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Questions and Answers
In an area where ______ are harvested for human consumption, the beach will be closed during a red tide.
In an area where ______ are harvested for human consumption, the beach will be closed during a red tide.
clams
Cilia are often used for ______ and feeding.
Cilia are often used for ______ and feeding.
swimming
Ciliates possess ______ type of nuclei: micro and macronucleus.
Ciliates possess ______ type of nuclei: micro and macronucleus.
two
Ciliates possess a ______ contractile vacuole.
Ciliates possess a ______ contractile vacuole.
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The shape of a ciliate is maintained by the complex ______.
The shape of a ciliate is maintained by the complex ______.
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The ______ is responsible for producing RNAs and proteins for daily functions.
The ______ is responsible for producing RNAs and proteins for daily functions.
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During asexual reproduction, the macronucleus divides into ______ pieces.
During asexual reproduction, the macronucleus divides into ______ pieces.
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During conjugation, the haploid micronuclei resulting from ______ division function as gametes.
During conjugation, the haploid micronuclei resulting from ______ division function as gametes.
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The pseudopodia are used for movement and ______ in Amoebas.
The pseudopodia are used for movement and ______ in Amoebas.
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Most amoebas are heterotrophs that actively seek and engulf bacteria and other protists by ______.
Most amoebas are heterotrophs that actively seek and engulf bacteria and other protists by ______.
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Lobopodia are ______ and broad cell processes containing ectoplasm and endoplasm.
Lobopodia are ______ and broad cell processes containing ectoplasm and endoplasm.
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Some members of amoebas referred to as ______ amoebas lack a test or other supporting structures.
Some members of amoebas referred to as ______ amoebas lack a test or other supporting structures.
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Filopodia are ______-like and contain ectoplasm only.
Filopodia are ______-like and contain ectoplasm only.
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Reticulopodia are ______-like series of cell extensions.
Reticulopodia are ______-like series of cell extensions.
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Testate amebas with ______ pseudopodia, include Arcella and Diffligia.
Testate amebas with ______ pseudopodia, include Arcella and Diffligia.
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Growth and multiplication is by ______ fission involving nuclear division by mitosis followed by cytoplasmic division.
Growth and multiplication is by ______ fission involving nuclear division by mitosis followed by cytoplasmic division.
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Axopodia are thin ______ cell extensions supported by a central axis of microtubules.
Axopodia are thin ______ cell extensions supported by a central axis of microtubules.
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Under unfavourable conditions, Amoeba forms a ______ and remain inactive until moisture or warm temperature are restored.
Under unfavourable conditions, Amoeba forms a ______ and remain inactive until moisture or warm temperature are restored.
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Microsporidians once considered ______ protists are now classified as fungi.
Microsporidians once considered ______ protists are now classified as fungi.
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There may be ______ in other species like Entamoeba histolytica which undergo spore formation.
There may be ______ in other species like Entamoeba histolytica which undergo spore formation.
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The Diplomonads, Parabasalids, and Euglenozoans are genetically related and grouped under a ______ EXCAVATA.
The Diplomonads, Parabasalids, and Euglenozoans are genetically related and grouped under a ______ EXCAVATA.
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Giardia intestinalis lacks the characteristic ______ groove of the Excavata and inhabits the intestines of mammals.
Giardia intestinalis lacks the characteristic ______ groove of the Excavata and inhabits the intestines of mammals.
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Entamoeba coli is a ______ species that feed on bacteria and intestinal debris.
Entamoeba coli is a ______ species that feed on bacteria and intestinal debris.
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E.histolytica causes ______ dysentery and is spread via contaminated drinking water, food, or eating utensils.
E.histolytica causes ______ dysentery and is spread via contaminated drinking water, food, or eating utensils.
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Members of Opalinata are commensals in the ______ of frogs and toads.
Members of Opalinata are commensals in the ______ of frogs and toads.
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Diatom cells have a unique wall made of ______ dioxide embedded in an organic matrix.
Diatom cells have a unique wall made of ______ dioxide embedded in an organic matrix.
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The clade includes forms that are ______, others are ingesting heterotrophs, and still others are saprophytic.
The clade includes forms that are ______, others are ingesting heterotrophs, and still others are saprophytic.
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Opalinids are thought to have lost their ______ and replaced with rows of cilia.
Opalinids are thought to have lost their ______ and replaced with rows of cilia.
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Mitochondria have short ______ cristae.
Mitochondria have short ______ cristae.
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Almost all opalinids are endosymbiotic in the ______ of anurans where they ingest dissolved material.
Almost all opalinids are endosymbiotic in the ______ of anurans where they ingest dissolved material.
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They are among the most abundant ______ organisms both in the ocean and in lakes
They are among the most abundant ______ organisms both in the ocean and in lakes
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Diatom act as a ______ sink thereby playing a great role in ameliorating global warming
Diatom act as a ______ sink thereby playing a great role in ameliorating global warming
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Because their shells (frustules) are composed of ______, they are also extremely important for the biogeochemical cycling of silicon
Because their shells (frustules) are composed of ______, they are also extremely important for the biogeochemical cycling of silicon
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Diatom have caused deaths of ______, seabirds, fish and shellfish
Diatom have caused deaths of ______, seabirds, fish and shellfish
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Diatoms in the genus Pseudonitzschia are capable of producing the ______ acid that can accumulate in the food chain
Diatoms in the genus Pseudonitzschia are capable of producing the ______ acid that can accumulate in the food chain
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Brown algae is also known as ______ (kelp)
Brown algae is also known as ______ (kelp)
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Algin, extracted from ______ is used as an emulsifier in many things from paint to baby food to cosmetics
Algin, extracted from ______ is used as an emulsifier in many things from paint to baby food to cosmetics
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Oomycetes include the ______ molds, the white rusts, downy mildews, the potato blight
Oomycetes include the ______ molds, the white rusts, downy mildews, the potato blight
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Study Notes
Flagellum and Cytoskeleton
- A cross-section of a flagellum shows an outward extension of the cytoskeleton and cytoplasm, forming pseudopodia used for movement and feeding in amoebas.
