List of top Biology Questions asked in CBSE CLASS XII

Student to attempt either option (A) or (B):
(A) 
(i) Write two crucial changes, the seed undergoes while reaching maturity that enable them to be in a viable state until the onset of favourable conditions. 
(ii) Name the oldest viable seed excavated from Arctic Tundra as per the records. 
OR (B) 
(i) Pea flower produced seed sets. Give reason. 
(ii) In case of Polyembryony, an embryo ‘P’ develops from a synergid and the embryo ‘Q’ develops from the nucellus. State the ploidy of embryo ‘P’ and ‘Q’.

Student to attempt either option (A) or (B).
(A) Identify the type of pyramid given below and write two identifying features of such a pyramid: 

OR 
(B) 
(i) Construct an ideal pyramid of energy when 10,00,000 Joules of sunlight is available. 
(ii) Mention the energy obtained by the fourth level of this pyramid.} 
 

Given below is a heterogeneous RNA formed during Eukaryotic transcription:
 
How many introns and exons respectively are present in the hnRNA?

In a pedigree chart represents :

Given below is a diagram of T.S. of a monocot seed with parts I, II & III labelled :

Choose the option where parts I, II and III are identified correctly.

Given below are few statements with reference to oogenesis in a human female:

• An unequal division of the primary oocyte forms a large secondary oocyte and a tiny first polar body.
• A couple of thousands of oogonia are formed within each fetal ovary during embryonic development.
• Primary oocytes start meiosis-I but it gets arrested temporarily at prophase-I during fetal development.
• Fertilisation induces the completion of the meiotic division of the secondary oocyte.
• A primary oocyte on meiosis forms an ovum and a polar body.

Choose the option with all true statements from the given options:

Use the given information to select the amino acid attached to the 3′ end of tRNA during the process of translation, if the coding strand of the structural gene being transcribed has the nucleotide sequence ‘TCC’.