Question

Study kingdom protista with special reference of Amoeba (structure, locomotory organ,mode of nutrition, respiration, excretion, reproduction.

Answer 1

Answer:

Kingdom Protista is the hodge-podge category. It contains the protists, or the organisms that do not fit into any of the other categories.

Protista is Greek for the very first. These organisms were traditionally considered the first eukaryotic forms of life, predecessors to the organisms in the plant, animal, and fungus kingdoms. Eukaryotes are organisms whose cells have membrane-bound organelles. This is opposed to prokaryotes, single-celled organisms lacking a nucleus.

Amoebas are small, one-celled animals that can only be seen under a microscope. They don't have a fixed body shape the way you do. Amoebas live all over the world in freshwater ponds, streams, and lakes; salty ocean water; the dirt you walk on; and even in animals.

The mode of nutrition in Amoeba is holozoic and various steps involved in the process of nutrition are:

• Ingestion: Amoeba ingests food with the help of its finger-like extensions, called pseudopodia, when a food particle approaches Amoeba it forms pseudopodia around it and forms a food vacuole inside the Amoeba

• Digestion: Various enzymes from the cytoplasm enter into the food vacuole and break them down into simple soluble molecules

• Absorption: The simple soluble food is absorbed by cytoplasm of Amoeba from food vacuoles through the process of diffusion

• Assimilation: Amoeba cell obtains energy from the absorbed food through respiration and this energy is utilized by Amoeba for its growth and repair of the body

• Egestion: When a considerable amount of undigested food gets collected inside Amoeba, its cell membrane ruptures and throws out the undigested food

Respiration in Amoeba

      We know that amoeba is a unicellular organism which lives in fresh water. This organism does not have a specialized organ to do the process of respiration. So in amoeba respiration takes place through its cell membrane also called plasma membrane. Amoeba gets oxygen gas dissolved in surrounding water through its plasma membrane by the process of diffusion. The oxygen gas diffused inside the body is used up by amoeba. In the body the oxygen gas absorbed is used to break down the complex food material into simple molecules. During these metabolic reactions in the body of amoeba the oxygen gas is converted into carbon dioxide gas. The carbon dioxide gas is also liberated in the surrounding water through the same process of diffusion.