Chapter 5 ADAPTATIONS TO PARASITIC MODE OF LIFE

Question 1

________ is a dynamic process of adjustment with the new environment for establishment, self-regulation, self-preservation and race continuation.

Answer 1

adaptation

Question 2

Morphological Adaptations

Answer 2

1. Degeneration of organs - complete or partial degeneration or loss of organs
2. Attainment of new organs - attained certain special structures which help them adjust well within the body of their host

Question 3

Degeneration of organs

Answer 3

1. Organs of locomotion - they live well protected and nourishment readily available
2. Trophic organs - fully digested or partially digested nutrition from the host’s body, the alimentary canal has either totally disappeared (e.g. Taenia solium) or exhibit fair degree of degeneration (e.g. Fasciola, Ascaris)
3. Nervous system and sense organs - well-protected and more or less stable environment inside
   host’s body in perpetual darkness,

Question 4

Attainment of new organs

Answer 4

1.Shape of the body- well-protected and more or less stable environment inside
host’s body in perpetual darkness,
1. Development of protective covering: layered thick protective covering of cuticle; resistant to host’s digestive enzymes, permeable to water; protective spines have developed
1. Development of adhesive organs - danger of being dislodged or swept away

Question 5

Different forms of adhesive organs found in helminthes

Answer 5

1. Acetabulum - upper half of the bodyl anchorage
2. Suckers - strong organs/ attachment found in both trematodes, cestodes
3. Hooks - anterior end of the body of cestodes, trematodes-as an organ of attachment
4. Jaws - in nematodes, chitinous jaws inside mouth to anchor on the gut wall
5. Glands - unicellular secretory glands have developed in the vicinity of the mouth-anchorage in favorable habitat, aid in food supply

Question 6

Physiological adaptations

Answer 6

1. Secretion of antienzymes and mucous: impermeable cuticle, mucous, antienzymes, lime cells
2. Development of anaerobic mode of respiration: obtain energy by fermentation of glycogen
3. Osmotic Pressure adaptability: prevents the disturbing exchange of water
4. Chemotaxis - movement of a motile cell/ organism, or part of one, in a direction corresponding to a gradient of increasing or decreasing concentration of a particular substance

Question 7

Reproductive Adaptation/ Elaboration of reproductive organs

Answer 7

1. Hermaphroditism
2. Development of cyst wall - resistant wall
3. Fecundity - producing large number of eggs
4. Complexity of life cycle - presence of intermediate host minimizes the exposure period to the external environment