Questions and Answers
Which of the following classes of fungi are known for producing antibiotics?
Dimorphic fungi can exist only as yeasts.
False
What term is used to describe fungi that can cause infections in humans?
Mycoses
The phenomenon where fungi can exist in both yeast and mould forms is known as __________.
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Match the following fungal types with their characteristics:
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Which of these does not typically cause human diseases?
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Protozoa have cell walls.
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What is the role of contractile vacuoles in protozoa?
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What is the main function of myoneme in pond water ciliates?
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All protozoa are harmful to humans.
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What are the two main stages of the protozoan life cycle?
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Entamoeba histolytica causes __________.
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Which of the following protozoa is primarily transmitted through contaminated water from swine feces?
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Match the protozoan with its associated disease:
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Flagellated protozoa move by means of hair-like cilia.
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Non-motile protozoa are classified under the category of __________.
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Which of the following classifications includes organisms that are primarily photosynthetic and eukaryotic?
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Diatoms are large multicellular organisms that dominate the algal community.
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What is the primary function of the stigma found in algae?
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The study of algae is referred to as ______.
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Match the following types of algae with their characteristics:
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Which type of algae is known for its role in causing 'red tides'?
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All algae possess a cell wall that contains cellulose.
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Provide one example of unicellular algae.
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Study Notes
Algae
- Photosynthetic eukaryotic organisms classified in the kingdom Protista.
- Study of algae is known as phycology or algology, conducted by phycologists or algologists.
Unique Parts of Algae
- Pellicle: A thickened cell membrane providing structural support.
- Stigma: A light-sensing organelle, also referred to as an eyespot.
Characteristics of Algae
- Size varies from unicellular microscopic forms (diatoms, dinoflagellates) to large multicellular seaweeds.
- Found in diverse environments including freshwater, saltwater, wet soil, and on wet rocks.
- Energy is primarily produced through photosynthesis, with some species utilizing organic nutrients or surviving with minimal sunlight.
- Most algal cell walls contain cellulose, unique to algae among microorganisms.
- Algae groups include green, golden (or golden brown), brown, and red algae.
Diatoms
- Small unicellular organisms critical to phytoplankton.
- Composed of silicon dioxide, contributing to their refractive properties.
Dinoflagellates
- Microscopic, unicellular, flagellated organisms, often photosynthetic.
- Key contributors to phytoplankton and atmospheric oxygen production, playing significant roles in food chains.
- Some are bioluminescent, known as fire algae, and responsible for red tides.
Green Algae Groups
- Desmids: Unicellular algae that resemble microscopic bananas.
- Spirogyra: Filamentous algae producing long green strands in aquatics.
- Chlamydomonas: unicellular biflagellated algae with a single chloroplast and stigma.
- Volvox: Multicellular colonial algae forming hollow spheres composed of interconnected biflagellated cells, moving in a rolling motion.
Euglena
- Exhibits both algal and protozoan characteristics with photosynthetic capabilities.
Moulds
- Grow as cytoplasmic filaments or hyphae, reproducing through spore formation.
- Commercially significant, especially in producing antibiotics like Penicillium and Cephalosporium.
- Enzymes such as amylase convert starch to glucose, contributing to citric acid production.
Dimorphic Fungi
- Fungi that can exist as either yeast or mould, a phenomenon known as dimorphism.
Fleshy Fungi
- Larger fungi found in forests, including mushrooms and toadstools.
- Constitute a network of filaments (mycelium) that grow in soil or decaying organic matter.
Lichens
- Formed from a symbiotic relationship between alga (often cyanobacterium) and fungus.
- Appear as colored patches on tree trunks and rocks, not associated with human disease.
- Some by-products may possess antibacterial properties.
Slime Moulds
- Found in soil and decaying wood, exhibiting characteristics of both fungi and protozoa.
- Some start as independent amebas, consuming bacteria and fungi.
Medical Significance of Fungi
- Contribute to crop diseases, producing mycotoxins harmful to plants.
- Mycoses: Infections in animals and humans caused by moulds and yeasts, with few being pathogenic to humans.
Protozoa
- Unicellular organisms classified in a separate study field (protozoology), conducted by protozoologists.
- Characterized as free-living, generally lacking cell walls, but may possess flagella or cilia for movement.
- Contractile Vacuole: Pumps excess water out of cells, aiding osmoregulation.
Protozoan Life Cycle
- Trophozoite: Active, motile, and dividing stage.
- Cyst: Dormant, nonmotile survival stage.
Amebae
- Move via pseudopodia (false feet), ingesting food through phagocytosis.
- Entamoeba histolytica: Causes amebic dysentery and extraintestinal abscesses.
Ciliates
- Move using numerous hair-like ciliates, enabling complex motion.
- Balantidum coli: Pathogenic ciliate causing waterborne disease transmitted via contaminated water.
Flagellated Protozoa
- Use whiplike flagella for movement, some being pathogenic.
- Trichomonas vaginalis: Causes trichomoniasis (STD).
- Giardia lamblia: Leads to persistent diarrheal disease.
Non-Motile Protozoa
- Lacking motility structures, classified as sporozoa.
- Plasmodium spp.: Significant pathogens causing malaria in humans.
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Description
This quiz explores the fascinating world of algae, a group of photosynthetic eukaryotic organisms classified in the kingdom Protista. Delve into their unique structures, such as the pellicle and stigma, and learn about the diverse environments they inhabit along with their various types, including diatoms and seaweeds.
