Question

A partial parasite is?
A. Cuscuta
B. Cassytha
C. Arceuthobium
D. Viscum

Answer 1

Hint: Parasites are the heterotrophic organisms that derive their nutrition from other living beings. Plants have chlorophyll and perform photosynthesis to produce organic compounds. However, some plants derive the one or other nutritional requirements from their host plants.

Complete answer:
Plants are the autotrophic organisms. They have chlorophyll pigment in their cells which trap the sunlight to facilitate the process of photosynthesis. Plants produce organic substances through the process of photosynthesis.
However, some plants lack chlorophyll pigment and therefore, are unable to perform photosynthesis. These plants cannot synthesize the organic material from the simpler inorganic substances and derive their nutrition from other plants. Cuscuta is an achlorophyllous and parasitic plant and belongs to the family Convolvulaceae. Leaves of the Cuscuta plant lack chlorophyll and are reduced into scalelike structures. Cuscuta is commonly called dodder or amarbel. It lacks roots and has haustoria that serve as sucking roots to withdraw nutrients from the stem of the host plant.
Likewise, Cassytha is a parasite vine and derives food from the host plants only. Arceuthobium is a parasite plant that obtains its nutrition from pine plants.
Viscum is a hemiparasite or partial parasite as it has chlorophyll pigment to perform photosynthesis. It can synthesize the organic substances by photosynthesis but depends on the host plants for water and minerals.

So, the correct answer is D. Viscum.

Note: Viscum is commonly called mistletoe and is a stem parasite. It has slender projections called haustoria that withdraw water and minerals from the xylem of the host plant. It mostly parasitizes oak and walnut plants.