Chapter 28: Protists (Part 2, Week 5) Flashcards
[Start 28.3 Nutritional and Defensive Adaptations]
T/F Adaptations extend past supergroups of protists.
True. Adaptions cross over many different supergroups.
What are the four ways that protists obtain nutrients?
Phagotrophy, osmotrophy, photoautotrophy, and mixotrophy.
How do heterotrophic (cannot produce its on food) protists feed?
What do you call an organism that feeds this way?
Ingesting particles, or phagocytosis. These are typically bigger particles.
Phagotroph - An organism that specializes in phagotrophy (particle feeding) by means of phagocytosis as a mechanism of nutrition.
Describe Osmotrophy.
What do we call organisms that feed this way?
How do they feed this way?
Protists that rely on osmotrophy—the uptake of small organic molecules across the cell membrane followed by their metabolism.
Osmotrophs - An organism that relies on osmotrophy (uptake of small organic molecules) as a mechanism of nutrition.
This is via osmosis where the diffusion of solvent molecules through a selectively permeable membrane.
Review: What do you call protists that feed on nonliving organic matter?
What about the opposite? (think cellular not a lion lel)
Decomposers - Essential in breaking down wastes and releasing minerals for use by other organisms.
Parasites - that feed on the living cells of other organisms that may cause disease. Humans view such protists as pests when they harm us or our agricultural animals and crops, but pathogenic protists also play important roles innature by controlling the population growth of other organisms.
What is an organism that uses the energy from light to make organic molecules from inorganic sources?
Photoautotroph (photosynthetic protists (algae))
Remember: Heterotrophs cannot make their own food, while autotrophs can. A photoautotroph makes its food from inorganic compounds such as sunlight (typically energy is not classified as such but you know).
Why have algae have evolved photosynthetic systems that compensate by capturing more of the blue-green light available underwater?
Because WATER absorbs much of the red component of sunlight.
Longer wavelengths such as red are absorbed at a shallower depth than shorter wavelengths such as blue, which penetrates to a deeper depth. Visible red light has slightly more energy than invisible infrared radiation and is more readily absorbed by water than other visible wavelengths
For example, red algae produce the red pigment phycoerythrin, which absorbs blue-green light and transfers energy to chlorophyll a.
Likewise, blue-green light-absorbing fucoxanthin generates the golden and brown colors of other algae.
Carotene (the source of vitamin A) and lutein play similar light-absorbing roles in green algae and were inherited by their land plant descendants, today playing important roles in animal nutrition.
How is sunlight energy captured which explains why algae of diverse types are good sources of food for aquatic animals and of renewable energy materials?
Captured in bonds if polysaccharide and liped molecules.
What is an organism that is able to use photoautotrophy as well as phagotrophy or osmotrophy to obtain organic nutrients?
Mixotroph
The genus Dinobryon, consisting of photosynthetic stramenopiles that live in the phytoplankton of freshwater lakes, is a mixotrophic genus.
These protists may switch back and forth between photoautotrophy and heterotrophy, depending on conditions in their environment. If sufficient light, carbon dioxide, and other minerals are available,
Dinobryon cells produce their own organic food.
If a shortage of any of these resources limits photosynthesis or if organic food is especially abundant, Dinobryon cells can function as heterotrophs, consuming enormous numbers of bacteria.
Mixotrophs thus have remarkable nutritional flexibility, explaining why many lineages of photosynthetic eukaryotes seem to have mixotrophic capability.
What are the major types of defenses that protists use to ward off attack? (4)
- Sharp projectiles explosively shot from cells
- Light flashes
- Toxic compounds
- Cell coverings
What do you call extruded bodies that are ejected when cells are disturbed, forming spear-like defenses?
Extrusomes
What is explained when some species of ocean dinoflagellates emit flashes of blue light when disturbed?
This explains why the ocean waters are teeming with there protists display bioluminescence.
The light flashes may deter herbivores by startling them, but when ingested, the dinoflagellates make the herbivores also glow, revealing them to hungry fishes.
Light flashes benefit dinoflagellates by helping to reduce populations of herbivores that consume the algae.
What are compounds that have adverse physiological effects in living organisms; often produced by various protist and plant species?
Toxins
Dinoflagellates are probably the most important protist toxin producers; they synthesize several types of toxins that affect humans and other animals.
Why do dinoflagellates produce so much many different types of toxins?
Under natural conditions, small populations of dinoflagellates produce low amounts of toxin that do not harm large organisms.
Dinoflagellate toxins become dangerous to humans when people contaminate natural waters with excess mineral nutrients such as nitrogen and phosphorus from untreated sewage, industrial discharges, or fertilizer that washes off agricultural fields.
What does the excess nutrients from runoff of human waste fuel the development of?
Harmful algal blooms, which then produce sufficient toxin to affect birds, aquatic mammals, fishes, and humans.
Toxins can become concentrated in organisms. Humans who ingest shellfish that have accumulated dinoflagellate toxins can suffer poisoning.
