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Biology - Protista

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    Study Guide Biology – Protista 1. Algae Algae are a large and diverse group of organisms that can make their own food using photosynthesis. They may be unicellular (single - celled) or multicellular , and all of them are eukaryotes , meaning their cells have a nucleus. Even though algae look plant - like, they are not classified as plants . They are considered plant - like because they contain chloroplasts with chlorophyll , which allow them to carry out photosynthesis. Most algae live in the oceans , but many species are also found in freshwater environments such as lakes and ponds. Scientists divide algae into several major divisions (instead of phyla, which are used for protozoa). These divisions are mainly based on the types of pigments the algae contain and their overall color . The main divisions are: • Rhodophyta • Pyrrophyta • Chrysophyta • Phaeophyta • Chlorophyta 1. 1 Rhodophyta (Red Algae) Rhodophyta includes the red algae , which are found almost entirely in marine (saltwater) environments . • Most red algae are unicellular , but some are multicellular . • Larger forms grow attached to rocks below the low - tide level , and some are large enough to be called seaweeds . • They carry out photosynthesis using chlorophyll a .

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    Study Guide • Their red color comes from pigments that are similar to those found in cyanobacteria . A very important product made from red algae is agar . Agar is widely used in laboratories as a solid growth medium for bacteria . 1. 2 Pyrrophyta (Dinoflagellates) The division Pyrrophyta includes organisms called dinoflagellates . • Dinoflagellates are unicellular and often have thick protective plates, giving them an armored appearance . • They move using two flagella , which help them swim. • Many dinoflagellates are bioluminescent , meaning they give off light when disturbed, such as by waves or movement in the water. Under ideal ocean conditions, dinoflagellates can reproduce very rapidly. When this happens, their red pigments can cause the water to turn a reddish color , a phenomenon known as red tide . 1. 3 Chrysophyta (Golden Algae) Members of the division Chrysophyta are known as golden algae , and most of them are diatoms . • Diatoms have unique cell walls made of silica (a glass - like material). • Their cell wall is formed of two overlapping halves , similar to a box with a lid. • Diatoms are photosynthetic and play a crucial role in marine food chains , serving as a major food source for many organisms. Over time, the silica shells of diatoms can accumulate and form a porous rock called diatomaceous earth . This material is processed into diatomite , which is used: • as a filler , • as an absorbent , and • as a filtering agent .

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    Study Guide 1. 4 Phaeophyta (Brown Algae) The division Phaeophyta includes the brown algae , which are all multicellular . • These algae are found almost exclusively in saltwater . • Common examples include rock weeds and kelp , some of which can grow to very large sizes. Even though brown algae can be huge, their internal structure is much simpler than that of true plants . Many brown algae are harvested and used as: • fertilizers , and • sources of iodine . 1. 5 Chlorophyta (Green Algae) Chlorophyta includes the green algae , which are especially important in understanding evolution. • Some green algae are flagellated and can move. • A common laboratory example is Spirogyra . • Many species form colonies , where groups of cells live together and cooperate. These colonial green algae are thought to show some of the earliest steps toward multicellularity . They have features that are between single - celled organisms and complex multicellular organisms . Another well - known member of this group is Ulva , commonly called sea lettuce , which is found in marine environments. 2. Quiz Algae 1. Question Why are algae considered plantlike? Answer Choices • They have chloroplasts filled with chlorophyll.

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    Study Guide • They have roots. • They have vascular tissue composed of xylem and phloem. Correct Answer They have chloroplasts filled with chlorophyll. Why This Is Correct Algae are considered plantlike because they contain chloroplasts with chlorophyll, which allows them to perform photosynthesis. This is a key characteristic of plants. Algae do not have true roots, and they also lack vascular tissues like xylem and phloem, which are found in higher plants. 2. Question How are algae subdivided into divisions? Answer Choices • by food source • by locomotion • by types of pigments Correct Answer by types of pigments Why This Is Correct Algae are divided into different groups based on the types of pigments they contain. These pigments affect their color and how they capture light for photosynthesis. For example, some algae appear green, red, or brown because of differences in their photosynthetic pigments — not because of how they move or what they eat.

