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IGCSE Biology: Organisms and their environment — Practice Questions & Answers
Master food chains and webs, trophic levels, energy flow, pyramids, the carbon and nitrogen cycles and population growth for IGCSE Biology.
1044 practice questions available for this topic — here are 10 with full answers and explanations.
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Practice questions with answers
1
Multiple choice · Easy
What is the principal source of energy for nearly all ecosystems?
The Sun
The soil
Water
Wind
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Why The Sun is the principal source of energy input to biological systems.
2
Multiple choice · Easy
What is a producer?
An organism that makes its own organic nutrients using sunlight
An organism that eats other animals
An organism that breaks down dead matter
An organism that eats only plants
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Why A producer is an organism that makes its own organic nutrients, usually using energy from sunlight, through photosynthesis.
3
Multiple choice · Easy
What is a herbivore?
An animal that gets its energy by eating plants
An animal that eats other animals
An animal that eats both plants and animals
An organism that makes its own food
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Why A herbivore is an animal that gets its energy by eating plants.
4
Multiple choice · Easy
In the food chain grass -> rabbit -> fox, what is the rabbit?
Primary consumer
Producer
Secondary consumer
Decomposer
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Why The rabbit eats the producer (grass), so it is the primary consumer.
5
Multiple choice · Easy
What is a decomposer?
An organism that gets energy from dead or waste organic material
An animal that hunts and kills prey
An organism that photosynthesises
An animal eaten by a predator
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Why A decomposer is an organism that gets its energy from dead or waste organic material.
6
Multiple choice · Easy
What does an arrow in a food chain represent?
The flow of energy from one organism to the next
The direction the animals move
Which organism is larger
The loss of heat to the surroundings
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Why The arrow shows the direction of energy (and nutrient) flow from the food to the organism that eats it.
7
Multiple choice · Easy
What is the position of an organism in a food chain called?
Trophic level
Niche
Habitat
Population
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Why A trophic level is the position an organism occupies in a food chain or food web.
8
Multiple choice · Easy
What is a population?
A group of organisms of one species living in the same area
All the organisms of all species in an area
The place where an organism lives
All the populations and their environment
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Why A population is a group of organisms of one species living in the same area at the same time.
9
Multiple choice · Medium
Why are food chains rarely longer than four or five trophic levels?
Energy is lost at each level, leaving too little to support more levels
Top predators are too large to be eaten
Producers run out of sunlight
Decomposers remove the top consumers
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Why So much energy is lost between trophic levels that there is too little left to support many further levels.
10
Multiple choice · Medium
In which form is most energy lost between trophic levels in a food chain?
Heat released during respiration
Light reflected from leaves
Energy stored in DNA
Sound made by the animals
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Why Energy is mainly lost as heat from respiration, along with losses in undigested egested material and excretion.
Key terms in Organisms and their environment
Ecology: The scientific study of how living organisms interact with each other and with their non-living surroundings.
Ecosystem: A unit made up of all the living organisms in an area together with the non-living parts of their environment, all interacting with one another.
Environment: The conditions and surroundings in which an organism lives, including both living and non-living factors.
Biotic factor: A living component of an ecosystem, such as predators, prey, food supply or disease-causing organisms.
Abiotic factor: A non-living physical or chemical component of an ecosystem, such as temperature, light, water, pH or soil type.
Habitat: The particular place or type of surroundings where an organism normally lives.
Population: A group of organisms of one species living in the same area at the same time.
Community: All the populations of the different species living and interacting together in the same habitat.
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