CBSE Class 12 Biology Question Paper 2019 Set N

CBSE Class 12 Biology Question Paper 2019 Set N. Students can download the last year board exams question papers using the link below. Free download of examination question papers with solutions. Last 10 year question papers should be practised to get better marks in examinations.

SECTION A

1. Name the disorder in humans with the following karyotype :

(a) 22 pairs of autosomes + XO

(b) 22 pairs of autosomes + 21^st chromosome + XY

2. How do lactic acid bacteria (LAB) initiate setting of milk into curd ?

3. The diploid number of chromosomes in an angiospermic plant is 16. What will be the number of chromosomes in its endosperm and antipodal cells ?

OR

State the reason why pollen grains lose their viability when the tapetum in the anther is malfunctioning.

4. What do ‘X’ and ‘Y’ represent in the transcription unit of the DNA molecule shown ?

5. Biotechnological techniques can help to diagnose the pathogen much before the symptoms of the disease appear in the patient. Suggest any two such techniques.

OR

Mention the form in which inactive protein toxin is produced by Bacillus thuringiensis. How does it get activated in the pest body to kill it ?

SECTION B

6. Write the scientific name of the tropical sugar cane variety of South India. Why was the need felt to cross it with the sugar cane variety of North India ?

7. (a) How will you measure population density of fish in a lake ? (b) In a pond there are 100 frogs. 20 more were born in a year. 

Calculate the birth rate of this population.

OR

Draw a ‘‘stable’’ human age pyramid. Comment on the population growth rate that is depicted by it. 

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