BIO CRAM NOTES 3

Which of the following is true of secondary endosymbiosis?

It is indicated by the presence of a double membrane surrounding the endymbiont.
An organism containing one endosymbiont engulfs another organism, and that organism becomes an endosymbiont.
It is indicated by the presence of a nucleomorph.
An organism containing an endosymbiont is engulfed by another organism and becomes an endosymbiont.
It is indicated by the presence of a mixotroph.

A sign on the beach states, “Beach Closed. Red Tide.” The organisms interfering with your use of this beach are probably _____.
amoebas
ciliates
diatoms
dinoflagellates
species of red algae

Which of the following is a correct statement about cellular slime molds?

Cellular slime molds have haploid zygotes.
Cellular slime molds have fruiting bodies that function in sexual reproduction.
Cellular slime molds form masses when food is scarce, but their cells remain separated.
Cytoplasmic streaming helps distribute nutrients and oxygen in cellular slime molds.

Why has the kingdom Protista been abandoned?

Some protists are multicellular.
The kingdom Protista is polyphyletic.
Some protists are more closely related to plants, animals, or fungi than they are to other protists.
Some protists are as small as prokaryotes.
The second and third answers are correct.

Coral bleaching, which causes high coral mortality, has been occurring widely in coral reefs. Coral bleaching actually refers to the death of symbiotic dinoflagellates living within the corals. Why does coral bleaching cause the corals to die?

Dinoflagellates protect the corals from UV radiation.
Dinoflagellates protect the corals from pathogenic bacteria.
Dinoflagellates provide nutrients from the products of photosynthesis to the corals in exchange for a safe place to live.
Dinoflagellates attract zooplankton and other prey that the corals eat.
Dinoflagellates secrete the calcium carbonate that forms the “exoskeleton” of coral animals.

Miller and Urey’s experiments that attempted to recreate conditions on early Earth were significant because _____.

they showed that organic molecules such as amino acids could be produced from inorganic molecules
they showed how polymers could form spontaneously on a clay substrate
they produced the first protocells
they showed how radiometric dating could be used to give the absolute ages of rocks and fossils
proved the endosymbiotic theory

According to the endosymbiotic theory of the origin of eukaryotic cells, how did mitochondria originate?

from infoldings of the plasma membrane, coupled with mutations of genes for proteins in energy-transfer reactions
from engulfed, originally free-living proteobacteria
by secondary endosymbiosis
when a protoeukaryote engaged in a symbiotic relationship with a protocell
from the nuclear envelope folding outward and forming mitochondrial membranes

Which of the following was derived from an ancestral cyanobacterium?

mitochondrion
chloroplast
mitosome
hydrogenosome
Two of the responses above are correct.

In a sample of pond water, a new organism is identified with the following characteristics: It consists of 70 cells surrounded by rigid cell walls, which join the cells together. Inside each of these identical cells are mitochondria and chloroplasts. Such an organism would most likely be classified as a

multicellular photosynthetic prokaryote.
fungal photosynthetic eukaryote.
colonial photosynthetic eukaryote.
colonial eukaryotic fungus.
colonial photosynthetic prokaryote.

The evolution of multicellularity in animals required adaptations that promoted

cellular adhesion and intercellular communication.
cellular migration and intercellular communication.
cellular fusion and regeneration.
photosynthesis and cellular migration.
cellular migration and cellular adhesion.

Which of the following are two groups that are adapted to anaerobic conditions and contain reduced mitochondria that lack DNA?

dinoflagellates and diatoms
chlorophytes and radiolarians
apicomplexans and forams
gymnamoebas and slime molds
diplomonads and parabasalids

Archaeplastids, which include red and green algae and land plants, are thought to have descended from a heterotrophic protist that engulfed a(n) _____.

slime mold
alpha proteobacterium
cyanobacterium
apicomplexan
archaean extremophile

include prokaryotic autotrophs that float near the surface of water and are the basis of the food chain.

Zooplankton
Slime molds
Phytoplankton
Cyanobacteria
Symbionts

Why do some scientists believe that RNA, rather than DNA, was the first genetic material?

RNA can replicate more accurately than DNA.
RNA could have evolved into DNA.
RNA has both information storage and catalytic properties.
All the proto-cells on early Earth contained RNA.
RNA contains uracil in place of thymine

Which group is INCORRECTLY paired with its description?

rhizarians–morphologically diverse group that includes amoebas with threadlike pseudopodia
diatoms–important producers in aquatic communities
red algae–acquired plastids by secondary endosymbiosis
apicomplexans–parasites with intricate life cycles
diplomonads–protists with modified mitochondria

The evolution of complex multicellularity in eukaryotes

occurred only once, in the common ancestor of all multicellular eukaryotes.
occurred only once, in the common ancestor of all eukaryotes.
occurred only once, in the animal lineage.
is not documented by the fossil record.
occurred independently in several different eukaryotic lineages.

Plastids that are surrounded by more than two membranes are evidence of

secondary endosymbiosis.
evolution from mitochondria.
fusion of plastids.
origin of the plastids from archaea.
budding of the plastids from the nuclear envelope.

Biologists think that endosymbiosis gave rise to mitochondria before plastids partly because

mitochondrial DNA is less similar to prokaryotic DNA than is plastid DNA.
all eukaryotes have mitochondria (or their remnants), whereas many eukaryotes do not have plastids.
mitochondrial proteins are synthesized on cytosolic ribosomes, whereas plastids utilize their own ribosomes.
the products of photosynthesis could not be metabolized without mitochondrial enzymes.
without mitochondrial CO2 production, photosynthesis could not occur.