Reproduction in Organisms

Hydra

Step 1: Budding is a type of asexual reproduction where new individuals develop from buds on the parent body. Step 2: When buds are formed on the OUTER surface of the parent body, it is called exogenous budding. Step 3: Hydra is the classic example of exogenous budding – buds develop on the body surface and eventually detach. Step 4: Noctiluca shows endogenous budding where hundreds of buds form inside the cytoplasm. Step 5: Freshwater sponges reproduce by gemmules (internal buds), and Opalina shows plasmotomy. So, Hydra is the correct answer.

Freshwater sponges

Step 1: Gemmules are a special type of internal asexual reproductive structure. Step 2: They are formed in freshwater sponges and some marine sponges. Step 3: Gemmules consist of food-laden archaeocytes surrounded by a hard protective layer. Step 4: During unfavourable conditions, the parent sponge may disintegrate, but gemmules survive and later hatch into new sponges. Step 5: Hydra uses exogenous budding; Planaria uses morphallaxis (regeneration); Star fish shows epimorphosis (regeneration). So, the correct answer is Freshwater sponges.

Abraham Trembley

Step 1: Regeneration is the ability of an organism to regrow lost or damaged body parts. Step 2: This phenomenon was first studied scientifically in Hydra. Step 3: Abraham Trembley was the scientist who first studied regeneration in Hydra in the year 1740. Step 4: Charles Bonnet is associated with the discovery of parthenogenesis in 1745, not regeneration. Step 5: Mendel studied genetics and Pasteur studied microbiology. Therefore, the correct answer is Abraham Trembley.

Morphallaxis

Step 1: Regeneration has two main types – morphallaxis and epimorphosis. Step 2: In morphallaxis, the WHOLE BODY regenerates from even a small fragment of the organism. Step 3: Examples of morphallaxis include Hydra and Planaria. Step 4: Epimorphosis, on the other hand, is the replacement of LOST BODY PARTS (not the entire body). Step 5: Reparative and restorative are subtypes of epimorphosis, not morphallaxis. So, the correct answer is Morphallaxis.