Protists: Choanoflagellates and Algae
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Questions and Answers

What is the primary component of the test of diatoms?

  • Silica (correct)
  • Calcium carbonate
  • Cellulose
  • Chitin

Which of the following statements is true regarding the Euglena genus?

  • They exclusively feed by absorption.
  • They can photosynthesize and capture their own food. (correct)
  • They are characterized by a rigid cell wall.
  • They possess only one type of flagellum.

What aids in light detection in Euglena organisms?

  • Red stigma (eyespot) (correct)
  • Chloroplasts
  • Mitochondria
  • Paramylon body

How many genera of euglenozoans have been described?

<p>1,000 genera (D)</p> Signup and view all the answers

What is the function of the pellicle in Euglena?

<p>Maintains cell shape and flexibility (A)</p> Signup and view all the answers

Which group do choanoflagellates belong to?

<p>Supergroup Opisthokonta (B)</p> Signup and view all the answers

What unique feature do choanoflagellates possess?

<p>A collar of tentacles (C)</p> Signup and view all the answers

Which of the following phyla includes diatoms?

<p>Phylum Bacillariophyta (C)</p> Signup and view all the answers

What is a characteristic of green algae (Phylum Chlorophyta)?

<p>They contain chlorophyll a and can be found on diverse substrates. (A)</p> Signup and view all the answers

Which of the following statements about algae is incorrect?

<p>All algae possess chlorophyll a. (D)</p> Signup and view all the answers

Which type of algae is most numerous in marine and freshwater environments?

<p>Diatoms (A)</p> Signup and view all the answers

What do green algae and modern plants have in common?

<p>Both possess chlorophyll a. (C)</p> Signup and view all the answers

Where can some species of green algae be found growing?

<p>On the surfaces of tree trunks and buildings (D)</p> Signup and view all the answers

Flashcards

Diatoms

Microscopic algae with intricate, geometric shapes. Their cell walls are made of silica, similar to glass.

Diatomaceous Earth

A natural deposit of fossilized diatoms. It's used in various products like silverware polish, insulation, and toothpaste.

Euglenophyta

A group of algae with about 1000 species, mostly freshwater. They are known for having flagella for movement.

Pellicle

A flexible, protein-based layer that surrounds Euglenophyta. It provides support but allows for shape changes.

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Euglena

A common type of Euglenophyta found in freshwater. It has both a chloroplast for photosynthesis and a gullet for food ingestion.

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Choanoflagellates

Single-celled or colonial protists considered potential ancestors of fungi and animals. They have a single flagellum and a collar of tentacles.

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Opisthokonta

A supergroup of eukaryotic organisms that includes fungi and animals, and is believed to be a descendant of choanoflagellates.

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Algae

Diverse group of plant-like protists, from microscopic diatoms to giant kelp. They photosynthesize.

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Chlorophyll a

A pigment essential for photosynthesis found in algae, plants, and some bacteria. Absorbs light energy.

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Green Algae (Chlorophyta)

Phylum of about 10,000 species, mostly aquatic, including single-celled and multicellular forms. They are thought to be ancestors of plants.

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Diatoms (Bacillariophyta)

Phylum of single-celled algae with unique, intricate glass shells. They are crucial to marine and freshwater ecosystems.

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Test

The hard, protective outer shell of a diatom, made of two halves.

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Archaeplastida

A major group of eukaryotes that includes red algae, green algae, and plants. Characterized by the presence of chloroplasts.

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Study Notes

Choanoflagellates

  • Choanoflagellates are protists, possibly ancestral to fungi and animals.
  • They exist as single cells or in colonies in freshwater and marine environments.
  • Their structure resembles collar cells in sponges - a single flagellum surrounded by a collar of cytoplasmic extensions (tentacles).
  • They are part of the Opisthokonta supergroup, which includes fungi and animals.

Algae

  • Algae are diverse photoautotrophic protists, ranging from microscopic diatoms to large kelp.
  • They contain chlorophyll a and plastids, producing oxygen and forming the base of food chains.
  • Traditionally, algal phyla are categorized by accessory pigments; examples of phyla studied are Chlorophyta, Rhodophyta, Bacillariophyta (diatoms), and Euglenophyta.

Green Algae (Chlorophyta)

  • Chlorophyta (green algae) are in the Archaeplastida group, comprising about 10,000 unicellular and multicellular species.
  • Mostly aquatic, some live on various surfaces (tree trunks, etc) and even on sloths.
  • Considered ancestors of modern plants.

Diatoms (Bacillariophyta)

  • Diatoms are uniquely shaped, single-celled algae in the Stramenopiles group.
  • Possess a silica shell (test) composed of two halves.
  • Abundant in marine and freshwater environments, with estimated species ranging from 10,000 to a million.
  • Silica-based shells make them common in the fossil record; diatomaceous earth is a significant deposit used in various products.

Euglenophyta

  • Euglenophyta (euglenoids) are single-celled, flagellated freshwater organisms in the Excavata group.
  • Approximately 1,000 species, roughly half are photosynthetic, and half are non-photosynthetic.
  • Non-photosynthetic species feed by particle ingestion and absorption.
  • Photosynthetic euglenoids (e.g., Euglena) are characterized by chloroplasts, a pellicle (helical protein bands), and visible flagella for movement, a paramylon body, a gullet, and a red eyespot.

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Description

Explore the fascinating world of protists in this quiz, focusing on choanoflagellates and the diverse algae. Learn about their structures, classifications, and ecological importance. This quiz will evaluate your understanding of these crucial organisms and their roles in aquatic environments.

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