Protists and Their Distinctions Quiz

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Questions and Answers

What distinguishes protists from prokaryotic cells?

Protists are less complex than prokaryotic cells.

Protists do not carry out photosynthesis.

Protists have organelles and are eukaryotic. (correct)

Protists are exclusively multicellular.

Which of the following types of protists combines photosynthesis and heterotrophic nutrition?

Unicellular protists

Heterotrophs

Mixotrophs (correct)

Photoautotrophs

Which statement about protist reproduction is accurate?

All protists reproduce sexually.

Protists do not employ any form of meiosis.

Protists exhibit both asexual and sexual reproduction. (correct)

Most protists reproduce exclusively asexually.

What characteristic is true of the structural diversity among protists?

Protists exhibit more structural and functional diversity than any other group of eukaryotes. Signup and view all the answers

Which nutritional mode represents the majority of protists?

A combination of autotrophic and heterotrophic nutrition Signup and view all the answers

What advantage did the host gain from maintaining the cyanobacterial endosymbiont?

A source of sugar from photosynthesis Signup and view all the answers

Which of the following groups is included in the clade Excavata?

Euglenozoans Signup and view all the answers

How do diplomonads primarily derive their energy?

From anaerobic biochemical pathways Signup and view all the answers

What is a key feature that distinguishes euglenozoans?

A spiral or crystalline rod in their flagella Signup and view all the answers

What type of nucleus do diplomonads have?

Two equal-sized nuclei Signup and view all the answers

What do parabasalids use to generate energy?

Hydrogenosomes Signup and view all the answers

Which group of organisms are known to have modified mitochondria and primarily inhabit anaerobic environments?

Diplomonads Signup and view all the answers

Which of the following is true about the evolutionary relationship of haptophytes and cryptomonads?

Their evolutionary relationship to other eukaryotes is uncertain. Signup and view all the answers

What happens to the three micronuclei that are produced during meiosis of micronuclei?

They disintegrate. Signup and view all the answers

How many rounds of mitosis are required to produce eight micronuclei from a single diploid micronucleus?

Three rounds of mitosis. Signup and view all the answers

What is the significance of foram tests in marine sediments?

They form an extensive fossil record. Signup and view all the answers

Which characteristic distinguishes rhizarian amoebas from those in other clades?

They have threadlike pseudopodia. Signup and view all the answers

After micronuclear fusion, what is the outcome of the two haploid micronuclei?

They fuse into a diploid micronucleus. Signup and view all the answers

What unique feature defines kinetoplastids among euglenozoans?

They possess an organized mass of DNA called a kinetoplast. Signup and view all the answers

How do trypanosomes avoid detection by the host's immune system?

By changing their surface proteins frequently. Signup and view all the answers

Which characteristic is NOT true of euglenids?

They possess a rigid cell wall. Signup and view all the answers

What are the three major clades that make up the SAR supergroup?

Stramenopiles, Alveolates, and Rhizarians. Signup and view all the answers

What is a distinctive feature of diatoms?

They possess a two-part, glass-like wall. Signup and view all the answers

Which of the following is a main role of stramenopiles in their ecosystems?

They are significant photosynthetic organisms. Signup and view all the answers

What happens to diatoms after their population blooms?

Many fall to the ocean floor undecomposed. Signup and view all the answers

What functional role does the eyespot in euglenids serve?

To detect light from specific directions for navigation. Signup and view all the answers

What structure is characteristic of members of the Alveolata clade?

Alveoli Signup and view all the answers

What is a primary feature of dinoflagellates?

They can be both phototrophs and heterotrophs. Signup and view all the answers

How do apicomplexans primarily reproduce?

Through sexual and asexual stages requiring multiple hosts. Signup and view all the answers

What is the role of cilia in ciliates?

For locomotion and feeding. Signup and view all the answers

What distinguishes the micronuclei of ciliates?

Micronuclei are involved in genetic variation through conjugation. Signup and view all the answers

What event leads to toxic 'red tides'?

Excessive nutrient runoff causing dinoflagellate blooms. Signup and view all the answers

What is the sporozoite stage in apicomplexans?

An infectious cell that spreads the parasite. Signup and view all the answers

What occurs during the conjugation process in ciliates?

Two cells exchange haploid micronuclei. Signup and view all the answers

What is the primary component of the internal skeleton of marine radiolarians?

Silica Signup and view all the answers

What type of feeding mechanism do radiolarians primarily use?

Phagocytosis Signup and view all the answers

Which characteristic is true of red algae?

They contain the pigment phycoerythrin. Signup and view all the answers

Which group of green algae is most closely related to land plants?

Charophytes Signup and view all the answers

What is a defining feature of cercozoans?

They have threadlike pseudopodia. Signup and view all the answers

Which statement is true about the relationships among archaeplastida?

Red algae, green algae, and land plants form a single eukaryotic subgroup. Signup and view all the answers

Where are chlorophytes primarily found?

In freshwater environments Signup and view all the answers

Which structure helps establish a new cell wall after cell division in charophytes?

