The layer of cells that secrete enamel of the tooth is

• Dentoblast

• Ameloblast

• Osteoblast

• Odontoblast

The exchange of gases in the alveoli of the lungs takes place by

• Osmosis

• Simple diffusion

• Passive transport

• Active transport

Carbon monoxide is a pollutant because it

• Reacts with oxygen

• Inhibits glycolysis

• Reacts with haemoglobin

• Makes nervous system inactive

4.

Calcitonin is a thyroid hormone which

• Elevates potassium level in the blood

• Lowers calcium level in a blood

• Elevates calcium level in the blood

• Has no effect on calcium

A condition of failure of kidney to form urine is called

• Deamination

• Entropy

• Anuria

• None of these

Solenocytes are the main excretory structures in

• Annelids

• Molluscs

• Echinodermates

• Platyhelminthes

The functional unit of the contractile system in striated muscle is

• Cross Bridge

• Myofibril

• Myofibril

• Z-band

The contraction of gall bladder is due to

• Gastrin

• Secretin

• Cholecystokinin

• Enterogastrone

Sympathetic nervous system induces

• Heartbeat

• Secretion of digestive juice

• Secretion of saliva

• All of the above

The canal system is a characteristic feature of

• Echinoderms

• Helminths

• Coelenterates

• Sponges