Statement I: Cuscuta, a parasitic plant that is commonly found growing on hedge plants, has lost its chlorophyll and leaves in the course of evolution.
Statement II: Parasites that feed on the external surface of the host organism are called ectoparasites.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Both statements I and II are correct.
A parasite lives on or in another organism, called the host, and takes food from it. Parasites are grouped by where they live: ectoparasites feed on the outer surface of the host, and endoparasites live inside the host’s body.
Statement I: Cuscuta, a parasitic plant that is commonly found growing on hedge plants, has lost its chlorophyll and leaves in the course of evolution. — True. Cuscuta takes all its food from the host plant. It no longer needs to make food, so over time it has lost its chlorophyll and leaves.
Statement II: Parasites that feed on the external surface of the host organism are called ectoparasites. — True. This is the definition of ectoparasites. Lice on humans and ticks on dogs are common examples. Cuscuta is also an ectoparasite, as it grows over the outer surface of its host.
NCERT Extract:
Population Interactions – “… Parasites that feed on the external surface of the host organism are called ectoparasites. The most familiar examples of this group are the lice on humans and ticks on dogs. Many marine fish are infested with ectoparasitic copepods. Cuscuta, a parasitic plant that is commonly found growing on hedge plants, has lost its chlorophyll and leaves in the course of evolution. It derives its nutrition from the host plant which it parasitises.”