WAEC Biology Questions On Modes Of Heterotrophic Nutrition

Summary of the Topic:

Heterotrophic nutrition refers to the mode of nutrition in which organisms obtain their food by consuming other organisms or organic matter, as they cannot synthesize their own food. This encompasses various modes, including:

Holozoic Nutrition: Involves ingestion, digestion, absorption, assimilation, and egestion of solid food particles. Common in animals and protozoans.
Parasitic Nutrition: Organisms derive nutrients from a host organism, often causing harm to the host.
Saprophytic Nutrition: Involves feeding on dead and decaying organic matter, commonly seen in fungi and some bacteria.
Symbiotic Nutrition: Two organisms live in close association, with at least one benefiting from the relationship.

Understanding these modes is crucial for comprehending how different organisms obtain and utilize nutrients.

Key Concepts Explained:

1. Holozoic Nutrition:
Organisms ingest solid food, which is then digested internally. This mode includes herbivores, carnivores, omnivores, and detritivores.
Examples: Humans, Amoeba, Dogs.

2. Parasitic Nutrition:
Parasites live on or inside a host organism, obtaining nutrients at the host’s expense.
Examples: Tapeworms, Plasmodium, Lice.

3. Saprophytic Nutrition:
Saprophytes feed on dead and decaying organic matter, secreting enzymes to break it down externally before absorption.
Examples: Rhizopus, Mushrooms, Mucor.

4. Symbiotic Nutrition:
Two organisms live in close association, with at least one benefiting. This can be mutualistic (both benefit) or commensalistic (one benefits, the other is unaffected).
Examples: Lichens (algae and fungi), Rhizobium in legume roots.

Example WAEC-Style Questions (With Explanations):

Q1: Which of the following is not an example of a heterotrophic mode of nutrition?
A. Symbiosis
B. Parasitism
C. Commensalism
D. Holophytism
Answer: D. Holophytism
Explanation: Holophytism refers to autotrophic nutrition, where organisms synthesize their own food, unlike heterotrophic modes.

Q2: An organism is considered a heterotroph when it:
A. Feeds on inorganic food
B. Feeds on already manufactured food
C. Fixes atmospheric nitrogen
D. Respires anaerobically
Answer: B. Feeds on already manufactured food
Explanation: Heterotrophs rely on organic substances produced by other organisms for nutrition.

Q3: Which of the following organisms feeds both autotrophically and heterotrophically?
A. Hydra
B. Paramecium
C. Mucor
D. Euglena
Answer: D. Euglena
Explanation: Euglena can photosynthesize (autotrophic) and also ingest food particles (heterotrophic), exhibiting mixotrophic nutrition.

Q4: Organisms that feed on dead, decaying tissues of other organisms are known as:
A. Parasites
B. Autotrophs
C. Heterotrophs
D. Saprophytes
Answer: D. Saprophytes
Explanation: Saprophytes obtain nutrients by decomposing dead organic matter.

Q5: The capturing and digestion of insects by a pitcher plant is a special form of nutrition that is:
A. Chemosynthetic
B. Saprophytic
C. Heterotrophic
D. Autotrophic
Answer: C. Heterotrophic
Explanation: Although plants are generally autotrophic, carnivorous plants like the pitcher plant supplement their nutrition by digesting insects, a heterotrophic behavior.

Study Tips:

Create Comparative Tables: List different modes of heterotrophic nutrition alongside their characteristics and examples to aid memorization.
Use Mnemonics: Develop memory aids to remember the types and features of each nutritional mode.
Diagrammatic Representations: Draw diagrams illustrating examples of organisms exhibiting each mode of nutrition.
Practice Past Questions: Regularly solve past WAEC questions to familiarize yourself with the exam pattern and question styles.
Group Discussions: Engage in discussions with peers to reinforce understanding and gain different perspectives.

Conclusion:

A comprehensive understanding of heterotrophic nutrition modes is essential for mastering biology concepts related to organismal feeding strategies. To reinforce your learning, proceed to the WAEC past questions provided below, which offer practical application of the concepts discussed.

OBJECTIVES

1. Analysis of the gut content of an animal showed that it contained small pieces of bone, seeds, roughage and insects. The animal is likely to be a/an

A. carnivore.

B. herbivore

C. insectivore.

D. omnivore.

2. A beaker of pond water containing few specimens of Euglena was placed in a dark room for two weeks. At the end of this period, the specimens of Euglena were still alive because they were

A. able to carry out holozoic nutrition.

B. able to carry out photosynthesis using carbon dioxide in the pond water.

C. better adapted to life in darkness than to life in light.

D. not avercrowded.

3. The organism that can carry out both autotrophic and heterotrophic modes of nutrition is

A. Chlamydomonas.

B. Eudorina.

C. Euglena:

D. Spirogyra.

4. Which of the following protozoans feeds parasitically?

A. Paramecium.

B. Chiamydomonas.

C. Plasmodium.

D. Euglena.

5. Which of the following features of the tadpole indicates that the animal is herbivorous? Possession of

A. operculum.

B. muscular tail.

C. long coiled intestine,

D. Internal gills.

6. An example of a saprophytic relationship is a/an

A. vulture feeding on decaying meat.

B. mushroom growing on decaying vegetation.

C. boy eating stale bread.

D. earthworm feeding on decaying vegetation.

7. Which of the following groups consists of heterotrophs?

A, Mucor, chlamydomonas and Euglena.

B. Spirogyra, Mucor and Mushroom.

C. Man, Mucor and Mushroom.

D. Man, Maize and Cowpea.

8. Which of the following is not an example of a heterotrophic mode of nutrition?

A. Symbiosis.

B. Parasitism.

C. Commensalism.

D. Holophytism.

9. An organism is considered a heterotroph when it

A. feeds on inorganic food.

B. feeds on already manufactured food.

C. fixes atmospheric nitrogen.

D. respires anaerobically.

10. Which of the following organisms feeds both autotrophically and heterotrophically?

A. Hydra.

B. Paramecium.

C. Mucor.

D. Euglena.

11. The mode of nutrition which describes feeding habit in animals is

A. autotrophic.

B. holazoic.

C. holophytic

D. saprophytic.

12. The type of nutrition shown by Spirogyra is

A. symbiosis.

B. holophytic.

C. holozaic

D. chemosynthetic.

13. Which of the following plants is a carnivore?

A. Desmodium.

B. Sundew.

C. Mushroom.

D. Platycerium.

14. Hydra feeds by

A. digesting its food extra cellularly.

B. absorbing food digested by other organisms.

C. symbiotic association.

D. masticating the food particles.

15. The following organisms are examples of carnivorous plants except

A. Glorioso.

B. Venus flytrap.

C. Pitcher plant.

D. Utriculario.

16. Organisms that feed on dead, decaying tissues of other organisms are known as

A. parasites.

B autotrophs.

C. heterotrophs.

D. saprophytes.

17. The type of nutrition in which organisms take in solid organic materials into their body is

A. holoroic.

B. symbiotic.

C. saprophytic.

D. parasitic.

18. The capturing and digestion of insects by a pitcher plant is a special form of nutrition that is

A. chemosynthetic.

B. saprophytic.

C.heterotrophic.

D. autotrophic.

THEORY

1. Describe briefly the mode of feeding in tapeworms

2. Name three organisms that carry out holozoic mode of nutrition

3. The table below indicates different methods by which organisms obtain food. Place the following Organisms under the headings in the table below: Human, Mushroom, Venue flytrap, Waterleaf plant, Tapeworm, Elephant grass, Housefly, Lichen, Spirogyra, Rhizopus.

Mode of Nutrition