Algae and protozoa questions Your textbook and lab manual discuss the difficulty

ID: 47312 • Letter: A

Question

Algae and protozoa questions

Your textbook and lab manual discuss the difficulty microbiologists have in classifying the protists. Briefly describe how the protists were originally classified and what new evidence is creating uncertainty ?n this classic classification scheme. (150 words) How are Algae and Protozoa the same? How are they different from each other? (50 words) How are algae classified? (In other words, what characteristics are used to determine which group an alga belongs in?) Briefly describe some of the key characteristics of Euglenozoa, Chlorophyta, Rhodophyceae, Alveolata, Phaeophyceae and Bacillariophyta. (100 words) How are protozoa classified? Briefly outline the different groups of protozoa and how they are different from each other. (In other words, what characteristics are used to determine which group a protozoan belongs in?) (50-100 words)

Explanation / Answer

Protozoa are motile unicellular eukaryotic organisms. The term protista was first used by Ernst Haeckel in 1866. They were classified into several groups based on their similarities to higher kingdoms. Phylogenetics replaced the classic classification of protists. The protists can be classified into three main groups which include animal-like, plant-like, and fungus-like. This classification is based on three main categories like mode of reproduction, method of nutrition, and motility. The animal-like protists are protozoa, the plant-like protists are algae, and fungus-like protists are slime molds and water molds.

Similarities between Algae and protozoa: Both come under single kingdom protista. Both are composed of eukaryotic cells. Both have a nucleus and they reproduce by mitotic cell division. Both have ability to move. Some of the protozoa and most algae can perform photosynthesis. In contrast, most protozoans and some algae are able to eat food.

Differences

Algae

Protozoa

These are plant-like

These are animal-like

Algae have chlorophyll

Most Protozoa lack chlorophyll

They can produce their own food

These organisms feed themselves by ingesting organic molecules or minute organisms

These are free-floating structures or found attached to rocks

These move with the help of flagella, cilia, or pseudopodia

They do not cause any disease in humans

They cause diseases like malaria

Alga is a very large group. It contains diversity of eukaryotic organisms. Algae are classified based on nature of cell wall, arrangement of flagella, and types of photosynthetic pigments present in cell.

In Chlorophyta: they contain chlorophyll a, b, carotinoids. These live marine water, soil, free-living, and symbiotic.

Rhodophyceae: they contain chlorophyll a, carotinoids, phycobillins. They store food in the form of starch. Cell wall is made of cellulose with agar and carrageenan. They mostly live in marine waters.

Euglenozoa includes both autotrophic and heterotrophic flagellates, free-living and parasitic members. Euglena can move with the help of flagellum and it contains proteinaceous materials in its cell wall.

Alveolata contain small membrane bound cavity which is found beneath the cell membrane. It includes autotrophs, heterotrophs, free-living and parasites.

Bacillariophyta: these contain chlorophyll a, c, carotinoids, xanthophylls. They store food as laminarin or as oil.

Phaeophyceae: these are multicellular with minor degree of specialization. They contain cellulose cell walls and may incorporate calcium carbonate in cell wall. They contain gas bladders.

Protozoa are primarily classified based of how they move. The different groups of protozoa flagellates, amoeboids, sporozoans and ciliates.

Flagellates: they move with the help of flagella. They cause several important diseases like African sleeping sickness.

Amoeboids: the sarcodina group is commonly called amoeboids. These are found in every environment. They contain trophozoite stage. They move by pseudopodia formation.

Sporozoans: these form spores. They live as parasites inside the cells of a host. They cannot move by themselves.

Ciliates: these moves with the help of cilia. These live as ectosymbionts, endosymbionts, obligate or opportunistic parasites.