Syllabus Edition

First teaching 2023

First exams 2025

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Ecological Niches (SL IB Biology)

Exam Questions

46 mins11 questions
11 mark

Euglena is an autotroph.

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Identify, from the diagram, the feature which indicates this is an autotrophic organism.

  • Nucleolus

  • Chloroplast

  • Contractile vacuole

  • Mitochondria

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1 mark

Which of the following correctly describe aspects of an ecological niche?

I.
How a species gains its food
II.
Abiotic factors that influence species growth 
III.
Biotic factors that influence species survival
  • I only

  • I and II only

  • II and III only

  • I, II and III

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Saccharomyces cerevisiae is a species of yeast that can survive at a range of oxygen concentrations, including in the absence of oxygen.

Which term describes Saccharomyces cerevisiae?

  • Obligate anaerobe

  • Facultative anaerobe

  • Obligate aerobe

  • Mixotroph

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The table below contains information about the dentition of three extinct hominid species. Note that 'pits' are deeper, larger regions of tooth wear than scratches.

Species Dentition features
Australopithecus africanus

Small canine and incisor teeth and large molar and premolar teeth

Fewer pits on the surface of fossilised teeth than on those of P. robustus
Paranthropus robustus

Large chewing muscles attached to the jaw

Large molar and premolar teeth

Both pits and scratches present on the surface of fossilised teeth

Thick protective tooth enamel
Homo floresiensis

Molar teeth are reduced in size compared to other early hominids

Smaller biting force than that calculated for Australopithecus

Which of the following conclusions can be drawn from the information in the table?

  • Australopithecus africanus consumed meat as an important part of its diet.

  • Paranthropus robustus had more seeds and nuts in its diet than Australopithecus africanus.

  • Homo floresiensis consumed more tough plant material than Australopithecus africanus.

  • Homo floresiensis had a similar diet to that of modern humans.

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Which of the following are adaptations that aid herbivory?

I.
The presence of an enzyme that breaks down cellulose.
II.
Production of toxic secondary compounds.
III.
Proteins that bind to toxins.
  • I only

  • I and II only

  • I and III only

  • II and III only

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Which of the following statements about ecological niches is correct?

  • Competition reduces the size of an ecological niche.

  • An ecological niche can be shared between two similar species.

  • Competition for a niche always results in local extinction for one species.

  • A realised niche is larger than a fundamental niche.

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The Ghost Orchid (Epipogium aphyllum) is a rare plant species which lacks leaves or chlorophyll. The plant has formed a symbiotic relationship with a fungus in order to obtain the nutrition it requires. The growth of the fungus is slowed as a result of the relationship.

Which of the following rows correctly describes E.aphyllum?

  Heterotroph Autotroph Parasite Saprotroph
A X X
B X X
C X
D X X

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