The formation of gametophyte, from sporophyte, without spore formation or without meiosis is known as :
apospory
apogamy
parthenogenesis
none of these
A.
apospory
Apospory is the development of gametophyte from a cell of the sporophyte without the intervention of spore. The structure taking part in apospory may be single cell of gametophytic nature, a rhizoid or a gametophyte bearing sex organ or of sporophytic in nature.
Apogamy is a type of plant reproduction in which sporophyte (diploid phase) is produced from the gametophyte (haploid phase) without fertilization. It occurs in some type of ferns.
Parthenogensis is a type of reproduction from an ovum without fertilization. It can operate on either a haploid or a diploid cell.
Acid rain is due to increase in atmospheric concentration of :
Ozone
CO2 and CO
SO3 and CO
SO2 and nitrogen oxide
The true statement about 'green-house effect' is that it is caused by :
CO2 only
SO2 only
CO2 and SO2
CO2, CFC, CH4 and NO2 gases
One of the major difficulties in the biological control of insect pests is the :
practical difficulty of introducing the predator to specific areas
method is less effective as compared with the use of insecticides
predator does not always survive when transferred to a new environment
predator develops a preference to other diets and may itself become a pest
Anemophillous flowers have :
sessile stigma
small and smooth stigma
coloured flower
large and feathery stigma
Photochemical smog formed in congested metropolitan cities mainly consists of:
Hydrocarbons, ozone and SOx
Hydrocarbons, SO2 and CO2
Smoke, peroxyacetyl nitrate and SO2
Ozone, peroxyacetyl nitrate and NOx
The production and maturation of sperm in testes is known as :
oogenesis
sporogenesis
gametogenesis
spermatogenesis