Ecosystems Around the World

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Questions and Answers

Define ecosystem.

All the living organisms in a place and the interactions between them and their physical environment.

Define community.

Group of organisms of different species that live in the same habitat.

What is a habitat?

A place where organisms live or shelter for the organisms.

Define population.

Total number of individuals of one species which live in one area. Signup and view all the answers

Which of the following factor does not affect the population size (Select all that apply)

Weather and climate Signup and view all the answers

What is bioaccumulation?

When plants or animals take up a chemical from the environment and do not excrete it, the chemical builds up in the organism over time to a potentially lethal level. Signup and view all the answers

Define biomagnification.

Refers to the sequence of processes that results in higher concentrations of the chemical in organisms at higher levels in the food chain. Signup and view all the answers

What is a food chain?

Flow of energy in an ecosystem is one way process. The sequence of organism through which the energy flows, is known as food chain. Signup and view all the answers

The basic source of energy is sunlight.

True Signup and view all the answers

Which one among these is not an important fact about food chains?

Energy is passed from one trophic level to another Signup and view all the answers

What are the trophic levels in a food chain?

(i) Primary consumers (ii) Secondary consumers (iii) Tertiary consumers (iv) Quaternary consumers Signup and view all the answers

Define decomposers.

Organisms that break down organic matter. Signup and view all the answers

Movement of nutrients is cyclic but flow of energy is unidirectional and non-cyclic.

True Signup and view all the answers

Which of these is NOT a type of food web?

Food web in ocean Signup and view all the answers

What are ecological pyramids?

Graphical representations of the trophic structure of an ecosystem. Signup and view all the answers

Which of these is NOT a type of ecological pyramid?

Pyramid of biodiversity Signup and view all the answers

What does a pyramid of numbers represent?

The graphic representation of numbers of individuals per unit area of various trophic levels. Signup and view all the answers

A pyramid of numbers always depict a pyramid shape.

False Signup and view all the answers

Study Notes

This study covers different ecosystems, varied habitats, bioaccumulation of toxins, biomagnification, and habitat surveys—as detailed in textbook pages 54-70.

Ecosystem Definitions

Ecosystem: All living organisms in a place and their interactions with the physical environment.
Community: A group of different species living in the same habitat.
Habitat: The place where an organism lives or finds shelter.
Population: The total number of individuals of one species living in a specific area.

Factors Affecting Populations

Space: Availability for breeding (can lead to extinction)
Food: Availability (overgrazing can be a factor)
Waste Products: Toxins, insecticides, pesticides, bioaccumulation
Disease
Predators
Physical Environment: Temperature shifts, water availability, pH changes (e.g., due to acid rain)

Food Chain

The flow of energy in an ecosystem is one-way.
A sequence of organisms through which energy flows is called a food chain.
The basic energy source is sunlight.
Organisms obtain energy from the organism in the level below.

Important Aspects of Food Chains

Producers: Plants, make their own food through photosynthesis.
Consumers: Animals, that cannot create their own food and eat plants or other animals for energy.

Trophic Levels in Food Chains

Producers: The base of the food chain.
Consumers:
- Primary consumers: Herbivores (eat plants)
- Secondary consumers: Primarily carnivores (eat herbivores)
- Tertiary consumers: Secondary carnivores (eat other carnivores)
- Quaternary consumers: The top predators at the highest level.
Decomposers: Break down organic matter, returning nutrients to the ecosystem.

Example: Grazing Food Chain

Flower (producer) → Caterpillar (consumer) → Frog (consumer) → Snake (consumer) → Owl (consumer)

Significance of Food Chains

Understanding feeding relationships and interactions between organisms and ecosystems.
Understanding mechanisms of energy flow and matter circulation in ecosystems.
Understanding the movement of toxic substances and biological magnification in ecosystems.

Food Webs

A network of interconnected food chains.
Organisms at various trophic levels are linked by feeding connections.

Key Facts: Food Webs

Trophic levels connect nodes. Arrows represent energy flow (prey to predator).
Lowest trophic level are producers. Highest trophic level are top predators.
Movement of nutrients is cyclical, energy flow is unidirectional and non-cyclic.

Examples of Food Webs

Soil food web, aquatic food web, forest food web, grassland food web, terrestrial and aquatic ecosystem food webs.

Example: Soil Food Web

Includes organisms like nematodes, arthropods, fungi, bacteria, protozoa, earthworms, and other decomposers along with the plants and animals they interact with.

Example: Forest Food Web

Includes organisms like plants, goats, rabbits, mice, jackals, wild cats, owls, snakes, and kites

Example: Aquatic Food Web

Includes organisms such as aquatic plants, fish, insects, frogs, birds, and other organisms found in aquatic ecosystems.

Significance of Food Webs

Distinguishing and defining levels of producers and consumers.
Understanding the foundation of ecosystems and food chains, sustaining life through nourishment and oxygen.
Providing stability to ecosystems.

Energy Flow in Food Chains/Webs

Energy is lost at each level of the food chain.
Loss due to respiration (as heat), movement, finding food.
Warm-blooded animals lose heat in waste products and maintaining body temperature.

Ecological Pyramids

Graphical representations of the trophic structure of an ecosystem.
Shows the feeding positions in a food chain (primary producers, herbivores, primary carnivores, etc.)

Types of Ecological Pyramids

Pyramid of numbers: Represents the number of individuals per unit area at different trophic levels.
- Producers typically form the base—with large numbers.
- Top carnivores have the fewest numbers.
- Can be inverted (e.g., a single tree supporting many insects).
Pyramid of biomass: Represents the biomass (mass of living matter) present per unit area of different trophic levels.
- Producers have the highest biomass at the base.
Pyramid of productivity: Shows the flow of energy through each trophic level over a set time.
- Producers have the greatest productivity.

Decomposers

Organisms that break down organic matter.
Important for recycling nutrients.
Examples include bacteria and fungi.

Breakdown of carbon and nitrogen compounds into simpler forms is a role of the decomposers in an ecosystem

Role of Decomposers

Breaking down complex carbon and nitrogen compounds into simpler forms.
Recycling nutrients.
Cleaning the environment.

Disturbances in Ecosystems

Bioaccumulation: Chemicals accumulate in organisms, potentially reaching lethal levels.
Biomagnification: Chemical concentrations increase at higher trophic levels in a food chain.
Extinction of species: Declining populations disrupt the balance of tropic levels, impacting some levels with excess populations while others suffer.

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Description

Explore the diverse ecosystems around the globe, including habitat analysis, bioaccumulation, and factors affecting populations. This quiz covers essential definitions, the dynamics of food chains, and the implications of environmental changes detailed in textbook pages 54-70.

Ecosystems Around the World - Chapter Overview

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