How can we help?

You can also find more resources in our Help Center.

Ch. 28 Biology

STUDY
PLAY
Protist
any eukaryote that is not a plant, animal, or fungus. Most protists are unicellular
Mixotrophs
Combine photosynthesis and heterotrophic nutrition
Secondary Endosymbiosis
A process in eukaruotic evolution in which a heterotrophic eukaryotic cell engulfed a photosynthetic euk. cell, which survived in a symbiotic relationship inside the heterotrophic cell.
Five Supergroups
Excavata, Chromalveolata, Rhizaria, Archaeplastida, Unikonta
Excavata
Groove on one side (some have modified mitochondria)
Chromalveolata
May have originated by sec. endosymbiosis; includes some of the most important photsynthetic organisms on earth.
Rhizaria
Species of amoeba which have pseudopodia (used in movement)
Archaeplastida
include red and green algae
Unikonta
includes amoebas that have lobe- or tube- shaped pseudopodia
Cite 4 examples of structural and functional diversity among protists.
-unicellular, colonial, or multicellular
-photoautotrophs, heterotrophs, and mixotrophs
-produce asexually, sexually, or both
-diverse physical forms and adaptations
Summarize the role of endosymbiosis in eukaryotic evolution
strong evidence shows that eukaryotes acquired mitochondria after an early eukaryote first engulfed and then formed an endosymbiotic association with an alpha proteobacterium. Sililarly, chloroplasts in red and green algae appear to have descended from a photsynthetic cyanobacterium that was engulfed by an ancient hetertrophic eukaryote. SEcondaru endosymbiosis also played an important role: Various protist lineages acquired plastids by engulfing unicellular red or green algae.
Why do some biologists describe the mitochondria of diplomonads and parabasalids as "highly reduced?"
Their mitochondria do not have an electron trasnport chain and so cannot funciton in aerobic respiration.
Alternation of Generations
the alternation of multicellular haploid and diploid forms.
Heteromorphic
the sporophytes and gametophytes are structurally different
Isomorphic
the s-phytes and g-phyts look similar, but differ in chromosome number
Protists that are surrounded by more than two membranes are evidence of:
a. evolution from mitochondria
b.fusion of plastids
c. origin of the plastids from archaea
d. secondary endosymbiosis
e. budding of the plastids from the nuclear envelope
d. secondary endosymbiosis
Biologists suspect that endosymbiosis gave rise to mitochondria before plastids because:
all eukaryotes have mitochondria (or their remnants) whereas many eularyotes do not have plastids
Which group is incorrectly paired with its description:
a. rhizarians- morphologically diverse group define by dna similarities
b. diatoms- important producers in aquatic communities
c. red algae- acquired plastids by secondary endosymbiosis
d. apicomplexans- parasites with intricate life cycles
e. diplomonads- protists with modified mitochondria
red algae did not acquire plastids by secondary endosymbiosis
Which protists are in the same eukaryotic supergroup as land plants?
green and red algae
In life cycles with an alternation of generations, multicellular haploid forms alternate with
multicellular diploid forms.