IB DP Biology Topic 4: Ecology : 4.1 Species, communities and ecosystems Question Bank SL Paper 1


Which organism would be classified as a saprotroph?

    1. A single-celled eukaryote that obtains its carbon compounds by photosynthesis and ingestion of other single-celled organisms

    2. A jellyfish that uses the stinging cells in its tentacles to paralyse its prey, which is passed to an internal gastric cavity through a single opening

    3. A fungus that feeds by secretion of digestive enzymes onto its food and absorption of digested material

    4. A dung beetle that feeds on the fecal material left behind by other animals


Ans: C

Endocytosis is the process by which cells absorb molecules by engulfing them. The cell membrane folds inward to form a small pocket, which then pinches off to form a vesicle containing the ingested material.
Examples of saprotrophs include fungi, bacteria, and some types of insects. These organisms play a crucial role in the ecosystem by breaking down dead organic matter and returning nutrients to the soil.


Over time, the hull of a sunken ship may become colonized by a wide range of marine organisms.

What term is used to describe all of the organisms living in and on a sunken ship?

    1. A community

    2. An ecological niche

    3. A population

    4. An ecosystem


Ans: A

The term used to describe all of the organisms living in and on a sunken ship is “shipwreck community”.

A shipwreck community is a term used to describe the diverse group of organisms that inhabit a sunken ship. Sunken ships provide a unique and complex habitat for marine life, as they create a hard substrate in an otherwise soft-sediment environment. Over time, the shipwreck becomes colonized by a variety of organisms, including algae, sponges, corals, and fish. These organisms form a complex community that is adapted to the specific environmental conditions of the shipwreck, including low light levels, strong currents, and limited food resources. The shipwreck community is an important part of the marine ecosystem, as it provides habitat for a diverse range of species and contributes to the overall biodiversity of the ocean.


The image shows a female Golden Orb-weaving spider (Nephila plumipes). They can grow as large as 4 cm and build webs strong enough to trap small birds for food.

Which of the following describe(s) this spider?

I. Primary consumer

II. Heterotroph

III. Arthropod

A. I only

B. I and II only

C. II and III only

D. I, II and III




Golden Orb-weaving spider (Nephila plumipes) belongs to kingdom Arthropoda.

  The Golden Orb-weaving spider (Nephila plumipes) is a heterotroph because it obtains nutrients by consuming other organisms. It is a carnivorous predator that feeds on insects that become trapped in its web. As a spider, it is unable to produce its own food through photosynthesis and must rely on consuming other organisms to obtain the nutrients it needs to survive.

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