Banu's blog for school students

POLLINATION   The process in which pollen grains from anther of male flower are transferred to stigma of female flower is called pollination. Usually the water, air, wind, insects such as bees acts as agents of pollination. Pollination can happen in two ways:   natural pollination and artificial pollination.  Wind, water, insects and animals such as birds and bats pollinates the flowers and thus acts as natural pollinators. These pollinators transfer the pollen grains from the anther of one flower to stigma of another flower .  TYPES OF NATURAL POLLINATION  There are two types of natural pollination.   Cross pollination: when pollen grains from the anther of one flower is transferred to stigma of another flower of same species, it is called cross pollination. This pollination occurs between flowers of two different  individual plants but of same species.  Self pollination:   When pollen grains are transferred from an anther to the stigma of same flower , it is called self p

ORGANELLES IN A CELL   There are several structures scattered in cytoplasm of a cell. These are called as organelles which performs different functions in cell. Mitochondria is one such organelle which is very important as it is involved in respiration of a cell.  STRUCTURE OF MITOCHONDRIA  Mitochondria ( singular: mitochondria) are small, spherical or cylindrical organelles. The number of mitochondria in a cell depends upon the functions it performs. Cells with heavy energy demands, such as muscle cells, have more mitochondria than other cells. Generally a mitochondrion is 2-8 micron long and about 0.5 micron wide. It is about 150 times smaller than the nucleus. There are about 100 to 150 mitochondria in each cell.  When seen under the compound microscope ,the mitochondria appears oval or cylindrical dots in the cell.  When seen under the electron microscope, the mitochondria seems to have a double membrane wall. Their outer membrane is smooth whereaa inner membrane protrudes into sma