Question

Identify the correct statement/s from the following :
1. Cuscuta is a chlorophyllous endoparasite.
2. The human liverfluke needs only one host to complete its life cycle.
3. The life cycle of endoparasite is more complex due to their extreme specialiasation.
4. During the course of evolution the host bird's eggs have evolved to resemble the eggs of the parasitic bird.

• A. 1, 2, 3
• B. 2, 4
• C. Only 3
• D. 1, 3 and 4

Answer 1

The Correct Option is C

Let's evaluate each statement in detail:

Cuscuta is a chlorophyllous endoparasite:

• This is incorrect. Cuscuta, commonly known as dodder, is an epiparasite, meaning it attaches to the outside of a host plant and absorbs nutrients. It lacks chlorophyll and cannot perform photosynthesis. Therefore, it is a parasitic plant, but not an endoparasite, and it is not chlorophyllous.

The human liver fluke needs only one host to complete its life cycle:

• This is incorrect. The human liver fluke (Fasciola hepatica) requires two hosts to complete its life cycle. The first host is usually a snail, which is an intermediate host, and the second host is typically a mammal (like a human), which is the definitive host. The fluke's larvae are released into water where they infect snails, and then the snails release larvae that infect mammals, including humans.

The life cycle of an endoparasite is more complex due to their extreme specialization:

• This is correct. Endoparasites (parasites living inside the host) exhibit extreme specialization to survive within the host's body. Their life cycles are often more complex because they may involve multiple stages, different hosts, and specialized mechanisms to evade the host's immune system. For example, the human liver fluke (Fasciola hepatica) has a complex life cycle involving different larval stages and host organisms.

During the course of evolution, the host bird's eggs have evolved to resemble the eggs of the parasitic bird:

• This is correct. This phenomenon occurs in brood parasitism. A parasitic bird, like the cuckoo, lays its eggs in the nests of other bird species. Over time, the parasitic bird's eggs have evolved to resemble the eggs of the host species in color and pattern, helping the parasitic bird's eggs go unnoticed, increasing the chances of the host bird incubating them.

The correct statement is only statement 3 because the life cycle of endoparasites is indeed more complex due to their extreme specialization.

So, the correct answer is (C): Only 3

Answer 2

Let's evaluate each statement: 

1. "Cuscuta is a chlorophyllous endoparasite."
   • Cuscuta (dodder) is a parasitic plant that lacks chlorophyll (it is achlorophyllous) and cannot perform photosynthesis. It obtains nutrients from its host plant.
   • It grows on the surface of the host plant, attaching via specialized structures called haustoria. Therefore, it is an ectoparasite, not an endoparasite.
   • This statement is incorrect on two counts (chlorophyllous and endoparasite).
2. "The human liver fluke needs only one host to complete its life cycle."
   • The human liver fluke (like *Fasciola hepatica* or *Clonorchis sinensis*) has a complex life cycle that typically requires two or more hosts. For example, *Fasciola hepatica* requires a mammal (like sheep or humans) as the definitive host and a freshwater snail as the intermediate host.
   • This statement is incorrect.
3. "The life cycle of endoparasite is more complex due to their extreme specialisation."
   • Endoparasites live within the body of their host, a highly specialized environment. They often face challenges related to finding mates, dispersing offspring, and overcoming the host's immune system.
   • These challenges frequently lead to the evolution of very complex life cycles, often involving multiple hosts, specific larval stages, and high reproductive output to ensure transmission. Their anatomy and physiology are also often highly specialized (e.g., loss of certain organs, development of attachment structures).
   • This statement is generally considered correct. The complexity reflects the adaptations needed for a specialized parasitic existence.
4. "During the course of evolution the host bird's eggs have evolved to resemble the eggs of the parasitic bird."
   • This statement describes brood parasitism (e.g., cuckoos laying eggs in other birds' nests).
   • In this co-evolutionary arms race, it is the parasitic bird's eggs that often evolve to mimic the appearance of the host bird's eggs to avoid rejection by the host parent.
   • The host birds, in turn, may evolve better egg discrimination abilities.
   • The statement has the direction of evolution reversed.
   • This statement is incorrect.

Based on the analysis, only statement 3 is correct.

Therefore, the correct option is: Only 3.