In which stage of the first meiotic division, each chromosome undergoes longitudinal division to give rise to two sister chromatids ? 

• Zygotene

• Diplotene

• Diakinesis

• Pachytene

62.

In biotic community, which of the following can be called protective device ?

• Mimicry

• Symbiosis

• Competition

• Parasitism

Which of the following enzymes is used to join bits of DNA?

• Ligase

• Primase

• Endonuclease

• DNA polymerase

All eukaryotic genes contain two kinds of base sequences. Which of the following plays role in protein synthesis ?

• Introns

• Exons

• Electrons

• Both (a) and (b)

The direction of DNA replication is from :

• amino acid end

• 3' end towards 5' end

• 5' end towards 3' end

• amino terminus to carboxy terminus

In operon concept, regulator gene functions as:

• repressor

• regulator

• inhibitor

• initiator

Mirabilis jalapa is an example of

• complete dominance

• supplementary gene

• incomplete dominance

• complementary gene

Which of the following is dominant character according to Mendel ?

• Dwarf plant and yellow fruit

• Terminal fruit and wrinkled seed

• White testa and yellow pericarp

• Green coloured fruit and rounded seed

Lack of independent assortment of genes A and B in fruit fly Drosophila is due to :

• repulsion

• linkage

• crossing-over

• recombination

When two mutations are located in the same functional unit or in different functional units, then it is confirmed by :

• test cross

• back cross

• reciprocal cross

• complementation test