The formation of canal system in sponges is due to
reproduction
porous walls
folding of inner walls
gastro- vascular system
C.
folding of inner walls
Canal system is a system of passages connecting various cavities of the animal body as in sponges. It serves the function of food collection, respiration and excretion.
It has less number of cells and thin body wall initially. But when the system gets complicated, the number of flagellated cells increases and the force to draw water current increases. It results in more number of cells and thick body wall. Thick body wall is folded forming regularly arranged in-pushings and out-pushings leading to the formation of canals.
Photorespiration is favoured by
high O2 and low CO2
high CO2 and low O2
high temperature and low O2
high humidity and temperature
The true statement about 'green-house effect' is that it is
caused only by CO2
caused by CO2, CFCs, CH4 and NO2 gases
caused by combination of many gases
none of the above
Cochineal insects have proved very useful for
rodents control
Parthenium control
cactus prevention
Eicchornia prevention
