Chapter – 5 : Environment and It’s Resources | Chapter Solution Class 9

(c) Ecology

Explanation: Ecology is the scientific study of interactions among organisms and their environment.

(b) Autecology

Explanation: Autecology refers to the ecological study of one species in relation to the environment.

(a) Synecology

Explanation: Synecology deals with the ecological study of communities of organisms and their environment.

(c) Community

Explanation: A community includes all the living organisms in a particular ecosystem.

(b) Population

Explanation: Population is a group of organisms of the same species living in a specific area at a given time.

(c) Tansley (1935)

Explanation: The term ecosystem was first introduced by A.G. Tansley in 1935.

(b) Autotrophs

Explanation: Plants produce their own food and are classified as autotrophs.

(b) Consumer

Explanation: Animals depend on others for food and are known as consumers.

(c) Unidirectional

Explanation: Energy in a food chain flows in one direction from producers to consumers to decomposers.

Coal

Explanation: Coal is a fossil fuel and cannot be replenished, hence it is a non-renewable resource.

Snake

Explanation: In many food chains, the snake is a tertiary consumer as it feeds on secondary consumers like rats or frogs.

Unidirectional, reduction

Explanation: The phrase refers to the unidirectional gradual reduction of energy as it flows through the food chain.

Extensive

Explanation: Xerophytic plants have deep and widespread root systems to absorb water from dry environments.

Hump

Explanation: Camels store fat in their hump, which helps them survive long periods without food or water.

False

Explanation: Solar energy is an inexhaustible natural resource as it is continuously available and not depleted by use.

False

Explanation: Natality refers to the birth rate, which increases the population and biomass.

True

Explanation: Pitcher plants are insectivorous and exhibit predatory behavior to trap and digest insects.

True

Explanation: In an ecosystem, energy flows in one direction — from producers to consumers to decomposers — and is not recycled.

Producer

Explanation: All others (Competition, Predation, Parasitism) are types of biotic interactions; Producer is not an interaction but a trophic level.

Autotrophic

Explanation: All others are heterotrophs; only Autotrophic refers to organisms that make their own food.

Coal

Explanation: All others are renewable energy sources; coal is non-renewable.

Biogas

Explanation: Biogas is renewable; all others are non-renewable fossil or nuclear fuels.

Individual

Biosphere

Organisms with their environment

Frog, Fish, Reptiles

Explanation: These are ectothermic animals whose body temperature varies with the environment.

Homeothermic animals

Explanation: Homeothermic (or warm-blooded) animals maintain a constant internal body temperature regardless of external conditions. Examples include birds and mammals.

Plankton

Explanation: Plankton are small or microscopic organisms that float or drift in water, especially in open aquatic environments. They include phytoplankton (plants) and zooplankton (animals).

Hibernation

Explanation: Hibernation is a state of inactivity and metabolic depression in endotherms during winter to conserve energy when food is scarce.

Migration

Explanation: Migration refers to the seasonal or periodic movement of organisms between habitats, usually in response to climate or food availability. It can involve immigration and emigration.

Hydrophyte

Explanation: Hydrophytes are plants adapted to grow in or on water. Examples include lotus, water lily, and hydrilla.

The process by which solar energy is collected by the producers and modified solar energy passes through food chain from the producers to the decomposers at various trophic levels is called an energy flow.

Animals whose body temperature remains constant irrespective of environmental temperature are called endothermic animals.

Animals whose body temperature changes with the environmental temperature are called ectothermic animals.

Population growth is the increase in the number of individuals of a species in a specific area over a period of time due to natality, immigration, and reduced mortality.

Consumers are heterotrophic organisms that cannot produce their own food and depend directly or indirectly on producers for their nutrition.

Example: Herbivores like goats (primary consumers), carnivores like snakes (tertiary consumers).

Heterotrophs are organisms that cannot synthesise their own food and obtain energy by consuming other organisms.

Example: Humans, lions, frogs, and decomposers like fungi and bacteria.

Mutualism is a permanent obligatory association of two organisms or populations where both are physiologically interdependent and get benefit from each other.

