CameraIcon
CameraIcon
SearchIcon
MyQuestionIcon
MyQuestionIcon
1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

Assertion :DDT has now become almost ineffective against mosquitoes. Reason: Introduction of DDT brought a change in the gene frequency with a shift from DDT-sensitive to DDT-resistant mosquitoes.

A
Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
B
Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
Assertion is correct but Reason is incorrect.
No worries! We‘ve got your back. Try BYJU‘S free classes today!
D
Assertion is incorrect but Reason is correct.
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
Mosquitoes are known to be the vectors of diseases like malaria and dengue fever caused by Plasmodium and Dengue virus. Earlier the mosquito-population had more DDT-sensitive but less DDT-resistant mosquitoes. When DDT was not being used, the DDT-resistant remained dominated by DDT-sensitive mosquitoes. But when the use of DDT as an insecticide started (introduced in 1940s), DDT-resistant mosquitoes had a competitive advantage over their counterparts. Their DDT-resistant property spread over more and more members of the population so now the mosquito population is dominated by DDT-resistant ones. It is also an example of directional selection. Thus according to principle of Natural Selection, chemical insecticides would remain useful only for a limited time. So, both Assertion and Reason are correct and Reason is the correct explanation for Assertion.

flag
Suggest Corrections
thumbs-up
0
similar_icon
Similar questions
View More
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
Impact of Housefly
BIOLOGY
Watch in App
Join BYJU'S Learning Program
CrossIcon