Biology Test - 15

Parthenogenesis is a process of reproduction where the ovum is unfertilized. In case of bees the eggs are haploid which subsequently makes the male bee haploid. It is a type of asexual reproduction. This type of reproduction takes place in lower plants like aphids.

Fertilization is the process of fusion of the male and female gamete to form an egg or a zygote. It is a type of sexual reproduction. Formation of a diploid cell from 2 haploid cells.

The pollen grains carry the male organ. Mostly the male organs are the motile gamete while the female organ is stationary. It is necessary for the male organs to be small and light for easy propagation by the environmental agents.

Zygote develops into an embryo. It happens through a series of cell division and cell differentiation. In case of flowering plants, the zygote develops into an embryo and the ovule develops into a seed.

In suckers the lateral branches arise from basal and underground portions of the main stem. They grow horizontally underground and the leafy shots arise from the soil. For example, bananas.

Conidia are non-motile fungal spores that are produced singly or in chains by constriction of tips of conidiophores and are dispersed by wind. Zoospores are motile fungal spores. Gemmules are reproductive structures of sponges and nodes are just a site on the stem from where the new plant arises in rhizomes (vegetative propagation).

Ovaries develop into fruits which further develop a thick wall covering called the pericarp. The major function of the pericarp is protection. After fertilization all flower parts wither and fall off.

Plants pollinated by wind produce a large (maybe billions) amount of pollen grains into the air so that they hit the target on other plants. Many crop plants like wheat are wind pollinated.

In plants pollinated by the wind, flowers are small and inconspicuous. The pollen grains are made light weight and unwettable due to the presence of a mucilage covering. The water current acts as a pollen vector

Adventitious buds arise from the margin of the leaves in Bryophyllum. Those buds give rise to new plants that fall of when they are capable enough to grow on their own.

This unique ability has been exploited by the gardeners and farmers.