In ecology we study ecosystems, habitats and communities, in which every organism has its own niche - Leaving Cert Biology - Question 10 - 2010

A habitat is the specific place where an organism lives. It provides all the necessary resources an organism needs to survive, such as food, water, shelter, and mates for reproduction.

A niche refers to the functional role or occupation of an organism within its ecosystem. It encompasses how an organism interacts with the biotic and abiotic factors in its environment, including its role in the food web, its habitat, and its interactions with other species.

One ecosystem I have studied is a freshwater lake. A simple food chain from this ecosystem might be:

Phytoplankton (producers) → Zooplankton (primary consumers) → Small Fish (secondary consumers) → Larger Fish (tertiary consumers).

A trophic level refers to each of the hierarchical levels in an ecosystem, comprising organisms that share the same function in the food chain and the same nutritional relationship to the primary sources of energy. Typically, it can be divided into several levels such as producers, primary consumers, secondary consumers, and tertiary consumers.

In the pyramid of numbers:

• A represents producers (e.g., plants),
• B represents primary consumers (e.g., herbivores),
• C represents secondary consumers (e.g., carnivores).

If all the organisms at C (the secondary consumers) were removed, the population of organisms at B (the primary consumers) would likely increase due to decreased predation. However, this could lead to overgrazing of the producers (level A) since there would be more primary consumers competing for food resources.

The underlined words refer to:

• Habitat destruction: The process by which natural habitats are rendered unable to support the species present, often due to human activities like urbanization and deforestation.
• Over-exploitation: Refers to the unsustainable harvest of natural resources, leading to a decline in species populations.
• Environmental pollution: The contamination of natural resources by substances harmful to living organisms, often resulting from industrial processes and human activities.

One example of a pollutant is plastic waste. Its effect can include harming marine life, as many aquatic organisms ingest plastic, leading to injury or death.

One conservation measure in agriculture is the practice of crop rotation. This helps maintain soil fertility and reduces the need for chemical fertilizers, thus promoting sustainable farming practices.

One problem associated with waste disposal is land pollution, which can result from the accumulation of non-biodegradable waste, leading to detrimental effects on local ecosystems and human health.

Microorganisms play a crucial role in waste management by decomposing organic matter, thus recycling nutrients back into the ecosystem and reducing the volume of waste.