1.1.
Chemoautotroph and photoautrotroph are two
groups autotrophic organisms.
A. a.
By giving one example from each group, compare
the two groups. [3]
b. Heterotrophic organisms can be further
classified into holozoic, saprophytic and parasitic organisms.
i. i. Saprophytic organisms play an important role in
ecology. Explain the statement by using a suitable
example. [8]
ii. Parasites can be classified into obligate and
facultative organisms. Explain these two types of
parasites by giving one example of each. [4]
Answer:
1.a.
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Chemoautotroph
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Photoautotroph
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Done by bacteria
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Done by green plants or organisms which
has the chlorophyll pigment.
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Synthesis organic compounds from carbon
dioxide and water
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Synthesis organic compounds from
inorganic compounds such as carbon dioxide and water.
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Energy – from oxidation of inorganic
substances such as H2S, ammonia and iron
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Energy supply – from the (sun)light.
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1. b.i.
- Saprophytic
organisms can be defined as: organisms that obtain their nutritional needs from
dead and
decaying organic materials
- Cannot synthesize their own food
- secrete enzymes such as amylase,
protease, lipase which digest their food extracellulary
- Absorb the digested products
through the cell surfaces
- examples: Mucor, Rhizipus,
mushroom
- Ecologically important because
they act as a decomposer
- break down the dead organism and
waste product
- the decomposed material which
contains chemicals elements can be reused
(absorbed) by the
saprophytes and other autrotrophs.
b.ii.
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Obligate parasite
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Facultative parasite
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Unable to live independently without
the presence of a host for supply of nutrient
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Able to live independently without the
presence of a host for supply of nutrient
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Unable to reproduce independently
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Able to reproduce independently
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Example: Tapeworm (Taenia solium)
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Example: bootlace fungus (Armillaria mellea)
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Always exist as an obligate parasites
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When under stressful condition; it can
be an obligate parasite
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