IB Diploma · Biology B4.2
IB Biology B4.2: Eco. niches — Practice Questions & Answers
IB Biology B4.2 Ecological niches study notes: the niche concept, modes of nutrition, competitive exclusion and resource partitioning.
Here are 10 practice questions with full answers and explanations.
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Practice questions with answers
1
Multiple choice
What is an ecological niche?
- The role of a species in an ecosystem, including biotic and abiotic interactions.
- The physical space an organism occupies.
- The total number of individuals in a population.
- The flow of energy through an ecosystem.
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WhyAn ecological niche is a species' role and its full range of biotic and abiotic interactions in an ecosystem.
2
Multiple choice
What is the main difference between obligate anaerobes and obligate aerobes?
- Obligate anaerobes cannot survive in the presence of oxygen, while obligate aerobes require it.
- Obligate anaerobes require light, while obligate aerobes do not.
- Obligate anaerobes are heterotrophic, while obligate aerobes are autotrophic.
- Obligate anaerobes live in water, while obligate aerobes live on land.
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WhyObligate anaerobes are poisoned by oxygen, whereas obligate aerobes require oxygen for aerobic respiration.
3
Multiple choice
What is holozoic nutrition?
- Food is ingested, digested internally, absorbed, and assimilated.
- Nutrients are absorbed directly from the environment.
- Organic matter is broken down externally.
- Energy is obtained from inorganic chemicals.
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WhyHolozoic nutrition involves ingesting food, digesting it internally, then absorbing and assimilating the products.
4
Multiple choice
Which protist is a well-known example of a mixotroph?
- Euglena.
- Amoeba.
- Paramecium.
- Plasmodium.
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WhyEuglena is a classic mixotroph, photosynthesising in light but also ingesting organic matter when needed.
5
Multiple choice
What is saprotrophic nutrition?
- Decomposers break down dead organic matter externally.
- Organisms consume living prey.
- Organisms produce their own food through photosynthesis.
- Organisms live in symbiotic relationships.
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WhySaprotrophs secrete enzymes onto dead organic matter and absorb the externally digested nutrients.
6
Multiple choice
Which domain of life is known for its metabolic diversity?
- Archaea.
- Bacteria.
- Eukarya.
- Viruses.
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WhyArchaea show remarkable metabolic diversity, exploiting many energy sources and thriving in extreme habitats.
7
Multiple choice
How do archaea obtain energy for ATP production?
- Light, oxidation of inorganic chemicals, or oxidation of carbon compounds.
- Ingestion of organic matter.
- Photosynthesis only.
- Diffusion of nutrients.
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WhyArchaea can be phototrophs, chemolithotrophs or chemoorganotrophs, using light or oxidation of inorganic or organic chemicals.
8
Multiple choice
What can be inferred about an organism's diet from its dentition?
- Whether it is herbivorous, carnivorous, or omnivorous.
- Its lifespan.
- Its habitat.
- Its evolutionary history.
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WhyTooth shape and arrangement reveal whether an animal is herbivorous, carnivorous or omnivorous.
9
Multiple choice
Which family of mammals can be studied to understand the relationship between dentition and diet?
- Hominidae.
- Felidae.
- Canidae.
- Bovidae.
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WhyHominidae dentition is well studied for linking tooth structure to diet across humans and great apes.
10
Multiple choice
What is an adaptation of herbivores for feeding on plants?
- Piercing and chewing mouthparts.
- Sharp claws.
- Venom glands.
- Camouflage.
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WhyMany plant-feeding animals have mouthparts adapted for piercing and chewing tough plant tissue.
Key terms in Eco. niches
Ecological niche: The role of a species in an ecosystem, including the conditions it tolerates and how it obtains resources and interacts with others.
Fundamental niche: The full range of conditions and resources a species could use in the absence of competition.
Realised niche: The narrower range a species actually occupies once competition and other interactions are taken into account.
Autotroph: An organism that synthesises its own organic compounds from inorganic substances, using light or chemical energy.
Heterotroph: An organism that obtains organic compounds from other organisms.
Saprotroph: An organism that secretes digestive enzymes onto dead organic matter and absorbs the products externally.
Mixotroph: An organism that can use both autotrophic and heterotrophic modes of nutrition.
Competitive exclusion: The principle that two species cannot occupy the same niche in the same place indefinitely; one will outcompete the other.
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