CBSE Students who are preparing for upcoming 12th biology exam must practice this class 12 biology solved PYQ 2019. This will be very helpful for students in their exam preparation. Students can understand the exam pattern, question difficulty and also can do self analysis with the help of this PYQ.
We have also given solutions of each question so that student can cross check their answer. Practising Class 12 Biology Previous Year Question papers 2019 before exam can boost confidence in students and students can score better marks in exam. Different set of PYQ has given in this post and CBSE experts have prepared solutions of this PYQ.
Class 12 Biology PYQ 2019 SET 3 with Solutions
Class 12 Biology PYQ 2019 SET 1 with Solution
Class 12 Biology PYQ 2019 SET 3 with Solutions
Class 12 Biology PYQ 2019 SET 1 with Solution
Also Check:
Class 12 Biology PYQ 2025
Class 12 Biology PYQ 2026
CBSE exam is usually held between feb and April every year. And for many students, this exam decides their career specially who want to pursue a career in biology or biotechnology. Practising only chapter is not enough for scoring good marks in exam. Solving Class 12 Biology PYQs is also important.
We hope students found this class 12 biology solved PYQ 2019 helpful for them. Keep learning if you have any questions you can ask in comment section. Also you can also help your friend by sharing this post to them
Important Question of Class 12 Biology PYQ 2019
Question :
How are the members of genus Glomus useful to organic farmers?
SOLUTION :
Glomus belongs to a group of fungi which form mycorrhiza. They form symbiotic association with plants and absorb phosphorous from soil and pass it to the plants. Such associations help the plants in other ways as well – resistance to root borne pathogens, tolerance to salinity and drought. This also results in the overall increase in plant growth and development.
Question
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.
SOLUTION :
The endosperm is triploid in nature which means it will have 48 chromosomes.
The antipodal cells are haploid in nature which means, they will have 8 chromosomes.
OR
Tapetum is the innermost wall layer which provides nourishment to the developing pollen grains. If the tapetum is malfuntioned, proper nourishment to the pollen grains would not be provided and thus would eventually lose their vaibility.
Question
Give reasons why:
(a) DNA cannot pass into a host cell through the cell membrane.
(b) Proteases are added during isolation of DNA for genetic engineering.
(c) Single cloning site is preferred in a vector.
SOLUTION:
(a) We know that cell membranes are made up of phospholipid bilayers which means it has both hydrophillic and hydrophobic regions. DNA being a hydrophillic molecule will face a problem in passing through the hydrophobic regions of the plasma membrane. It is an extremely energy consuming process. This is the reason why host cells are made competent to take up the DNA.
(b) For genetic engineering processes, it is important that the isolated DNA is free of any other biomolecules and is in its purest form.
The DNA is intertwined around basic proteins called histones. During isolation of the DNA, it is treated with proteases (enzymes which degrade proteins) to remove any such proteins which may interfere with the genetic engineering processes.
(c) Cloning sites are short segments of DNA which contain sites for restriction enzymes. Single cloning site is preferred in a vector because multiple cloning sites would result in generation of several fragments thus complicating the process.