Medical Protozoology: Features, Structure

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Questions and Answers

Considering the evolutionary pressures on parasitic protozoa, which adaptation would MOST likely arise in a species exhibiting exclusively asexual reproduction within a single host?

Heightened sensitivity to environmental cues signaling host stress to trigger encystation and dormancy.
Specialized surface ligands for evading antibody recognition while maintaining host cell adhesion. (correct)
Enhanced genetic recombination mechanisms to combat host immune responses.
Increased reliance on complex life cycles involving multiple hosts to maximize transmission opportunities.

Given the diverse mechanisms of protozoan motility, which statement BEST describes the evolutionary trade-offs associated with each method?

Pseudopodia offer rapid bursts of speed useful in high-predation environments, at the cost of energy efficiency.
Apicomplexan gliding motility maximizes speed and minimizes energy consumption but renders them ineffective in complex environments.
Flagella are ideal for traversing mucosal barriers but are energetically inefficient in nutrient-poor environments.
Cilia provide high maneuverability and efficient nutrient uptake, but are susceptible to viscous drag in dense tissues. (correct)

In the context of protozoan nutrition, what functional implications arise from the presence or absence of a cytostome in different parasitic species?

The presence of a cytostome is directly correlated with the complexity of the protozoan's life cycle, indicating a higher degree of host specialization.
The absence of a cytostome necessitates a strictly osmotrophic mode of nutrition, limiting the range of potential host tissues that can be colonized.
Protozoa with cytostomes exhibit greater metabolic flexibility, capable of both phagocytosis and absorption of dissolved nutrients from the extracellular environment. (correct)
Protozoa lacking a cytostome are obligate intracellular parasites, relying exclusively on direct nutrient uptake from the host cell cytoplasm.

How does the differential distribution of chromatin within the nucleus of protozoa contribute to adaptive strategies in the face of varying environmental stresses?

Chromatin distribution affects gene expression, influencing the ability of protozoa to regulate metabolism under stress. (C) Signup and view all the answers

In complex protozoan life cycles involving multiple hosts, what selective advantages are conferred by alternating between asexual and sexual reproduction?

Asexual reproduction in the vertebrate host ensures efficient clonal expansion, while sexual reproduction in the invertebrate vector promotes genetic diversity aiding in adaptation. (D) Signup and view all the answers

Considering the diverse strategies protozoa employ for excretion, which scenario BEST illustrates the adaptive significance of contractile vacuoles?

Contractile vacuoles enable protozoa to regulate cell turgor and expel waste products in freshwater environments. (C) Signup and view all the answers

Given the various modes of protozoan transmission, which strategy would be MOST effective in preventing the spread of a parasite with exclusively transplacental transmission?

Screening pregnant individuals for parasitic infections and providing targeted treatment to prevent vertical transmission. (C) Signup and view all the answers

Considering the classification of protozoa, what are the KEY evolutionary distinctions between Sarcodina and Mastigophora that underlie their diverse parasitic strategies?

Sarcodina utilize pseudopodia for locomotion and phagocytosis, enabling them to thrive as free-living amoebae and opportunistic parasites, whereas Mastigophora use flagella and are more specialized intestinal or urogenital parasites. (B) Signup and view all the answers

In the context of protozoan secretions, what advantage is conferred by the production of digestive and proteolytic enzymes by parasitic species?

Secretion of digestive and proteolytic enzymes allows for extracellular digestion and nutrient acquisition, effectively increasing the range of exploitable hosts and tissues. (B) Signup and view all the answers

Given protozoan secretion capacity, which aspect of protozoan biology is MOST enhanced by secretion of toxic and antigenic substances?

The manipulation of host immune responses to establish chronic infections. (A) Signup and view all the answers

Flashcards

What are Protozoa?

Single-celled eukaryotic microorganisms that perform various functions like reproduction, digestion, and respiration.

What is Ectoplasm?

The outer, homogenous layer of cytoplasm in protozoa, used for locomotion, food engulfment and protection.

What is Endoplasm?

The inner, granular part of cytoplasm containing nucleus, golgi bodies and food vacuoles. Functions include nutrition and reproduction

How do protozoa move?

Protozoa can move via pseudopodia, cilia, or flagella, each facilitating movement in different ways.