Category: Biology

Senescence Senescence can be defined as the collective, progressive and degenerative processes that ultimately lead to termination of functional activities of an organ or organism.  It may also be …

Seed Dormancy Seeds germinate as soon as they undergo maturation and are provided with suitable conditions for germination, as in bean, maize, peas etc.,.  In some species, seeds germinate …

Germination of seeds In a dry seed the embryo is alive and all the vital activities continue in the cells but, at a slow rate. Thus the embryo remains …

The Seed Seed may be defined as the ripened ovule.  The gymnosperms and angiosperms are characterized by the presence of seeds.  In gymnosperms, the megasporophylls do not form ovary, …

Post fertilization changes The process of fertilization and triple fusion result in the formation of a diploid zygote and a triploid primary endosperm nucleus respectively. Diploid zygote is the …

Fertilization The fusion of nuclei of male and female gametes is called fertilization.  It was discovered by Strasburger in the year 1884.  In seed plants, fertilization takes place in …

The contrivances for cross pollination The special devices or adaptations which favour cross pollination are as follows: Dicliny or unisexuality: Flowers are unisexual.  The plants may be monoecious or …

Cross pollination Cross pollination is the transfer of pollen grains from the anther of one flower to the stigma of a genetically different flower.  This process is also called …

Pollination Pollination is the transfer of pollen grains from the anther to the stigma.  As the pollen grains are immobile, they require an external agent to reach the stigma.  …

Megasporogenesis Megasporogenesis is the process of formation of megaspores from the megaspore mother cell.  In the hypodermal region of nucellus towards the micropylar end develops a primary archesporial cell.  …