Which one feature is common to leech, cockroach and scorpion

• Nephridia

• Cephalisation

• Ventral nerve cord

• Antenna

Unidirectional transmission of a nerve impulse through nerve fibre is due to the fact that

• nerve fibre is insulated by a medullary sheath

• sodium pump starts operating only at the cyton and then continues into the nerve fibre

• neurotransmitters are released by dendrites and not by axon endings

• neurotransmitters are released by the axon endings and not by dendrites.

The total number of nitrogenous bases in human genome is estimated to be about

• 3.5 million

• 35 thousand

• 35 million

• 3.1 billion.

In which one of the following pairs the two items mean one and the same thing

• Malleus - anvil

• SA node - pacemaker

• Leucocytes - lymphocytes

• Haemophilia - blood cancer

Which one of the following categories of organisms do not evolve oxygen during photosynthesis

• Red algae

• Photosynthetic bacteria

• C₄ plants with Kranz anatomy

• Blue green algae

The bacteria Pseudomonas aeruginosa is useful because of its ability to

• transfer genes from one plant to another

• decompose a variety of organic compounds

• fix atmospheric nitrogen in the soil

• produce a wide variety of antibiotics

7.

Pruning of plants promotes branching because the axillary buds get sensitized to

• ethylene

• gibberellin

• cytokinin

• indole acetic acid.

The sugarcane plant has

• dumb-bell shaped guard cells

• pentamerous flowers

• reticulate venation

• capsular fruits.

In Ulothrix meiosis takes place in

• cells of the filament

• holdfast

• zygote

• zoospores.

In a plant organ which is covered by periderm and in which the stomata are absent, some gaseous exchange still takes place through

• aerenchyma

• trichornes

• pneumatophores

• lenticels.