Ecological niche & conditions for survival
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Question
What is an ecological niche?
Answer
An organism's **role** in its ecosystem: the **abiotic conditions** it tolerates, **how it obtains food/energy**, and its **interactions** with other species.
Question
What is the difference between a habitat and a niche?
Answer
The **habitat** is **where** an organism lives (its address); the **niche** is **what it does** there and the conditions it needs (its job).
Question
Define an abiotic factor.
Answer
A **non-living**, physical or chemical feature of the environment (e.g. temperature, light, pH, dissolved oxygen, salinity).
Question
Define a biotic factor.
Answer
A condition created by **other living organisms** (e.g. food supply, predators, competitors, disease).
Question
What is the range of tolerance?
Answer
The span of an abiotic factor an organism can survive in — best in the **optimum range**, stressed in the **zones of stress**, and **absent** beyond the **limits of tolerance**.
Question
What happens to an organism in its optimum range?
Answer
It is **most abundant and active** — the conditions are ideal for it.
Question
What happens beyond an organism's limits of tolerance?
Answer
It is **absent** — it cannot survive there at all.
Question
What is an obligate aerobe?
Answer
An organism that **must have oxygen** to survive, because it relies on **aerobic respiration** to release energy.
Question
What is an obligate anaerobe?
Answer
An organism for which **oxygen is toxic**; it survives **only where oxygen is absent** (e.g. waterlogged mud).
Question
Why does an obligate aerobe need oxygen?
Answer
It must carry out **aerobic respiration** to release enough energy, and aerobic respiration **requires oxygen**.
Question
Name one condition for survival for an aquatic organism, with a reason.
Answer
**Dissolved oxygen** — needed for aerobic respiration (for an obligate aerobe).
Question
If a place lacks even one required condition, what happens to the organism?
Answer
It is **absent** there, however good the other conditions are.
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Topic 2.9 hub
Adaptation to environment
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