Latest CBSE Class 12 Biology Marking Scheme and Sample Paper for upcoming board exams 2019 are available for download in PDF format. This exam is scheduled to be held on 15th March 2019. Students of Class 12 having Biology as one of their subjects are advised to go through these important resources for solid preparation of the exam.
Some content from CBSE Class 12 Biology Marking Scheme & Sample Paper: 2019
How many pollen grains and ovules are likely to be formed in the anther and the ovary of an angiosperm bearing 25 microspore mother cells and 25 megaspore mother cells respectively?
Microspore mother cells 25 x 4 =100 pollen grains and from megaspore mother cells 25 ovules respectively. [1/2 + 1/2] a mark each
In case of polyembryony, an embryo A develops from the synergids and the embryo B develops from the nucellus. State the ploidy of embryo A and B.
A-Haploid; B-Diploid. [1/2 + 1/2] a mark each
Give the scientific name of the source organism from which the first antibiotic was produced.
Penicillium notatum. 
The prophase I stage of meiosis plays a vital role in r-DNA formation. Justify with reason.
The prophase I stage of meiosis plays vital role in r-DNA formation because crossing over occurs at this stage which helps in recombination. 
Name the technique by which Gene expression can be controlled with the help of RNA molecule.
RNA interference. 
Diapause is a stage of suspended development in zooplanktons species under unfavourable conditions. 
Define Standing Crop.
Each trophic level has a certain mass of living material at a particular time called as the standing crop. [1/2 + 1/2] a mark each