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Explain the following terms that are used in ecology: niche, edaphic factor, symbiosis - Leaving Cert Biology - Question 12 - 2007
Question 12
Explain the following terms that are used in ecology: niche, edaphic factor, symbiosis. (b) (i) What is the function of the nitrogen cycle? (ii) What is meant by ni... show full transcript
Worked Solution & Example Answer:Explain the following terms that are used in ecology: niche, edaphic factor, symbiosis - Leaving Cert Biology - Question 12 - 2007
Step 1
Explain the following terms that are used in ecology: niche, edaphic factor, symbiosis.
Answer
A niche refers to the role of an organism within its ecosystem, including its habitat, resource use, and interactions with other organisms. It encompasses how an organism survives, reproduces, and contributes to the energy flow and nutrient cycling in its environment.
An edaphic factor is a component of the soil that influences ecosystem dynamics and includes aspects like soil type, pH, and nutrient content. These factors affect the types of vegetation that can grow, which in turn impacts the organisms that inhabit an ecosystem.
Symbiosis is a close relationship between two different species that benefits at least one of the participants. This relationship can take various forms, including mutualism, where both organisms benefit, commensalism, where one benefits without affecting the other, and parasitism, where one organism benefits at the expense of the other.
Step 2
(i) What is the function of the nitrogen cycle?
Answer
The function of the nitrogen cycle is to convert nitrogen from the atmosphere into a form that can be used by living organisms. It plays a crucial role in maintaining ecosystem health by ensuring the availability of nitrogen, an essential nutrient for the growth of plants and microorganisms.
Step 3
(ii) What is meant by nitrogen fixation?
Answer
Nitrogen fixation is the process by which atmospheric nitrogen (N₂) is converted into ammonia (NH₃) or related compounds. This process can be carried out by certain bacteria, which either live in the soil or form symbiotic relationships with plants, particularly legumes.
Step 4
(iii) Describe, using words and/or labelled diagrams, the events of the nitrogen cycle.
Answer
The nitrogen cycle involves several key steps:
- Nitrogen Fixation: Atmospheric nitrogen is converted into ammonia by nitrogen-fixing bacteria or through lightning strikes.
- Nitrification: Ammonia is then converted into nitrites (NO₂⁻) and then into nitrates (NO₃⁻) by nitrifying bacteria, which plants can readily absorb.
- Assimilation: Plants take up nitrates from the soil to synthesize proteins.
- Ammonification: When organisms die or excrete waste, organic nitrogen is converted back into ammonia by decomposers.
- Denitrification: Finally, denitrifying bacteria convert nitrates back into atmospheric nitrogen, completing the cycle.
Step 5
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Step 7
(iii) If the population of the animals in (ii) declines suggest two possible consequences for the animals in (i).
Answer
If the population of prey declines, two possible consequences for predators include:
- A decrease in food availability, which can lead to starvation and reduced reproductive rates among predator populations.
- Increased competition among predators as they struggle to find enough food.
Step 8
(iv) Give four factors that influence the size of the human population.
Answer
Factors influencing the size of the human population include:
- Birth rate: The number of live births per thousand individuals; higher birth rates lead to population growth.
- Death rate: The number of deaths per thousand individuals; lower death rates can contribute to population growth.
- Healthcare: Access to medical care can reduce mortality rates and improve overall population health.
- Migration: Movement of people into or out of a region can significantly alter population sizes.