How do Organisms Reproduce Test - 7

For Unicellular organisms, cell division or fission leads to the creation of new individuals. Many different patterns of fission have been observed.

Many bacteria and protozoa simply split into two equal halves during cell division. An organism such as Amoeba, the splitting of the two cells during division can take place in any plane.

Other single-celled organisms, such as the malarial parasite, Plasmodium, divide into many daughter cells simultaneously by multiple fission.

Yeast, on the other hand, can put out small buds that separate and grow further.

In Regeneration, Many fully differentiated organisms have the ability to give rise to new individuals organisms from their body parts.

For example, simple animals like Hydra and Planaria can be cut into any number of pieces and each piece grows into a complete organism. This is known as regeneration.

Organisms such as Hydra use regenerative cells for reproduction in the process of budding. In Hydra, a bud develops as an outgrowth due to repeated cell division at one specific site. These buds develop into tiny individuals and when fully mature, detach from the parent body and become new independent individuals.

There are many plants in which parts like the root, stem and leaves develop into new plants under appropriate conditions. The property of vegetative propagation is used in methods such as layering or grafting to grow many plants like sugarcane, roses or grapes for agricultural purpose.

The flower may be unisexual (Papaya, watermelon) when it contains either stamens or pistil or bisexual (Hibiscus, Mustard) when it contains both stamens and pistil.

Pistil is made up of three parts.

(i) Ovary: The swollen bottom part is the ovary.

(ii) Style: The middle elongated part is the style.

(iii) Stigma: The terminal part which may be sticky is the stigma.

The pollen needs to be transferred from the stamen to the stigma. If this transfer of pollen occurs in the same flower. It is referred to as self-pollination.

On the other hand, if the pollen is transferred from one flower to another. It is known as cross-pollination.