Gymnosperm Fertilization The female gametophyte contains several archegonia, where the egg cells originate and develop. Fertilization occurs when pollen grains (male gametophytes) are carried by the wind to the open end of an ovule, which contains the eggs, or female gametophyte.
A catalytic converter is a device used to reduce the emissions from an internal combustion engine (used in most modern day automobiles and vehicles). Not enough oxygen is available to oxidize the carbon fuel in these engines completely into carbon dioxide and water; thus toxic by-products are produced. Catalytic converters are used in exhaust systems to provide a site for the oxidation and reduction of toxic by-products (like nitrogen oxides, carbon monoxide, and hydrocarbons) of fuel into less hazardous substances such as carbon dioxide, water vapor, and nitrogen gas.
Protons and neutrons have approximately the same mass, about 1.67 × 10−24 grams, which scientists define as one atomic mass unit (amu) or one Dalton. Each electron has a negative charge (−1) equal to the positive charge of a proton (+1). Neutrons are uncharged particles found within the nucleus.
