BIO 117 EXAM 2

The leading hypothesis to explain the origin of the nuclear envelope is based on infoldings of the plasma membrane.

• True

• False

According to the endosymbiosis theory, what type of organism is the original ancestor of the chloroplast?

• a photosynthetic archean

• a cyanobacterium

• an algal-like, primitive eukaryote

• a modified mitochondrion

All protists have cell walls

• True

• False

Which is a characteristic of all protists

• All protists are photosynthetic

• All protists are prokaryotic

• All protists are eukaryotic

• All protists are multicellular

• All protists grow as colonies

Which statement correctly describes secondary endosymbiosis?

• A protist engulfs two types of bacteria.

• A protist engulfs a bacterium.

• A photosynthetic protist is engulfed by another protist.

• A bacterium reproduces inside a protist.

• Two protists exchange symbiotic genes.

Consider the endosymbiotic theory for the origin of the mitochondrion.  The relationship between the two organisms was considered to be stable because a mutual advantage existed between them: The host cell provided the bacterium _______ while the bacterium provided the host cell ______. 

• ATP; protection and carbon compounds

• Protection and carbon compounds; ATP

• ATP; oxygen

• oxygen; carbon compounds

What evidence exists for the secondary endosymbiotic theory?

• Certain protists contain organelles that are enclosed in four layers of membranes. This indicates secondary endosymbiosis.

• All protists have plastids.

• The mitochondria of all protists have two membranes.

• Not all protists have mitochondria.

• All answers are correct.

Which statement about the importance of protists to the ocean ecosystems is correct?

• Protists are extremely important because many are primary producers sitting at the base of the food web.

• Protists are somewhat important because they bring energy only to shallow ocean regions.

• Protists are not very important because as single-celled organisms, they do not affect the ocean significantly.

• Protists are not important at all because they do not consume any other organisms.

• None of the answers are correct.

Are protists a mono- or paraphyletic group? Why?

• Monophyletic, because all members of the group share the trait of being eukaryotic

• Monophyletic, because the group represents an ancestor and ALL of the descendants

• Paraphyletic, because members of the group have extremely diverse traits

• Paraphyletic, because the group represents an ancestor and SOME (but not all) of the descentants

Examples of both asexual and sexual reproduction can be seen among protists.  Some species can even switch between asexual and sexual cycles.

• True

• False