'Gymnosperm' have how many species?
1000
900
640
300
C.
640
Gymnosperms are seed bearing vascular plants, such as cycads, ginkgo, yews and conifers in which the ovules or seeds are not enclosed in an ovary.
About 70 Genera and 730 species of gymnosperms exist. Therefore, option 'c' is the nearest to 730 and should be considered correct.
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
The formation of canal system in sponges is due to
reproduction
porous walls
folding of inner walls
gastro- vascular system
