Biology Chapter on Protists

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Questions and Answers

What distinguishes protists from prokaryotic organisms?

Protists have membrane-enclosed organelles. (correct)

Protists lack a nucleus.

Protists are exclusively found in marine environments.

Protists are multicellular only.

Which of the following describes the nutritional strategy of mixotrophic protists?

They exclusively absorb organic molecules.

They are capable of producing their own food via chemosynthesis.

They primarily rely on photosynthesis.

They combine photosynthesis and heterotrophic nutrition. (correct)

What is the significance of endosymbiosis in the evolution of protists?

It indicates a relationship where one organism lives within another. (correct)

It suggests that protists are exclusively unicellular organisms.

It explains why all protists are autotrophic.

It provides evidence that protists can only exist as parasites.

Which of the following roles do protists play in aquatic ecosystems?

They can function as producers and are essential for food webs. Signup and view all the answers

What characteristic is common among the four supergroups of protists?

All have a shared evolutionary lineage. Signup and view all the answers

Which hypothesis suggests that viruses evolved from molecules of proteins and nucleic acids before the existence of cells?

Virus-first hypothesis Signup and view all the answers

What are the smallest infectious agents that require an electron microscope for detection?

Viruses Signup and view all the answers

What is the term for a virus that contains an additional covering beyond the nucleocapsid?

Enveloped virus Signup and view all the answers

Which characteristic is unique to the diplomonads among the Excavata?

Possession of mitosomes Signup and view all the answers

The capsid of a virus is composed of several identical protein subunits known as what?

Capsomers Signup and view all the answers

What primarily distinguishes parabasalids from diplomonads?

Type of energy source utilized Signup and view all the answers

What do all members of the SAR supergroup have in common?

Possess secondary endosymbiotic chloroplasts Signup and view all the answers

Which hypothesis explains that some viruses may have evolved from genetic material that escaped from larger organisms?

Escape hypothesis Signup and view all the answers

What do all viruses contain that allows them to invade and control host cells?

Capsids and nucleic acids Signup and view all the answers

Which of the following features does not apply to euglenozoans?

They are exclusively autotrophic. Signup and view all the answers

What is the primary significance of reduced mitochondria in diplomonads?

Facilitation of anaerobic respiration Signup and view all the answers

What is the size of the smallest known viruses, like parvovirus?

20 nm in diameter Signup and view all the answers

What term describes viruses that only have a nucleocapsid and lack an additional envelope?

Naked viruses Signup and view all the answers

Which of the following is an example of a parabasalid?

Trichomonas vaginalis Signup and view all the answers

What adaptation do euglenozoans have that aids in their mobility?

Spiral or crystalline structures in flagella Signup and view all the answers

Which characteristic best describes the Feeding strategy of Excavata?

Adaptation to anaerobic environments Signup and view all the answers

What are biological agents primarily known for?

Causing harm or disabling people, animals, and plants Signup and view all the answers

Which of the following is NOT a method by which biological agents can be spread?

Physical shielding with barriers Signup and view all the answers

Which type of biological agent is NOT listed as a likely weapon in biological warfare?

Parasites Signup and view all the answers

What historical event involved the use of cadavers to spread plague to an enemy city?

Siege of Caffa Signup and view all the answers

What tactic was commonly used in European wars to weaken the opposing army?

Poisoning the water supply Signup and view all the answers

During which war did bodies of dead soldiers get catapulted into enemy ranks?

Battle of Karolstein Signup and view all the answers

Which year was the Black Death pandemically recognized?

14th century Signup and view all the answers

What was one of the proposed origins of the plague pandemic during the Black Death?

Far East regions Signup and view all the answers

What is a characteristic feature used for the naming of virus families?

Presence of capsid Signup and view all the answers

Which of the following correctly describes the classification of viruses?

Viruses are categorized as DNA or RNA viruses. Signup and view all the answers

Which type of enzymes might be found in a virus particle that aids in replication?

Polymerases Signup and view all the answers

What are the general phases in the life cycle of animal viruses?

Absorption, penetration, synthesis, assembly, release Signup and view all the answers

Which suffix is commonly used for virus families in their nomenclature?

-viridae Signup and view all the answers

What distinguishes enveloped viruses from naked viruses?

Presence of a lipid membrane Signup and view all the answers

What is the role of replication enzymes found in some viruses?

To replicate viral nucleic acids Signup and view all the answers

Which of the following is not a common criterion for classifying viruses?

Host organism Signup and view all the answers

What distinguishes red algae from other types of algae?

