Protista: Algae Characteristics and Habitat

Kingdom Protista

• Algae belong to the kingdom Protista
• Algae are earlier autotrophic protists with unique metabolic processes
• They produced and released the first oxygen gas in the world

Habitat of Algae

• Algae can be located in forest and urban areas
• Algae can be found in water bodies, waterlogged and moist soils, trees, metals, and sculptures in moist conditions

Characteristics of Algae

• Fossil and chemical evidence show that algae are eukaryotes
• Algae appeared in the fossil record 1.5 billion years ago (BYA)

Forms of Algae

• Algae come in two main forms: microalgae and macroalgae
• Microalgae form a larger percentage of the world population of algae
• Forms of microalgae include unicellular forms such as Scenedesmus, Desmids, and Euglena
• Macroalgae are multicellular like higher plants but have false roots, stem, and leaves
• Multicellular forms of macroalgae include brown algae (Phaeophyta), green algae (Chlorophyta), and red algae (Rhodophyta)

Biology of Algae

• Algology (Phycology) is the study of algae, derived from the Latin word for "seaweed"
• Algae are autotrophic, primary producers, and a resource in aquatic and terrestrial food chains/webs
• They trap solar energy directly from the atmosphere

Impact of Algae on the Environment

Positive Impacts

• Algae are a source of food for many aquatic animals, from tiny shrimps to whales
• Algae produce 80% of the world's total food supply
• Algae produce more oxygen than all plants in the world (75%)
• Algae synthesize simple minerals into complex organic matter

Negative Impacts

• Algal bloom can be caused by high levels of phosphorous and nitrate in water
• Bacterial bloom can change the water color to cloudy white
• Algal bloom can cause mass mortality of higher organisms

Overview of Gymnosperms

• Gymnosperms are the 1st vascular plant with naked seeds.
• They are the 2nd vascular plant on land.
• They have advanced multicellular sex organs (embryophytes).
• Gymnosperms comprise ≤ 5% of the whole plant kingdom.
• They are regarded as the first tree to grow after the Noah’s flood!

Types of Gymnosperms

• They include: Conifer, Cycad, Ginkgo, and Gnetae.

Biology of Gymnosperms

• Gymnosperm belong to division spermatophyte.
• Gymnosperms consist of 2-members.
• They are softwoods of the plant kingdom.
• They are classified into Cycadophytes and Coniferophytes.

Facts about Gymnosperms

• They are first tree to grow after the Noah’s flood.
• They are softwoods of the plant kingdom.
• The two oldest living gymnosperms are Great Basin Bristlecone and Pine of Nevada (≈ 5,000-year-old).
• Cycads are the second largest living gymnosperms.

Reproduction in Gymnosperms

• Methods of reproduction in gymnosperm: Vegetative strategy and Sexual strategy.

Vegetative Strategy

• Vegetative strategies involve branch contact with substrate, taking root, and growing (very rare).

Sexual Strategy

• Sex organs are: Microsporangia and Megasporangia.

Fertilization of Gymnosperms

• Pollen transfer by wind to archegonium.
• Fuses with mature egg nucleus eight or more diploid nuclei.

Classification of Gymnosperms

• Spermatophyta is classified into Angiosperm and Gymnosperm.
• Gymnosperms are classified into Cycadophytes and Coniferophytes.
• Cycadophytes are classified into Cyadofilicales, Cycadeoidales, and Cycadales (only Cycadales is extant).
• Coniferophytes are classified into Corditales (extinct), Coniferales, Ginkgoales, and Gnetales (all extant).

Characteristics of Gymnosperms

• Gymnosperms are seed plants with naked ovules.
• They have evergreen pines (needle-like) leaves and soft wood.
• Other leaf forms are fan-like (Ginkgo), palm-like (cycad), and strap-like (Gnetae).
• Few genera are deciduous in habit (Ginkgo).

Habitats of Gymnosperms

• Gymnosperms are wildly distributed all over the world from extremely dry deserts to extremely moist rainforests in Northern temperate forests, equatorial regions, and High Mountains (China).

Ecology of Gymnosperms

• All cycads contain an endophyte (Cyanobacterium).
• Roots (coral-shaped) trap atmospheric nitrogen gas and fix into nitrate in nutrient poor habitats for plant use.

Economic uses of Gymnosperms

• Resins are powerful medicine that quicken to harden when in contact with air.