Question

1. For each of the following protists, list and describe the major structures. What type of locomotion do you think each protist employs?

A. Euglena

B. Paramecium

C. Giardia

D. Amoeba

E. slime mold

2. Compare the advantages a protist would gain by having a unicellular, filamentous, or colonial form. Explain the advantages of each of the three alternatives.

Answer 1

A. Euglena - Euglena is a single-celled flagellate eukaryotes. it contains the major organelles found in more complex life. This protist is both autotroph and heteroptoph. When acting as a autotroph, the Euglena utilizes its chloroplasts to form sugars by the process of photosynthesis and when acting as a heterotroph, the Euglena surrounds the particle of food and consumes it by the process of phagocytosis.

Structure of Euglena

Flagellum- It is a long and mobile filament, which is used to propel itself in its surroundings.

Reservoir- It is used for storage of nutrients

Stigma- It is a light sensitive-spot, which permits the Euglena to detect light and move towards it in sequence to conduct the process of photosynthesis

Chloroplast- It permits the organism to conduct photosynthesis

Contractile Vacuole- It expels excess water into the reservoir, or else the cell would burst

Pellicle- It is a stiff membrane made of proteins and somewhat flexible. It is used for locomotion when crunching up and down or wriggling

Nucleus- The central organelle which contains DNA and controls the cell's activity.

The movement of euglena is euglenoid movement. It is similar as amoeboid movement.

B) It is a single-celled freshwater animal which has a characteristic slipper-like shape and is covered with cilia.

Structure of a paramecium:

Cilia: minuscule cilia that envelop the paramecium and are used for locomotion.

Contractile vacuole: It is the cavity of the paramecium, which is able to contract.

Food vacuole: It is a cavity of the paramecium, which is responsible for digestion process.

Micronucleus: one of the less important central organelles of a paramecium.

Oral groove: It is a canal of the paramecium, which is used to ingest nutrients.

Gullet: It is the cavity of the pharynx.

Ectoplasm: It is the vitreous superficial layer of a paramecium.

Endoplasm: It is the central part of a paramecium.

Large nucleus: It is the most essential central organelle of a paramecium.

Trochocyst: It is the root of a vibrative cilium of a paramecium.

The locomotion in paramecium ciliated movement. Cilia play a key role in paramecium movement.

C) Giardia - Giardia lamblia lives as a flagellate parasite in the small intestine of man. It causes a disease called giardiasis which causes digestive disturbances.

A bean-shaped sucking disc is present on the ventral surface of the broad or anterior end. Two flagella come out from the posterior end while three other pairs of flagella extend from the lateral and anterolateral surfaces. There are two nuclei with prominent nucleoli. The axostyles are paired.

Two parabasal bodies, which is fused sometimes and lie close to the axostyle and in the posterior third of the body called as cyst. The cysts contain 4-16 nuclei, axostyles, parabasal bodies and fibril.

D. Amoeba - The amoeba is a single celled microscopic organism. It has cytoplasm, nucleus, cell membrane and a variety of inclusions in the cytoplasm and exhibits all the important functions of any living organism.

Cell membrane: The cell membrane is flexible and porous. It permits the amoeba to change shape. The amoeba uses this membrane in the process of breathing. It also controls the entry and exit of substances into and out of the cytoplasm.

Cytoplasm: Cytoplasm is the living substance which contains all the chemical reactions essential for life. There are two types of cytoplasm in the amoeba, the darker cytoplasm toward the interior of the amoeba is known as endoplasm and the clearer cytoplasm that is found near the cell membrane is known as ectoplasm.

Nucleus: A large, disk-shaped nucleus found in the cell. It controls the development and reproduction of the amoeba.

Contractile Vacuole: The contractile vacuole removes excess water to the outside from time to time , therefore the amoeba does not burst. Because the concentration of solutes in the cytoplasm is greater than that in the surrounding fresh water, the water tends to enter the cytoplasm by the process of osmosis via the partially permeable cell membrane.

Food Vacuole: These organisms are then digested and then exits through a structure called a food vacuole.

Digestive Vacuole: This is a cavity responsible for digestion in the amoeba.

Pseudopodium: The amoeba move by stretching its cytoplasm into finger like extensions known as pseudopodia.

The type of locomotion in amoeba is Amoeboid movement.

E) Slime mold - They are basically enormous single cells with thousands of nuclei. They are formed when individual flagellated cells swarm together and fuse. The result is one large bag of cytoplasm with many diploid nuclei. When slime molds get together, the party begins. They form a structure known as a pseudoplasmodium , which moves over logs, bark, and soil at a rate of one inch per day.