Presence of phycoerythrin pigment Signup and view all the answers

Which of the following characteristics best describes slime molds?

They form a structure called plasmodium during growth. Signup and view all the answers

Which group is most closely related to fungi and animals?

Unikonta Signup and view all the answers

What is a key feature of charophytes among green algae?

They possess structures similar to chloroplasts of plants. Signup and view all the answers

How do red algae achieve fertilization?

By relying on water currents to transport gametes. Signup and view all the answers

Which statement about amoebozoans is true?

They include slime molds and many species of amoebas. Signup and view all the answers

What defines the difference between plasmodial slime molds and other molds?

They form a mass called plasmodium during reproduction. Signup and view all the answers

Which of the following best describes chlorophytes?

They exhibit a wide range of forms, including unicellular and multicellular organisms. Signup and view all the answers

Study Notes

Protists - Overview

Eukaryotic organisms
Possess a nucleus and a nuclear envelope
Contain membrane-enclosed organelles
Extremely diverse
Mostly unicellular, but some are multicellular

Protist Nutrition

Some are photoautotrophs (contain chloroplasts)
Others are chemoheterotrophs (absorb or ingest organic molecules)
Mixotrophs use both photosynthesis and heterotrophic nutrition

Endosymbiosis

Symbiotic relationship where one organism lives within another
Some scientists theorize protists and eukaryotes evolved through host cells engulfing bacteria
Many protists exist by living within other organisms
This symbiotic relationship can be parasitic

Symbiotic Relationships With Protists

Many are aquatic, found wherever water is present
Some are mutualistic (e.g., in coral reefs)
Others depend on protists for food (e.g., producers that convert light to nutrients)
Some are parasitic (e.g., those in intestines, malaria)

Supergroups of Protists

Excavata
SAR
Archaeplastida
Unikonta Each supergroup has unique features and varying clinical/environmental significance.

Excavata

Possess an "excavated" feeding groove
Modified mitochondria (mitosomes) for anaerobic respiration
Unique flagella for mobility and predation
Includes diplomonads, parabasalids, and euglenozoans.

Diplomonads

Reduced mitochondria (mitosomes) lack electron transport chains
Obtain energy through anaerobic pathways
Two equal nuclei and multiple flagella facilitate rapid reproduction and movement
Primarily parasitic, such as Giardia intestinalis (intestinal infection)

Parabasalids

Reduced mitochondria (hydrogenosomes)
Parasitic
Examples include Trichomonas vaginalis (sexually transmitted disease)

Euglenozoans

Diverse (predatory, photosynthetic, mixotrophic, parasitic)
Rod-shaped structure within flagella
Includes Trypanosoma (sleeping sickness, transmitted by tsetse flies)

SAR

Stramenopiles
Alveolates
Rhizarians

Stramenopiles

Flagellum with hair-like projections
Includes diatoms, golden algae, and brown algae

Diatoms

Unicellular algae with silicon dioxide walls
Photosynthetic, impacting CO2 levels
Important in marine and freshwater environments

Golden Algae

Unicellular
Yellow-brown pigmentation (carotenoids)
Biflagellated cells (two flagella)
Mostly freshwater

Brown Algae

Multicellular
Brown pigmentation (carotenoids)
Marine
Often called "seaweeds"

Alveolates

Membrane-enclosed sacs (alveoli) beneath plasma membrane
Dinoflagellates, apicomplexans, and ciliates

Dinoflagellates

Two flagella in grooves
Some are photosynthetic, others are mixotrophic
Some produce toxins causing red tides

Apicomplexans

Parasites of animals
Sporozoite cells, specialized for host cell penetration
Often require multiple host species in their life cycle
Malarial parasite, Plasmodium, is an example

Rhizarians

Varying features
Pseudopodia (extensions for movement and feeding)
Includes radiolarians and forams

Archaeplastida

Red algae
Green algae

Red Algae

Multicellular
Rhodophytes
Photosynthetic pigment phycoerythrin masks chlorophyll
Abundant in warm, coastal tropical waters

Green Algae

Similar structure and pigments to chloroplasts of plants
Two types: charophytes (more similar to plants) and chlorophytes

Unikonta

Closely related to fungi and animals
Includes amoebozoans and opisthokonts

Amoebozoans

Amoebas with lobe-shaped or tube-like pseudopodia
Some are slime molds

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Description

Explore the fascinating world of protists in this quiz. Learn about their diverse forms, nutritional strategies, and ecological relationships including mutualism and parasitism. Delve into the endosymbiotic theories and the significance of protists in various ecosystems.