Chapter 25

Chloroplasts are thought to have originated from a symbiotic relationship between an ancient eukaryotic cell and:

A cyanobacterium

Which statement correctly describes the relationship among species in a phylogenetic tree?

Species with only one branch point separating them are more closely related than species with more than one branch separating them

All of the membranes in the eukaryotic fell are in dynamic continuity except for membranes in the:

Mitochondria and chloroplasts

In plasmodia slime molds, what structure is responsible for producing the haploid cells that disperse into the environment?


In animals, the egg and sperm cells are:


Chloroplasts and mitochondria in eukaryotes are thought to have originated by ____, wherein one organism lives inside another.


Which of the statements regarding diatoms is false?

Most diatoms are multicellular eukaryotes

Which of the features is responsible for the evolutionary success of eukaryotes?

Possessing a dynamic cytoskeleton, having complex patterns of gene regulation, localizing where energy metabolism takes place, and possessing a dynamic endo membrane system

Green algae are most closely related to:

land plants

The term protist lacks phylogenetic accuracy because it represents a paraphyletic group. Which of the statements reflects the paraphyly of protist taxa?

Some eukaryotic lineages evolved from protists, and they are not included in the group called protists.

Which of the statements describes characteristics of eukaryotic cells but not prokaryotic cells?

Relatively large genome, dynamic cytoskeleton, compartmentalized metabolic processes

What components of eukaryotic cells leave a fossil record?

Cell walls

Which of the seven superkingdoms contains all photosynthetic organisms?


Which of the statements is evidence supporting the hypothesis that eukaryotic chloroplasts originated from Cyanobacteria?

Chloroplasts and Cyanobacteria have similar DNA sequences for shared genes.

Many single-celled have evolved complex life cycles that include sexual reproduction. This means that:

Two cells, at some point, must fuse to become diploid

Which of the statements is false regarding protists?

They are a monophyletic group of organisms

A cell with chloroplasts that have four membranes (not counting the thylakoid membranes) likely arose by _____ endosymbiotic event(s).


The diversity of shapes found in eukaryotic cells is made possible by the:


To which superkingdom do corn and wheat belong?


Sexual fusion brings two haploid cells together to produce a ____ cell.


A symbiont is an organism that lives in close association with another species.


What structure is found in all members of the superkingdom Stramenopila?

A flagellum with stiff hairs

Which is the oldest group of eukaryotes to be recognized in the fossil record?

Red algae

Which of the statements accounts for why eukaryotic cells are typically much larger than prokaryotic cells?

Using molecular motors, eukaryotic cells can transport materials throughout their cytoplasm much faster than prokaryotic cells can; prokaryotic cells have to rely on simple diffusion

There is no known synopsis between a heterotrophic host and a photosynthetic partner in mammals.


Photosynthesis spread through eukaryotes by repeated endosymbiosis involving eukaryotic algae


In eukaryotes that lack mitochondria, what structures are present to generate ATP for cellular use?


Diatoms appeared during the Mesozoic Era, and the skeletons of these organisms contributed to the accumulation of sediments of the deep sea floor.


The majority of prokaryotic DNA is arrayed in:

A single circular chromosome

Choanoflagellates are the closest protistan relatives of animals


A young paleontologist is extremely excited. I'm sedimentary rocks dating from 70 million years ago, she has found some new microfossils. The shells of which organisms likely contributed to the accumulation of sediments on the sea floor (and the formation

Foraminiferans, diatoms, radiolarians, and coccolithophorids

Eukaryotes have more ways to obtain energy than prokaryotes


Organelles have their own genomes. When chloroplast DNA is sequences and compares to genomes from members of the Cyanobacteria, the chloroplast DNA sequence is nested within the genomes of Cyanobacteria. This is strong evidence for the hypothesis that:

The chloroplast originated as a symbiotic Cyanobacteria that became permanently incorporated into its host

Which superkingdom contains members that are responsible for forming red tides?


Which of the statements is a key advantage of eukaryotic cells over prokaryotic cells?

Eukaryotic cells have a flexible cytoskeleton, which allows them to change shape and gives them the ability to engulf other materials.

You are in a lab studying a newly discovered cell type. You observe a rigid cytoskeleton in this cell, along with a nucleus and a compartmentalized interior. How would you classify this cell?

As a possible transitional cell changing from prokaryotic to eukaryotic

To which of the super kingdoms do diatoms belong to?


You have learned that having linear DNA had consequences, the major one being that the DNA is shortened every time it replicated. This does not happen with the circular DNA found in prokaryotes. What, then, is the advantage of having linear DNA?

Replication can begin from multiple sites on the linear DNA, allowing rapid replication and relieving the evolutionary pressure for a streamlined genome.

How do eukaryotic cells generate and maintain genetic diversity?

Through sexual reproduction

Which of the statements is a hypothesis to explain the origin of the modern eukaryotic cell?

A cell evolved a nucleus first, then incorporated a proteobacterial cell that became a mitochondrion.

Imagine that a researcher discovers a new type of organelle in single-celled eukaryotes. She suspects that this new organelle is the result of endosymbiosis. How could she support this theory?

She could determine whether this organelle has both an inner or outer membrane, she could use electron microscopy to determine if any structural similarities exist between this new organelle and prokaryotic cells (such as whether it is similar to proteoba

Which of the answer choices is the best description of a protozoan?

A heterotrophic protist

Chloroplasts originated from endosymbiotic Cyanobacteria once and only once


The genes in chloroplasts more closely match the genes found in Cyanobacteria as compared to the genes found in the nuclei of photosynthetic eukaryotes.


The terms 'algae' and 'protozoa' have significant phylogenetic meaning.


The current theory is that chloroplasts are descendants of symbiotic Cyanobacteria that lived within eukaryotic cells. If we look at the respective genomes, however, we see that the Cyanobacteria have many more genes than do chloroplasts. Where did the Cy

Many of the genes were transported to the nucleus, and others were lost.

In which group of archaeplastids are the chloroplasts most similar to those of the ancestral Cyanobacterial endosymbiont?


The photosynthetic amoeba Paulinella is an example of a second chloroplast endosymbiotic event involving a Cyanobacterium.


Photosynthetic protists are informally referred to as:


Which of the answer choicesf is the best description of algae?

A photosynthetic protist

Most eukaryotic cells contain mitochondria, but a few single-celled eukaryotic organisms found it oxygen-free environments do not. Which of the observations led biologists to reject the hypothesis that these mitochondria-free eukaryotes evolved before the

The nuclear genome of these mitochondria-free eukaryotes contains relics of mitochondrial genes.

How does current theory explain the origin of a nucleus in eukaryotic cells?

While there are some competing theories on the origin of the nucleus, neither theory discussed in the text really explains the origin of the nucleus.

Chloroplasts are thought to have evolved from:


To which of the superkingdom do jellyfish belong?


Chloroplasts and mitochondria in eukaryotes are thought to have originated by ____, wherein on organism lives inside another