Example: Rhizobium bacteria in root nodules of pea plants, and algae Chlorella living in Hydra.

Parasitism is a heterospecific association in which one organism (parasite) survives at the cost of another (host), causing harm to the host.

Example: Ascaris in the human intestine, mosquito feeding on human blood.

The cyclic movement of chemical elements between organisms and the environment in a certain path of the biosphere is called nutrient cycle or biogeochemical cycle.

Example: Carbon cycle, nitrogen cycle.

The principal chemical elements of protoplasm move from environment to organisms and from organisms to environment in a cyclical manner, which is known as nutrient cycle.

Example: Oxygen cycle, phosphorus cycle.

In a definite environment, the living and non-living components live together through a process of interactions to form a stable living system termed as ecosystem. The interactions occur between organisms of biotic communities and their physical environment.

1. Abiotic factors include: sunlight, temperature, water, soil, humidity, minerals, air.
2. Biotic factors include: plants (autotrophs), animals (heterotrophs), and microorganisms like bacteria and fungi (decomposers).

The biosphere is the highest level of ecological organisation. It includes all ecosystems on Earth — land, water, and air — where life exists. All living organisms from different regions interact with their physical environment through cycles (e.g. water cycle, carbon cycle) and processes like energy flow. The biosphere supports life through interconnected systems of producers, consumers, and decomposers across the globe.

An ecosystem is a system formed by the interaction between living organisms and their non-living environment in a particular area. These components interact through nutrient cycles and energy flows.

Examples:

• A pond ecosystem includes water (abiotic), plants, fish, frogs, plankton (biotic).
• A forest ecosystem includes soil, sunlight, rain (abiotic), trees, animals, decomposers (biotic).

An ecosystem is a habitable system formed as a result of interactions between plants, animals, and the abiotic environment. The term was first introduced by Tansley (1935). It consists of biotic components like plants, animals, microbes and abiotic components like air, water, soil, sunlight. These components are interdependent and form a functional unit through energy flow and nutrient cycles.

The term “ecological nation” is not present in the chapter context; likely a misprint or misinterpretation.

Ecological pyramid refers to the graphical representation showing the distribution of energy, biomass, or numbers among trophic levels in a food chain. It is usually upright, with producers at the base and top carnivores at the top. It reflects the gradual reduction of energy at each level due to heat loss, as described by the 10% law.

The nutrient cycle or biogeochemical cycle is the cyclic movement of chemical elements between organisms and the environment.

Examples:

• Carbon cycle: CO₂ is absorbed by plants for photosynthesis, transferred through the food chain, and returned via respiration and decomposition.
• Nitrogen cycle: Atmospheric nitrogen is fixed by bacteria into nitrates, absorbed by plants, passed through food chain, and returned to soil by decomposers.
  These cycles maintain the balance of essential elements in nature.

Energy flow in an ecosystem refers to the transfer of solar energy through trophic levels — from producers to consumers to decomposers.

• Plants trap solar energy via photosynthesis.
• This energy passes to primary consumers (herbivores), then to secondary and tertiary consumers (carnivores).
• Decomposers break down dead organisms and release remaining energy.
  Energy flow is unidirectional and follows the 10% law: only 10% of energy is passed to the next level.

A food chain is the linear transfer of energy from producers to consumers.

Example: Grass → Grasshopper → Frog → Snake → Eagle

A food web is a network of interconnected food chains in an ecosystem where organisms have multiple food sources and consumers. It shows the complex feeding relationships among different organisms.

Food chains and webs demonstrate energy flow and ecological balance in ecosystems.

The nutrient cycle is the continuous movement of chemical elements through living organisms and the environment.

Nitrogen cycle:

• Atmospheric nitrogen (N₂) is fixed by nitrogen-fixing bacteria into nitrates.
• Plants absorb nitrates and convert them into proteins.
• Animals obtain nitrogen by eating plants.
• Decomposers return nitrogen to the soil from dead organisms and wastes.
• Denitrifying bacteria convert nitrates back into nitrogen gas, completing the cycle.