List of top Biology Questions asked in CBSE CLASS XII

What are the major functions of male accessory ducts and glands?
Define spermiogenesis and spermiation.
Name the hormones involved in regulation of spermatogenesis.
What is apomixis and what is its importance?

Distinguish between the following:
(a) Hibernation and Aestivation.
(b) Ectotherms and Endotherms

How is a cancerous cell different from a normal cell?
Try to trace the various components of human evolution (hint: brain size and function skeletal structure dietary preference etc.)
List 10 modern-day animals and using the internet resources link it to a corresponding ancient fossil. Name both.
Practise drawing various animals and plants.
Differentiate between the followings:
(a)Repetitive DNA and Satellite DNA
(b)mRNA and tRNA
(c)Template strand and coding strand
Make a chart(with diagrammatic representation)showing a restriction enzyme, the substrate DNA on which it acts, the site at which it cuts DNA and product it produces.

Collect 5 examples of palindromic DNA sequences by consulting your teacher. Better try to create a palindromic sequence by following base-pair rules.
 

Explain briefly:
(a) PCR
(b) Restriction enzyme and DNA
(c) Chitinase
 

Diagrammatically represent the experimental steps in cloning and expressing an human gene (say the gene for growth hormone) into a bacterium like E. coli?
Outline salient features of carbon cycling in an ecosystem
 
Define ecological pyramids and describe with examples, pyramids of number and biomass.

Briefly describe the following: 

(a) Transcription 

(b) Polymorphism 

(c) Translation 

(d) Bioinformatics
 

Which property of DNA double helix led Watson and Crick to hypothesise semiconservative mode of DNA replication? Explain.
Explain the following terms with example
(a) Co-dominance
(b) Incomplete dominance
How is sex determined in human beings?
Two heterozygous parents are crossed. If the two loci are linked what would be the distribution of phenotypic features in F1 generation for a dihybrid cross?
When a cross in made between tall plants with yellow seeds (TtYy) and tall plant with green seed (TtYy), what proportions of phenotype in the offspring could be expected to be
(a) Tall and green.
(b) Dwarf and green.
Using a Punnett square, work out the distribution of phenotypic features in the first filial generation after a cross between a homozygous female and a heterozygous male for a single locus.
Define and design a test - cross?
Explain the Law of Dominance using a monohybrid cross.