Biology 11. Day 4 Classification of Algae

Transcription

1 Biology 11 Day 4 Classification of Algae

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3 Learning Objectives: Become familiar with biological nomenclature Distinguish between Rhodophyta, Phaeophyta, and Chlorophyta Identify features of each body type within Chlorophyta Name and describe groups with each body type within Chlorophyta Explain the biological significance of Volvox and Ulva Textbook p , Study Guide p

4 Nomenclature Species are described with a two part naming system developed by Swedish botanist Carl Linnaeus. Recall that organisms are part of a Kingdom, Phylum, Class, Order, Family, Genus, and Species. All of these have latin names recognized universally within western science. Latin names are always written in italics. Species are described with Genus species. For example, the Douglas fir is called Pseudotsuga menziesii. Humans are Homo sapiens. We are part of the genus Homo, species sapiens.

5 Algae Classification There are three main groups of algae: Rhodophyta, Phaeophyta, and Chlorophyta Rhodophyta is known as red algae Phaeophyta is known as brown algae Chlorophyta is known as green algae Algae Rhodophyta Phaeophyta Chlorophyta

6 Rhodophyta The Red Algae Marine algae present all over the world Contains pigments chlorophyll-a, chlorophyll-d, and phycobilin. Can live quite deep under water due to accessory pigment phycobilin which is efficient at absorbing blue light. Nori, the seaweed used to wrap sushi rolls, is dried Porphyra, a type of red algae.

7 Phaeophyta The Brown Algae Most seaweed is brown algae Lives in temperate or arctic waters Includes the largest algae Giant Kelp

8 Chlorophyta The Green Algae Algae Rhodophyta Phaeophyta Chlorophyta 4 types types: unicellular, colonial, filamentous, leaf-like. Primarily in moist areas on land and in fresh water. Reproductive cycle includes sexual and non-sexual stages. Similar to land plants: Have cellulose in their cell walls, contain chlorophylls a and b, store food in the form of starch, and has a reproductive cycle remarkable similar to moss. Scientists believe that green algae and moss shared a common ancestor

9 Algae Rhodophyta Phaeophyta Chlorophyta Unicellular Colonial Filamentous Leaf-Like

10 Unicellular - Chlamydomonas Grows in ponds, ditches, and wet soil. Main features: 2 flagella for a movement and an eye spot to detect light, cup-shaped chloroplast for photosynthesis, pyrenoid to synthesis and store starch. No cellulose in cell wall

11 Colonial - Volvox Colonial organisms live in communities where many small individuals work together to behave as one larger individual. Volvox comes in communities of cells that work together. Cells are connected to each other by strands of cytoplasm, allowing them to communicate. A few cells are specialized for reproduction. Volvox straddles colonial and multicellular life.

12 Filamentous Spirogyra and Oedogonium Form long thread-like colonies. Can reproduce asexually. If the strand is broken, both pieces will continue to divide and grow. They can also reproduce sexually using specialized reproductive cells called gametes.

13 Leaf-life - Ulva Multicellular green algae also called sea lettuce. Commonly found along rocky sea coasts. Tough enough to withstand waves, held in place by a holdfast. Ulva is significant in biology because it s reproductive cycle is very similar to that of mosses and ferns.

14 Alternation of Generations Many non-vascular plants (Ulva, some other algae, mosses, and ferns) use a reproductive strategy called alternation of of generations. They will reproduce sexually, then asexually, then sexually, then asexually, etc. One generation will be haploid, the next will be diploid, the next will be haploid, etc.

15 Check your understanding How is red algae adapted to life deep under water? It contains phycobilin, a pigment efficient at absorbing the blue light that makes it deep below the surface. Which phylum does most of our seaweed here in Canada belong to? Phaeophyta Brown algae What is the purpose of a pyrenoid? Synthesizes and stores starch. What is the biological significance of Volvox? Bridges the gap between colonial and multicellular life. What is the biological significance of Ulva? Exhibits alternation of generations, similar to mosses and ferns.