The number of hydrogen bonds between adenine and thymine in a DNA molecule is :

• two

• three

• four

• eight

Male cone of Pinus possesses :

• mega sporophylls

• microsporophylls

• anthers

• ligules

C₄ plants, synthesis of sugars/final CO₂ fixation occurs in:

• palisade cells

• spongy cells

• undifferentiated mesophyll cells

• bundle sheath cells

Cook cambium and vascular cambium are :

• parts of secondary xylem and phloem

• parts of pericycle

• lateral meristems

• apical meristems

First natural cytokinin was discovered by :

• Skoog and Miller

• Letham

• Benson and Calvin

• Thimann and Went

Major role of minor elements inside living organisms is to act as :

• binder of cell structure

• constituent of hormone

• building blocks of important amino acids

• cofactor of enzymes

Epipetalous and syngenesious stamens occur in

• Solanaceae

• Brassicaceae

• Fabaceae

• Asteraceae

Which of the following is not vestigial in man ?

• Tail vertebrae

• Nails

• Nictitating membrane

• Vermiform appendix

The chemical used in National Malaria Eradication Programme is :

• 2,4- D

• BHC

• DDT

• Pyrethroid

A eukaryotic gene contains two kinds of base sequences. Which of these plays an important role in protein synthesis?

• Introns

• Exons

• Both 'a' and 'b'

• None of the above