13 - Protists 2* Flashcards
Primary production
The production of organic compounds from carbon dioxide (carbon fixation) is predominantly by photosynthesis.
Most life on earth is reliant on organisms that carry out primary production
What are the primary producers of the ocean
Photosynthetic protists and bacteria
Primary producers of terrestrial environments
Plants
Microalgae
Photosynthetic protists
Photoautotrophs
Only occur where sufficient light penetrates, above the continental shelf due to attachment to ground
Food chain
The sequence of predators and prey in a biological community.
The trophic level of an organism is the position it holds in a food chain
zooplankton
Primary consumer. key link between primary producers and secondary consumers in aquatic ecosystems
example of mutualistic symbiosis in protists
Reef-building corals harbor photosynthetic endosymbiotic protists termed zooxanthellae, which satisfy most of their energy requirements and in return receive nitrogenous compounds
Termite protists and wood recycling
Termites seem to produce some of the
enzymes needed to start cellulose
digestion, but there appears to be no
termite enzymes that can complete
cellulose digestion.
Trichonympha is one of several genera of
protists that live in the intestines of many, if
not most, termite species.
Trichonympha does not directly digest the
wood, but its gut provides a home for
bacterial endosymbionts that produce
cellulose-degrading enzymes.
The slime mould symbiosis `
(Amoebozoa: Eumycetozoa)
Slime moulds contribute to the
decomposition of dead vegetation,
and feed (by phagocytosis) on
particles, bacteria, yeasts and fungi in
soils
Malaria
- Primarily tropical disease caused by several Plasmodium species.
- Major symptoms include fever, shaking chills, headache, muscle aches, tiredness and death.
- Parasite is mosquito-borne (Anopheles spp)
- Drug-resistant malaria well established in Africa, Asia and S. America
- Only needs one sporozoite to cause disease as liver cells produce thousands and spread to RBCs know life cycle fam
African Tryanosomiasis
- Trypanosoma brucei gambiense, Trypanosoma brucei rhodesiensie - transmitted by tsetse fly into the blood
- African sleeping sickness (a symptom of CNS invasion)
- necrosis (cell death) of lymph system, heart, brain, CNS (neurological effects)
- personality changes, daytime sleepiness with night time sleep disturbance, and progressive confusion
- located central africa
explain the contribution of protists to human demographics
Phytophthora infestans destroyed the
European potato crop in the mid1840s (‘potato blight’), spawning the
Great Irish famine.
-1845–57: > 1 million starved to death
and another 1-2 million emigrated
- accounts for a large proportion
of US citizens of Irish descent
explain the contribution of protists to geology
Foraminifera (‘forams’)
- amoeboid, mostly marine, protists
- form ornate shells (‘test’) of calcium
carbonate
- pseudopodia extrude through pores to
capture microscopic prey in outside environment
- foram tests (dead forams) make up most modern-day deposits of chalk, limestone, and marble
explain the contribution of protists to climate
Marine phytoplankton produce ‘osmoregulators’, chemicals that help control the dehydrating effects of life in a salty environment
On release (lysis, excretion), volatile DMS (Dimethyl sulfide) is produced from these
chemicals by bacteria and enters the atmosphere, where it acts as nuclei for cloud
droplet formation
Thus, phytoplankton protists (microalgae)
influence global weather patterns by influencing cloud formation over the ocean (70% of the earth’s surface)
