Chapter 28 quiz questions/chapter questions Flashcards
The chloroplasts of land plants are thought to have been derived according to which evolutionary sequence?
cyanobacteria → green algae → land plants
red algae → brown algae → green algae → land plants
cyanobacteria → green algae → fungi → land plants
cyanobacteria → red algae → green algae → land plants
cyanobacteria → green algae → land plants
All protists are ________.
mixotrophic
symbionts
unicellular
eukaryotic
eukaryotic
Many parasitic members of the excavates lack plastids and have highly reduced mitochondria. Which of the following statements explains these observations?
The original, eukaryotic ancestors of these parasites did not engulf prokaryotes.
These parasites live in dark, low-oxygen conditions, and therefore it was adaptive to move all plastid and mitochondrial genes to the nucleus.
These parasites live in dark, low-oxygen conditions and therefore loss of genes for plastids and mitochondria did not result in lower fitness.
In the future, natural selection will favor descendants that acquire new plastid genes from today’s prokaryotes.
These parasites live in dark, low-oxygen conditions and therefore loss of genes for plastids and mitochondria did not result in lower fitness.
When a mosquito infected with Plasmodium first bites a human, the Plasmodium ________.
gametes fuse, forming an oocyst
cells cause lysing of the human red blood cells
oocyst undergoes meiosis
cells infect the human liver cells
cells infect the human liver cells
Which of the following pairs of protists and their ecological roles are correctly matched?
euglenozoans—primarily mixotrophic
apicomplexans—parasites of animals
entamoebas—free-living soil organisms
dinoflagellates—parasites of plants
apicomplexans—parasites of animals
Dinoflagellates ________.
possess two flagella
include species that cause malaria
lack mitochondria
are all autotrophic
possess two flagella
You are given an unknown organism to identify. It is unicellular and heterotrophic. It is motile, using many short extensions of the cytoplasm, each featuring the 9 + 2 filament pattern. It has well-developed organelles and two nuclei, one large and one small. This organism is most likely to be a ________.
diatom
ciliate
rhizarian
alveolate
ciliate
A biologist discovers an alga that is marine, multicellular, and lives at a depth reached only by blue light. This alga is most likely a type of ________.
blue algae- duh
green algae
red algae
brown algae
red algae
The fact that amoebas are not monophyletic demonstrates that ________.
movement by pseudopodia evolved only once
scientists need to continue to investigate the origins and evolutionary history of protists
evolutionary history cannot be discovered
eukaryotes are also not monophyletic and need to be broken into many groups
scientists need to continue to investigate the origins and evolutionary history of protists
SAR is a group defined by DNA similarities. This grouping represents ________.
a hypothesis about evolutionary history
a paraphyletic group
a demonstration that DNA similarities cannot reveal evolutionary history
a catch-all group that links many unrelated organisms
a hypothesis about evolutionary history
Cite four examples of structural and functional diversity among protists
Protists include unicellular, colonial, and multicellular organisms; photoautotrophs, heterotrophs, and mixotrophs; species that reproduce asexually, sexually, or both ways; organisms with diverse
physical forms and adaptations.
Summarize the role of endosymbiosis in eukaryotic evolution
Strong evidence shows that eukaryotes acquired mitochondria after a host cell (either an archaean or a close relative of the archaeans) first engulfed and then formed an endosymbiotic association
with an alpha proteobacterium. Similarly, chloroplasts in red and green algae appear to have descended from a photosynthetic cyanobacterium, that was engulfed by an ancient heterotrophic
eukaryote. Secondary endosymbiosis also played an important role: various protist lineages acquired plastids by engulfing unicellular red or green algae.
Would you expect the plastid DNA of photosynthetic dinoflagellates, diatoms, and golden algae to be more similar to the nuclear DNA of plants (Domain Eukarya) or the chromosomal DNA of cyanobacteria (Doman Bacteria)? Explain.
The plastid DNA would likely be more similar to the chromosomal DNA of cyanobacteria based on the well-supported hypothesis that eukaryotic plastids (such as those found in eukaryotic groups
listed) originated by an endosymbiosis event in which a eukaryote engulfed a cyanobacterium. If the plastid is derived from the cyanobacterium, its DNA would be derived from bacterial DNA.
Justify the claim that photosynthetic protists are among the biosphere’s most important organisms
Because photosynthetic protists constitute the base of aquatic food webs, many aquatic organisms depend on them for food, whether directly or indirectly. In addition, a substantial percentage of the
oxygen produced by photosynthesis is made from photosynthetic protists.
Describe three symbioses that include protists.
Protists form mutualistic and parasitic associations with other organisms. Examples include photosynthetic dinoflagellates that form a mutualistic symbiosis with coral polyps, parabasalids that form a mutualistic association with termites, and the stramenopile, Phytophthora ramorum, a parasite of oak trees.
