Chapter 20: Multicellular Algae
Characteristics of Algae
-Algae are photosynthetic organisms
-Live in streams, ponds, lakes, oceans, and swamps
-Must live in or near a source of water
-Algae lack an internal system
-Algae lack an internal system of tubes to move water and materials from one part to another
-Water in which algae live provides CO2, oxygen, nutrients, and carries away wastes
-Can be multicellular or unicellular
-Algae cells have cell walls
-Algae have chlorophyll a and other chlorphylls
-Reproductive cycle alternates between sexual and asexual
-Dispute over whether kingdom Protista or kingdom Plantae
Adaptations of Algae to Life Under Water
-Do not need to worry about drying out
-Many algae have very think, leaflike structure that's not waterproof
-Structures can exchange nutrients, oxygen, CO2 with the water
-Do not need stemlike structures
-Water keeps them supported
-Sexual reproduction is easier in water
-Sex cells can swim through water
Chlorophyll and Accessory Pigments
-Major problem for water plants is lack of light for photosynthesis
-Sea water absorbs red and violet which is what chlorophyll a uses best
-Light becomes dimmer and bluer in color as depth of the water increases
-Algae have evolved various forms of chlorophyll
-All have a
-B, C, D
-Accessory pigments are light absorbing compounds
-Absorb different wavelengths of light than chlorophyll absorbs
-Pass on the energy they absorb to the photosynthetic structures
-Reflect different wavelengths = give algae a wide range of colors
Groups of Algae
-Colors provided by chlorophyll and accessory pigments and form in which food is stored are used to classify algae
Chlorophyta - The Green Algae
-Green algae live primarily in moist areas on land and in fresh water
-Some live in oceans
-A colony is a group of cells that are joined together and show few specialized structures, or...
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