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    Study Guide 3. Question Which of the following include red algae that photosynthesize using chlorophyll a ? Answer Choices • Chrysophyta • Pyrrophyta • Rhodophyta Correct Answer Rhodophyta Why This Is Correct Rhodophyta is the division that includes red algae. These algae contain chlorophyll a , which allows them to carry out photosynthesis. Chrysophyta and Pyrrophyta are other algal divisions, but they do not include red algae. 4. Question Which of the following are the golden algae? Answer Choices • Chlorophyta • Chrysophyta • Phaeophyta Correct Answer Chrysophyta Why This Is Correct

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    Study Guide Chrysophyta are known as the golden algae because they contain pigments that give them a golden or yellow - brown color. Chlorophyta are green algae, and Phaeophyta are brown algae, so neither of those choices is correct. 5. Question Which of the following may be luminescent? Answer Choices • Chrysophyta • Phaeophyta • Pyrrophyta Correct Answer Pyrrophyta Why This Is Correct Pyrrophyta (also known as dinoflagellates) may be luminescent. Some species can produce light, causing glowing effects in ocean water at night. Chrysophyta (golden algae) and Phaeophyta (brown algae) do not typically show luminescence. 6. Question Which of the following is the main component of the bacteriological medium called agar? Answer Choices • Chlorophyta • Pyrrophyta • Rhodophyta

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    Study Guide Correct Answer Rhodophyta Why This Is Correct Agar is derived from red algae , which belong to the division Rhodophyta . Substances extracted from these algae are used to make agar, a solidifying agent commonly used in bacteriological culture media. Chlorophyta (green algae) and Pyrrophyta (dinoflagellates) are not sources of agar. 7. Question Which of the following are surrounded by thick plates that give them an armored appearance? Answer Choices • Chrysophyta • Phaeophyta • Pyrrophyta Correct Answer Pyrrophyta Why This Is Correct Pyrrophyta (dinoflagellates) are surrounded by thick cellulose plates that form an outer covering. These plates give them a distinctive armored appearance . Chrysophyta (golden algae) and Phaeophyta (brown algae) do not have this plated, armored structure. 8. Question Which of the following compose a red tide?

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    Study Guide Answer Choices • Chlorophyta • Chrysophyta • Pyrrophyta Correct Answer Pyrrophyta Why This Is Correct Pyrrophyta (dinoflagellates) are responsible for red tides. During rapid population growth, these organisms can discolor ocean water and may release toxins that affect marine life and humans. Chlorophyta (green algae) and Chrysophyta (golden algae) do not typically cause red tides. 9. Question Which of the following have cell walls composed of two overlapping halves impregnated with silica? Answer Choices • Chrysophyta • Phaeophyta • Pyrrophyta Correct Answer Chrysophyta Why This Is Correct Chrysophyta include diatoms, which have unique cell walls made of silica . These walls consist of two overlapping halves , fitting together like a petri dish. Phaeophyta (brown algae) and Pyrrophyta (dinoflagellates) do not have silica - impregnated, two - part cell walls.

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    Study Guide 10. Question Which of the following are known as rock weeds and kelps? Answer Choices • Chrysophyta • Phaeophyta • Pyrrophyta Correct Answer Phaeophyta Why This Is Correct Phaeophyta are the brown algae, which include rock weeds and kelps . These algae are usually large, multicellular, and found in marine environments, especially along rocky coastlines. Chrysophyta (golden algae) and Pyrrophyta (dinoflagellates) are not known as rock weeds or kelps. 11. Question Which of the following are often sources of iodine? Answer Choices • Chrysophyta • Phaeophyta • Pyrrophyta Correct Answer Phaeophyta Why This Is Correct

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