Vectors can be defined as
(a) animals carry the infecting agents from sick person to another healthy person
(b) microorganisms which cause many diseases
(c) infected person
(d) diseased plants

AcademicBiologyNCERTClass 9

Correct Answer(a) animals carry the infecting agents from a sick person to another healthy person


Vector is the pathogen that acts as a vehicle or transport medium to transmit infectious agents to other living organisms. The illnesses caused by vectors are called vector-borne diseases.

Vectors such as mosquitoes, ticks, and fleas are the carrier of causative microbes for various diseases.

For example:

Malaria is a well-known vector-borne disease, caused by the parasitic protozoan, Plasmodium.

During sucking the blood, the female Anopheles mosquito ingests a blood-stage plasmodium and the plasmodium undergoes mating in the gut of the mosquito. Plasmodium begins a cycle of growth and multiplication inside the mosquito. After 10-18 days, a sporozoite (offsprings of plasmodium) migrates to the mosquito’s salivary glands.

When the Anopheles mosquito takes a blood meal (sucks the blood) from another human, anticoagulant saliva is injected together with the sporozoites, which migrate to the liver of the human, hence beginning a new growth cycle.

Updated on 10-Oct-2022 13:32:01