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Biology for Advanced Level Secondary Schools

Sporozoites to
salivary gland Hepatic cell

Oocyst Mature liver schizont
Merozoites

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Mosquito Erythrocyte
midgut
Ruptured
Ookinate Fusion erythrocyte Erythrocytic schizont

Zygote

Gametocyte

Figure 3.15: The life cycle of a Plasmodium sp.

Adaptations of Plasmodium sp. to its blood, mosquito’s crop, haemocoel and
mode of life salivary glands assures their survival in
Plasmodium sp., a parasite that causes the mentioned parts.
malaria invades the human red blood (e) They have gametocytes, which can
cells as an essential step of its complex resist mosquito’s digestive enzymes,
life cycle; it has the following adaptive and they have adapted to high
features to its mode of life: reproductive rate by schizogony in liver

(a) Presence of a well developed chemotactic cells, repeated schizogony in red blood
responses which enable them to find cells, and sporogony in the mosquito
their way to the liver cells, then to the salivary glands, to ensure their survival.
human red blood cells, gut epithelium,
and eventually, to the salivary glands
of mosquitoes. Exercise 3.5
(b) They have enzymes, which enable them 1. Distinguish between Apicomplexa
to penetrate through the host cells, such and other protoctists.
as liver and red blood cells of humans,
as well as crop and salivary glands of 2. Describe the reproductive cycle of
mosquitoes. a Plasmodium sp.
(c) Plasmodium sp. has an extremely 3. Plasmodium sp. is able to survive
simple structure, which enhances its
sheltered life within the bodies of the in its two different hosts. Justify.
two hosts.

(d) The ability to adjust their osmotic
pressure in relation to the mammalian

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