- Different types of pseudopodia include lobopodia (blunt and broad, containing ectoplasm and endoplasm), filopodia (thread-like, containing ectoplasm only), and reticulopodia (net-like series of cell extensions).
Axopodia
- Axopodia are thin, filamentous cell extensions supported by a central axis of microtubules.
Classification of Protists
- Recent classification using metagenomic studies grouped protists according to their phylogenetic relatedness.
- Microsporidians, previously considered amitochondriate protists, are now classified as fungi.
Supergroup EXCAVATA
- The supergroup EXCAVATA includes Diplomonads, Parabasalids, and Euglenozoans, which are genetically related and grouped based on cytostkeletal and DNA sequence data.
- Members of EXCAVATA have a posteriorly directed flagellum, which generates a feeding current.
- Two major clades, Parabasalids and Diplomonads, have two nuclei, multiple flagella, and modified mitochondria.
- Euglenozoans have flagella that differ in structure from those of other organisms and have acquired chloroplasts through endosymbiosis.
- Excavates include parasites, as well as many predatory and photosynthetic species.
Diplomonads
- Diplomonads, such as Giardia intestinalis, have modified mitochondria called mitosomes, which lack functional electron transport chains and obtain energy through anaerobic pathways.
- They possess multiple posterior flagella and two haploid nuclei per cell.
Red Tide
- Red tide is a phenomenon caused by dinoflagellate toxins, which can be harmful to humans and animals.
- Closure of beaches during red tide events lasts until filter-feeders have digested all the dinoflagellate toxin.
Ciliophora
- Ciliophora features include:
- Cilia, often covering the entire cell or clustered in a few rows or tufts, used for swimming and feeding.
- Identical to flagella, but differ in number.
- May be fused into a sheet called an undulating membrane or smaller membranelles, used to propel food into the cytopharynx.
- May be fused forming stiffened tufts called cirri, used in locomotion by creeping ciliates.
- Possess two types of nuclei: micronuclei and macronuclei.
- Have a large contractile vacuole, complex organelles, and a pellicle that maintains the cell's shape.
- Food is ingested through the cytostome and cytopharynx, and digestion occurs within the food vacuole.
Paramecium
- Paramecium is a Ciliophoran that has a micronucleus for exchange of genetic information during conjugation and a macronucleus for producing RNA and proteins for daily functions.
- During asexual reproduction by binary fission, the macronucleus divides into two pieces, and new gullets and contractile vacuoles appear.
Conjugation in Ciliophora
- Conjugation is the temporary union of two individuals to exchange chromosomal material.
- During conjugation, the haploid micronuclei resulting from meiotic division function as gametes.
- The macronucleus disintegrates, and the micronucleus of each individual undergoes meiosis, giving rise to four haploid micronuclei, three of which degenerate.
Opalinata
- Opalinids are commensals in the rectum of frogs and toads, and are thought to have lost their flagellation and replaced with rows of cilia.
- They are endosymbiotic in the hindgut of anurans, where they ingest dissolved material.
- Sexual reproduction is by syngamy, and asexual reproduction is by binary fission.
Diatom
- Diatoms are unicellular algae that have a unique glass-like wall made of silicon dioxide embedded in an organic matrix.
- They are key components of marine ecosystems and contribute greatly to oceanic primary productivity.
- Diatoms act as a carbon sink, playing a great role in ameliorating global warming.
- Some marine diatoms produce toxins similar in potency to those seen in some dinoflagellates.
Brown Algae
- Brown algae, also known as seaweed (kelp), are multicellular protists that form an integral base to many coastal food webs.
- Algin, extracted from seaweed, is used as an emulsifier in many products.
Oomycetes
- Oomycetes include water molds, white rusts, downy mildews, and the potato blight.
- Most are heterotrophs that actively seek and engulf bacteria and other protists by phagocytosis.
- Some members referred to as naked amoebas lack a test (shell) or other supporting structures.
Amoeba
- Amoebas are heterotrophs that engulf bacteria and other protists by phagocytosis.
- Some members possess a test (shell) that may be calcareous, proteineous, siliceous, or chitinous.
- Large openings in the shell permit extension of the body and pseudopodia.
- Growth and multiplication are by binary fission, involving nuclear division by mitosis followed by cytoplasmic division.
Entamoebida
- Entamoebida are symbiotic parasites that infect all classes of vertebrate animals and some invertebrates.
- Humans are hosts to at least six species of Entamoeba, including E. coli, which is a commensal species that feeds on bacteria and intestinal debris, and E. histolytica, which is pathogenic and causes amoebic dysentery.
- Entamoebas leave as cysts in feces, and reinfection is via the mouth.
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Description
This quiz covers the different types of cellular extensions, including pseudopodia, lobopodia, filopodia, reticulopodia, and axopodia, and their functions in cell movement and feeding.