Phragmoplast Signup and view all the answers

Study Notes

Protists: Overview

Protists are eukaryotes, meaning their cells have membrane-bound organelles.
They are more complex than prokaryotic cells.
Protists exhibit greater structural and functional diversity than any other group of eukaryotes.
Most protists are unicellular, but some are colonial or multicellular.
They can be photoautotrophs (photosynthetic), heterotrophs (absorbing or ingesting organic molecules), or mixotrophs (combining both).
They play key roles in their habitats, such as symbionts and producers.
Some protists reproduce asexually, while others reproduce sexually or employ sexual processes like meiosis and fertilization.
Protist diversity originates from endosymbiosis, where one cell engulfs another cell, which becomes an endosymbiont and then an organelle.

Protists: Excavata

The Excavata clade is characterized by its cytoskeleton.
Some members have an "excavated" feeding groove.
They are mostly heterotrophic.
This supergroup includes diplomonads, parabasalids, and euglenozoans.

Protists: Diplomonads

Lack plastids and have modified mitochondria (mitosomes).
Derive energy from anaerobic biochemical pathways.
Have two equal-sized nuclei and multiple flagella.
Often parasites, such as Giardia intestinalis.

Protists: Parabasalids

Lack plastids and have modified mitochondria (hydrogenosomes).
Generate energy anaerobically (releasing H₂).
They include Trichomonas vaginalis, a pathogen that causes yeast infections in human females.

Protists: Euglenozoans

A diverse group with predatory heterotrophs, photosynthetic autotrophs, and parasites.
Distinguished by spiral or crystalline rod inside their flagella.
Kinetoplastids and euglenids are included in this clade.
Kinetoplastids have a single mitochondrion with a kinetoplast (an organized mass of DNA).
Some are free-living consumers of prokaryotes in freshwater, marine, or moist ecosystems; others are parasitic (e.g., Trypanosoma, causing sleeping sickness).
Euglenids have one or two flagella emerging from a pocket.
Some can be both autotrophic (containing chloroplasts) and heterotrophic (mixotrophs).
They have an eyespot, a light detector;
The pellicle, protein bands beneath the plasma membrane, gives them strength and flexibility.

Protists: SAR

A diverse monophyletic supergroup defined by DNA similarities.
Includes stramenopiles, alveolates, and rhizarians.

Protists: Stramenopiles

Includes important photosynthetic organisms: diatoms, golden algae, and brown algae.
Most have a "hairy" flagellum paired with a "smooth" flagellum.
Diatoms are unicellular photosynthetic algae with unique two-part glass-like walls (frustules) made of silica. They are major components of phytoplankton; diatom blooms lead to the sinking of large amounts of dead diatoms, which removes CO₂ from the atmosphere.
Brown algae are multicellular and most are marine. They have the most complex multicellular anatomy of all algae.
Oomycetes include water molds, white rusts, and downy mildews; cell walls are made of cellulose, unlike fungi which have chitin in their cell walls.

Protists: Alveolates

Members have membrane-enclosed sacs (alveoli) just beneath the plasma membrane.
Include dinoflagellates, apicomplexans, and ciliates.
Dinoflagellates have two flagella embedded in grooves; they are abundant components of marine and freshwater phytoplankton and can form harmful blooms.
Apicomplexans are parasites; some cause serious human diseases; these protists use a complex of organelles (at the apex) to penetrate and infect host cells.
Ciliates use cilia for movement and feeding and have large macronuclei and small micronuclei; conjugation is a sexual process where micronuclei are exchanged, and this is different from binary fission which is an asexual process.

Protists: Rhizarians

Amoebas move and feed by pseudopodia; rhizarian amoebas have threadlike pseudopodia.
Include radiolarians, forams, and cercozoans
Foraminiferans or forams have porous multichambered shells (tests) with pseudopodia extending through the pores; their tests (shells) form a fossil record used to understand past changes in ocean temperature.
Radiolarians have delicate skeletons made of silica. Their pseudopodia radiate from the central body.
Cercozoans are mostly heterotrophic amoeboid and flagellated protists with threadlike pseudopodia; they are common in various ecosystems.

Protists: Archaeplastida

Includes red algae and green algae, which are closely related to land plants.

Protists: Unikonta

Includes protists closely related to fungi and animals.
Contains amoebozoans, and opisthokonts, comprising animals, fungi, and other related organisms.
Slime molds are amoeboid and include plasmodial and cellular slime molds;
Tubulinids include heterotrophic protists with lobe- or tube-shaped pseudopodia.
Entamoebas are parasites of vertebrates and invertebrates; Entamoeba histolytica causes amebic dysentery.
Opisthokonts include several groups of protists, and are closely related to fungi and animals.

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Description

Test your knowledge on the characteristics that distinguish protists from prokaryotic cells. This quiz covers topics including nutritional modes, reproduction, and structural diversity among protists. Explore the fascinating relationships and unique features that define these diverse organisms.