C5: 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

Who defined
adaptation as “the continuous adjustment of internal reaction to external reaction.”

Answer 2

Herbert Spencer

Question 3

adaptations may be ____,
______or _______

Answer 3

morphological, physiological, reproductive

Question 4

Important organs in which degeneration have occurred are

Answer 4

Organs of locomotion
Trophic organs
Nervous system and sense organs

Question 5

The helminthes parasites have attained certain special structures which help them adjust
well within the body of their host. These are:

Answer 5

Shape of the body
Development of protective covering
Development of adhesive organs

Question 6

What are the different forms of adhesive organs found in helminthes parasites?

Answer 6

Acetabulum
Suckers
Hooks
Jaws
Glands

Question 7

In adult flatworms, ____ is present in upper half of the body. It
functions for anchorage

Answer 7

acetabulum

Question 8

_______ are strong organs or attachment found in both trematodes as well as in
cestodes

Answer 8

Suckers

Question 9

In _____, there are two suckers, an anterior sucker
surrounding mouth and a large ventral sucker

Answer 9

Fasciola hepatica,

Question 10

In _______, there are four suckers on the _____.

Answer 10

Taenia solium; scolex

Question 11

In trematodes these unicellular glands, known as _____, are more common in the ______.

Answer 11

cystogenous gland; Cercarial stage

Question 12

The helminthes endoparasites have acquired certain physiological adaptations from the
host environment for them to survive. Some of these physiological adaptations include:

Answer 12

Secretion of antienzymes and mucous
Development of anaerobic mode of respiration
Osmotic pressure adaptability
Chemotaxis

Question 13

movement of a motile cell or organism, or part of one, in a direction
corresponding to a gradient of increasing or decreasing concentration of a particular substance.

Answer 13

Chemotaxis

Question 14

What are the reproductive adaptations of parasites?

Answer 14

Hermaphroditism
Development of cyst wall
Fecundity

Question 15

The organs which are concerned with nutrition are called

Answer 15

trophic organs.

Question 16

• Since the parasite resides in the host body where they live well protected and nourishment readily available, there is no need to move. Hence, the locomotory organelles are completely lost. However, in cases where the larval forms are free living, the locomotory organs in the form of cilia reappears, e.g, Miracidium larva of Fasciola.

Answer 16

Organs of locomotion

Question 17

• As the parasite derives 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).

Answer 17

Trophic organs

Question 18

• The endoparasites live in a well-protected and more or less stable environment inside host’s body in perpetual darkness, there is no need of complex form of nervous system, and consequently the photoreceptor organs (eyes) and other sense organs have completely lost. The central and peripheral nervous system have also reduced considerably as compared to the other free living species of the same phylum.

Answer 18

Nervous system and sense organs

Question 19

The shapes of the body have become _______or _________ or ribbon like which enable them to fit in the space of host’s body where they reside.

Answer 19

round , dorso-ventrally flattened

Question 20

• The integuments of the parasite have lost epidermis and have developed several layered thick protective covering of cuticle.

Answer 20

Development of protective covering

Question 21

The ____is resistant to host’s digestive enzymes, antitoxin and abrasive action of the food and roughage passing through the digestive tract; is permeable to water and also help in the absorption of food

Answer 21

cuticle

Question 22

The nematodes have cylindrical structure, tapering at both ends. Their body is covered by _____ They have a complete digestive system

Answer 22

acellular cuticle.

Question 23

• The endoparasites live in an environment where there is always a danger of being dislodged or swept away along with the hosts body fluid or peristalsis of the alimentary canal. Hence, there is always a demand for certain organs of attachment to keep the parasite in their respective position.

Answer 23

Development of adhesive organs

Question 24

• In order to obtain nutrition from host’s body, most endoparasite live where abundant nutrients are available. But the parasites living inside the gut are always in danger of being digested by the digestive enzymes of the host.

Answer 24

Secretion of antienzymes and mucous

Question 25

a. Strong impermeable _____around the parasite.
b. The parasite stimulates the host gut to secrete huge amount of ________that surrounds the parasite and protects it from the digestive juice of the host.
c. Most of the parasites produce ______which protect them from the gastric juice and digestive enzymes of the host.
d. It has been reported that the___ present in the body wall of the tapeworms neutralizes the acidic effect of the gastric juice.

Answer 25

cuticle
mucous
antienzymes
lime cells

Question 26

• Most of the helminthes endoparasites especially those living inside the gut lumen, live in oxygen deficient environment. At the same time, they possess very low metabolic rate which require very little amount of oxygen.

Answer 26

Development of anaerobic mode of respiration

Question 27

• The parasites maintain osmotic pressure of their body fluid approximately same or slightly less than that of the environment in which they live inside the body of their host. This facilitates them to absorb the nourishment from the general body surface

Answer 27

Osmotic pressure adaptability