of biological organization.
Key Points: Major Abiotic Factors
| Abiotic Factor | Key Features | Important Terms | Effect on Organisms |
|---|---|---|---|
| Temperature | Varies from subzero (poles) to ~50°C (deserts); affects enzyme activity and metabolism | Eurythermal, Stenothermal | Determines distribution, activity, and survival |
| Water | Availability controls productivity and distribution of life | Salinity (ppt), Euryhaline, Stenohaline | Causes osmotic challenges; limits habitat range |
| Light | Essential for photosynthesis; varies daily and seasonally | Photoperiod | Influences photosynthesis, migration, reproduction |
| Soil | Depends on climate, weathering, pH, minerals, texture | Percolation, water-holding capacity | Determines vegetation and animal types |
| Organism Response | Ways to cope with abiotic stress | Regulate, Conform, Migrate, Suspend | Ensures survival via homeostasis or adaptation |
Important Questions [22]
- Write a note on desert adaptations.
- Give the adaptations shown by desert animals.
- Define the term natality.
- From the given diagram, identify the type of population growth curve:
- Identify ‘A’ in the given graph of population growth:
- Distinguish between Natality and Mortality.
- Identify the appropriate term for the number of births under ideal conditions: (a) Absolute mortality (b) Realized natality (c) Realized mortality (d) Absolute natality
- Explain the term Emigration.
- Describe steady population with the help of a pyramid.
- Describe diagrammatic representation of age structure showing declining population.
- Construct an age pyramid which reflects an expanding growth status of human population.
- With the help of suitable diagrams, explain how the age structures determine the trend of population.
- Name the type of association: Clownfish and sea anemone
- During Mutualism Typs of Interaction, Both Organisms Are Benefited
- Give the role of VAM related to soil fertility.
- Competition and Mutualism
- Which day is observed as ‘World Environment Day’?
- What is commensalism?
- What is mycorrhiza?
- Pick out the appropriate association representing brood parasitism.
- Complete the following chart regarding population interaction and re-write: Sr. No. Name of interaction Interaction between 1. ? Plasmodium and Man 2. ? Leopard and Lion 3. ? Clownfish and Sea-anemone
- Describe mutualism.
Concepts [14]
- Organisms and the Environment Around
- Habitat
- Niche
- Adaptations and Its Types
- Population
- Population Interactions
- Organisms and Populations
- Population Growth
- Positive Interactions > Mutualism (Symbiosis)
- Negative Interactions > Competition
- Negative Interactions > Parasitism
- Negative Interactions > Predation
- Positive Interactions > Commensalism
- Overview of Organisms and Populations
