Question Video: Recalling the Characteristics of the Pyrrophyta Phylum | Nagwa Question Video: Recalling the Characteristics of the Pyrrophyta Phylum | Nagwa

Question Video: Recalling the Characteristics of the Pyrrophyta Phylum Biology • First Year of Secondary School

The kingdom Protista is divided into multiple phyla. Which of the following statements best describes organisms belonging to the Pyrrophyta phylum? [A] Organisms are unicellular, they inhabit fresh water or salt water, and most contain chloroplasts to carry out photosynthesis. [B] Organisms are mostly unicellular algae, with their cells often containing chloroplasts and the cell walls containing silica. [C] Organisms are unicellular, they often inhabit water or moist soils, and they can act as parasites. [D] Organisms move by the use of flagella, their cells contain photosynthetic pigments, and nearly all species are classed as phytoplankton.

03:18

Video Transcript

The kingdom Protista is divided into multiple phyla. Which of the following statements best describes organisms belonging to the Pyrrophyta phylum? (A) Organisms are unicellular, they inhabit fresh water or salt water, and most contain chloroplasts to carry out photosynthesis. (B) Organisms are mostly unicellular algae, with their cells often containing chloroplasts and the cell walls containing silica. (C) Organisms are unicellular, they often inhabit water or moist soils, and they can act as parasites. Or (D) organisms move by the use of flagella, their cells contain photosynthetic pigments, and nearly all species are classed as phytoplankton.

The kingdom Protista is divided into multiple phyla, including Protozoa, Euglenophyta, Chrysophyta, and Pyrrophyta, which this question concerns. Many of the organisms that belong to the Pyrrophyta phylum are commonly known as dinoflagellates. The suffix -flagellates refers to the fact that they are motile organisms that use their two flagella for locomotion. And the prefix dino- originates from the Greek word dinos, which means whirling, describing how these flagella move.

Organisms belonging to the phylum Pyrrophyta contain photosynthetic pigments such as chlorophyll that often give them a yellowish-green or golden-brown color. Some organisms belonging to this phylum are even bioluminescent, from which their name derived, as the prefix pyr- comes from the Greek word for fire, referring to the luminescent glow emitted by some of these organisms in darkness.

Their photosynthetic pigments liken them to plants, which are also usually photosynthetic and result in them often being referred to as phytoplankton. This word derives from the Greek words meaning plant wanderer, as they drift through their watery environment photosynthesizing much like a land plant would, even though they are usually classified in an entirely different kingdom to plants.

First, let’s talk about option (B): organisms are mostly unicellular algae, with their cells often containing chloroplasts and the cell walls containing silica. While these organisms are mostly unicellular algae and often contain chloroplasts, their cell walls do not usually contain silica and are instead made up primarily of cellulose like the cells of many plants. Therefore, we can eliminate this answer.

We can also eliminate option (C) — organisms are unicellular, they often inhabit water or moist soils, and they can act as parasites — because Pyrrophyta do not often inhabit moist soils. Instead, they mostly live in marine, salt water, or sometimes fresh water habitats.

Now, let’s take a look at option (A): organisms are unicellular, they inhabit fresh water or salt water, and most contain chloroplasts to carry out photosynthesis. These are all true to the Pyrrophyta phylum. However, it is not the best answer because it misses a key component of the organisms that belong to this phylum, which is the use of flagella for motility.

The best answer to describe organisms belonging to the Pyrrophyta phylum would therefore be option (D): organisms move by the use of flagella, their cells contain photosynthetic pigments, and nearly all species are classed as phytoplankton.

Join Nagwa Classes

Attend live sessions on Nagwa Classes to boost your learning with guidance and advice from an expert teacher!

  • Interactive Sessions
  • Chat & Messaging
  • Realistic Exam Questions

Nagwa uses cookies to ensure you get the best experience on our website. Learn more about our Privacy Policy