University:
Austin College
Course:
BIOLOGY 101 | General Biology
Academic year:

2024
Views:

302

Pages:

2
Author:

Marcella G.

CLASS PHAEOPHYCEAE (Blonde algae) Phaeophyceae are blonde algae. The chromatophore contains chlorophyll-a, carotene and santhophyll, but especially phycoxanthin which masks other colors and which causes the algae to appear blonde. Up to 50% of its dry weight consists of laminarin, a type of carbohydrate that resembles dextrin and is closer to cellulose than with flour. Apart from laminarin , manite, oil and other substances were also found . The cell wall consists of pectin, cellulose, algin. In Phaeophyceae the level of development that can move is in the form of zoospores and gametes, has 2 heteroconous whip reeds and is found on the side of the body in the form of a spring or spool. Most Phaeophyceae live in sea water, only a few types live deep freshwater. These algae include benthic, attached to rocks, wood, epiphytes on thallus and other algae, some even live as endophytes. 5.1. Phaeosporales This nation is mostly blonde algae. Most have a physique like Cladophora, but there are also those that have higher talus levels. Breeding occurs by: a. Asexual with zoospores, which occurs due to re-reduction. From the zoospores it grows Haploid gametophyte with checkered gamatangium. b. Sexual with isogamy. Multicellular gametangium. 5.2. Laminariles Nation This nation includes the Laminariaceae tribe, which includes, among others - Macrocystis pyrifera, lives in the south polar region, its thallus reaches a length of 60 m and weighs up to 100 kg. Having sheet-shaped talus branches hanging down, the talus can float on the surface of sea water. - Lessonia sp. Has a talus that looks like a palm tree. - Laminaria clustoni, the base of the thallus is as thick as an arm and is annual, the top resembles a leaf or has finger sheets which are renewed every year. In Laminaria there is a regular rotation of offspring. The gametophyte originates from zoospores, at the end of which there is an antheridim which consists of only one cell, each of which produces two spermatozoids which have two whip hairs. 5.3. Dictyotales Nation In this algae the spores do not have whip hairs. The sporangium bears one and releases 4 tetraspores. Sexual reproduction by oogamy. Male gametes have one whip feather on their side. The sporophyte and gametophyte are alternate and regular, and both have ribbon-shaped thallus which branch out into forks, for example Dictyota dichotoma. The Dictyotales nation consists of only one tribe, namely Dictyotaceae, which includes several types,among others : - Dictyotaceae dichotoma - Dictyopteris polypoides - Padina Pavonia