Biology 12th cbse

QUESTION1: 

Which of the following is widely used as a successful biofertiliser in Indian rice field ?

ANS:Azolla pinnata

QUESTION2: 

 Which of the following options incldes biofertilscrs ?

ANS:Nostoc, Oscillatoria

QUESTION3: 

 Nitrogen fixation in root nodules of Alnus is brought about by

ANS:.Frankia

QUESTION4: 

The vitamin whose content increases following the conversion of milk into curd by lactic acid bacteria is

ANS:Vitamin B12

QUESTION5: 

Wastewater treatment generates a large quantity of sludge, which can be treated by

ANS:anaerobic digesters

QUESTION6: 

Methanogenic bacteria are not found in

ANS:activated sludge

QUESTION7: 

The primary treatment of wastewater involves the removal of

ANS:Stable particles

QUESTION8: 

 Which one of the following is not a nitrogen-fixing organism ?

ANS: Pseudomonas

QUESTION9: 

The inoculum is added to the fresh milk in order to convert milk into curd, the term ‘inoculum’ here refers to

ANS:a starter containing milions of LAB

QUESTION10: 

The chemical substances produced by some microbes which can kill or retard the growth of other microbes are called

ANS:Antibiotics

QUESTION11: 

Antibiotics are obtained from

ANS:All of these

QUESTION12: 

Biofertilisers are

ANS:some bacteria and cyanobacteria

QUESTION13: 

The symbiotic association between fungi and roots of higher plants is referred to as

ANS:mycorrhiza

QUESTION14: 

 Cyanobacteria are

ANS:Autotrophs

QUESTION15: 

Is the first step of sewage treatment.

ANS: Sedimentation