Lecture XVII: Producers Flashcards
What makes a living organism a producer?
They have the ability to produce organic compounds (e.g. glucose) from CO2. The organic compounds they make will provide all heterotrophic organisms with energy and the building blocks to make their own structure.
Therefore, producers form the base of all food chains, both aquatic and terrestrial.
All producers are Autotrophic
Chemoautotrophs:
E source = Inorganic chemicals
e.g. Oxidation of H2S produces energy for certain archaea and bacteria
Photoautotrophs:
E source = Light
e.g. Photosynthesis using light energy and CO2 produces organic compounds
Producers form the base of all food chains
Phytoplankton are any small aquatic producers. E.g. Cyanobacteria as well as any photoautotrophic protists such as algae.
Terrestrial producers are largely made up of plants
Producers remove substantial amounts of CO2 from the atmosphere.
Prokaryotic Aquatic Producers
Bacteria and Archaea:
Cyanobacteria: Ancestors of this group were responsible for introducing oxygen into Earth’s atmosphere.
Archaean Thermophiles: Living near hot springs and deep sea thermal vents
Types of Eukaryotic Aquatic Producers
- Diatoms
- Green Algae
- Red Algae
- Brown algae
- Euglenids
1 to 4 is algae
- Diatoms
Unicellular algae
Brown/yellow photosynthetic pigment
Silica cell walls
Some contain oils that help them float.
Abundant in the ocean and freshwater lakes. and therefore use large quantities of atmospheric CO2.
The silica cell walls of dead diatoms take along time to degrade. Organic molecules within these cells is essentially trapped.
Accumulated dead diatoms on the ocean floor act as a large carbon sink as decomposers cannot access the organic molecules.
- Green Algae
Most green algae live in fresh water habitats. There are some marine varieties.
Unicellular varieties considered phytoplankton.
Some even live in damp soil.
Multicellular forms are typically anchored to the sediments by a hold fast.
- Red Algae
Most are multicellular, but not as large as brown algae.
Most abundant large algae in warm coastal waters (tropical oceans).
Red photosynthetic pigments mask the green ones.
Used for human consumption “Nori”. Makes the wrap around sushi.
Due to their red photosynthetic pigments, red algae can thrive in deeper waters as they can absorb blue and green light which penetrates far into the water.
- Brown Algae
The largest and most complex algae. All multicellular and marine, found along temperate coasts.
Large deep water varieties make up kelp forests which are home to many marine organisms.
Used for human consumption directly and gel forming substances from their cell walls used as a thickening agent in many foods.
- Euglenids
Unicellular
Mixotrophic (photoautotrophic or heterotrophic)
Green photosynthetic pigments
Flagella allow them to swim. Have a light detecting structure at the base of the flagella which allows them to move toward light for photosynthesis.
Eukaryotic Terrestrial producers Categories
Bryophytes, Gymnosperms, Seedless Vascular plants, Angiosperms.
Homologies between green algae and plants:
Evolution of the plants from common ancestor with green algae:
Same photosynthetic pigments (chlorophyll a & b) within chloroplasts
Store carbohydrates as starch
Have cell walls made of cellulose
5 Adaptations of terrestial plants:
Waxy Cuticle stomata vascular tissue pollen/seeds seeds protected by a fruit.
- Bryophytes
Primitive Characteristics: No true tissue No vascular system Small height (<5cm) Require a moist environment Require water for fertilization Produce spores
Adaptations for Land:
Waxy Cuticle
Stomata
No true tissue:
Bryophyte leaves have only 1 to a few cell layers. True tissue requires multiple layers of cells of different cell types.
Rhizoids (“roots”) only anchor the plant, no uptake of water or nutrients.
Bryophytes are tied to water because:
Cells making up bryophyte plants must obtain water through direct contact. There are no roots to take up water and no vascular system to distribute water throughout the plant.
Reproduction. Bryophytes have motile sperm which rely on water to swim through to get to the eggs for fertilization.
Waxy Cuticle:
Waxy Cuticle:
Covers surface of the cells of some species.
Prevents water loss
Stomata:
Stomata:
Pore on the surfaces of leaves created by 2 flanking guard cells.
Facilitate gas exchange & regulate evaporative water loss.
- Seedless Vascular Plants: Ferns, horsetails
Primitive Characteristics:
Require water for fertilization.
Produce spores.
New adaptations for Land:
Vascular tissue
True tissue
Seedless vascular plant adaptations
True tissue: leaves (blades), stem, and roots.
Vascular tissue: a system of vessels to distribute water, minerals and products of photosynthesis throughout the plant.
Allowed seedless vascular plants to be taller than bryophytes, but still rather short because of their dependence of water for fertilization.
Vascular Tissue: Xylem and Phloem
Xylem transports water and minerals absorbed by the roots up to the rest of the plant.
Phloem transports water and organic nutrients from the photosynthetic tissues to the rest of the plant (flow is in both directions).
- Gymnosperms:
New adaptations for land:
Sperm contained in pollen grains
Seeds instead of spores
Not dependent on water for reproduction! Wind dispersal used.
Conifers, Cycads, Ginkgos
Cones
Evergreen trees and shrubs (conifers) reproduce sexually through the production of cones bearing ovules and pollen (containing sperm).
Most commonly the same tree will produce both female and male cones.
Pollen is dispersed primarily by wind.
