Question 1

Photosynthetic eukaryotes have genes for rRNA in their nuclei, mitochondria, and chloroplasts.Based on what you know about the origins of mitochondria and chloroplasts, which of the statements below would best describe the evolutionary relationship between the rRNA genes found in these three organelles?
A) Nuclear and mitochondrial rRNA are derived from close relatives; however, both are distant from chloroplast rRNA.
B) Mitochondrial and chloroplast rRNA are derived from close relatives; however, both are distant from nuclear rRNA.
C) Nuclear and chloroplast rRNA are derived from close relatives; however, both are distant from mitochondrial rRNA.
D) Mitochondrial, chloroplast, and nuclear rRNA are all derived from distant relatives.
E) There is no reason to assume that any of the three rRNA genes are similar to closely or distantly related relatives.

Accepted Answer

The answer of Photosynthetic eukaryotes have genes for rRNA in...

Question 2

Which group contains multicellular brown algae and giant kelps?
A) Diplomonads
B) Chlorophytes
C) Stramenopiles
D) Alveolates
E) Euglenids

Accepted Answer

Stramenopiles contain multicellular brown algae and giant kelps. Diplomonads, Chlorophytes, Alveolates, and Euglenids do not contain these organisms.

Question 3

Which statement about protists is false?
A) Most protists are found in terrestrial habitats.
B) Protists have many different metabolic lifestyles.
C) Protists use pseudopods, cilia, or flagella for locomotion.
D) Several groups of protists use contractile vacuoles to rid themselves of excess water.
E) Many protists are photosynthetic.

Accepted Answer

Most protists are found in aquatic habitats, not terrestrial habitats.

Question 4

Alveolates typically
A) have two unequal flagella, one of which has hairs.
B) possess long, thin pseudopods.
C) have lobe-shaped pseudopods.
D) possess sacs just beneath their plasma membranes.
E) lack mitochondria.

Accepted Answer

Alveolates possess small sacs called alveoli that lie just beneath their plasma membranes. These sacs provide support for the cell and help maintain its shape.

Question 5

Which group can produce a toxin in marine environments that accumulates in clams, mussels, and oysters and can cause paralytic shellfish poisoning?
A) Red algae
B) Radiolarians
C) Diatoms
D) Euglenids
E) Dinoflagellates

Accepted Answer

Dinoflagellates can produce a toxin in marine environments that accumulates in clams, mussels, and oysters, which can cause paralytic shellfish poisoning.

Question 6

Plasmodium, the organism that causes malaria, has a mass of organelles at the tip of the cell that enables it to enter cells in the human body.This characteristic suggests that Plasmodium is a member of the
A) alveolates.
B) stramenopiles.
C) apicomplexans.
D) choanoflagellates.
E) rhizarians.

Accepted Answer

The mass of organelles at the tip of the cell that enables Plasmodium to enter cells in the human body is known as the apical complex. This is a defining characteristic of apicomplexans, of which Plasmodium is a member. Alveolates (A) and stramenopiles (B) do not possess this feature, and choanoflagellates (D) and rhizarians (E) are not related to Plasmodium or apicomplexans.

Question 7

When ancestral photosynthetic euglenids obtained their chloroplasts, the result was a chloroplast surrounded by three membranes.This is evidence of acquisition of the chloroplast by
A) primary endosymbiosis.
B) secondary endosymbiosis, retaining the chloroplast from a green alga.
C) secondary endosymbiosis, retaining the chloroplast from a plant.
D) tertiary endosymbiosis.
E) quaternary endosymbiosis.

Accepted Answer

The presence of three membranes around the chloroplast is indicative of secondary endosymbiosis, where a eukaryotic cell engulfs another eukaryotic cell that already contains a chloroplast. In the case of photosynthetic euglenids, the chloroplasts were acquired through the engulfment of a green alga.

Question 8

Dinoflagellates are common endosymbionts of
A) coral.
B) fungi.
C) other dinoflagellates.
D) tertiary endosymbionts.
E) stramenopiles.

Accepted Answer

Dinoflagellates commonly form a mutualistic relationship with coral, providing them with photosynthesis products and aiding in calcium carbonate deposition. They can also be harmful to coral in the case of coral bleaching, where they produce toxins that harm the coral.

Question 9

Which diseases are caused by apicomplexans?
A) Giardiasis and toxoplasmosis
B) Malaria and giardiasis
C) A human sexually transmitted disease and toxoplasmosis
D) Malaria and a human sexually transmitted disease
E) Malaria and toxoplasmosis

Accepted Answer

Apicomplexans are a group of protists that includes the organisms responsible for causing malaria (Plasmodium species) and toxoplasmosis (Toxoplasma gondii). Giardiasis is caused by a different type of protist called Giardia lamblia. There are no apicomplexans that are known to cause sexually transmitted diseases in humans.

Question 10

Refer to the diagram, which shows the role of vacuoles in ciliate digestion.  The figure illustrates an experiment designed to determine whether Paramecium digests food in an acidic environment.This organism most likely _______ and is _______.
A) is free-swimming with cilia; heterotrophic
B) is free-swimming with flagella; heterotrophic
C) is free-swimming with flagella; autotrophic
D) moves by floating in plankton; autotrophic
E) is free-swimming with cilia; autotrophic

Accepted Answer

The diagram shows ciliates, specifically Paramecium, which are a type of free-swimming protozoan with cilia used for locomotion. The diagram also shows food being taken in by phagocytosis and moved to the vacuole for digestion, indicating that Paramecium is heterotrophic (obtains nutrients by consuming other organisms). The other answer choices are incorrect based on the information provided.

Question 11

What would be a plausible outcome if cats developed a resistance to Toxoplasma?
A) Cats would no longer display a fear of dogs, because Toxoplasma would be unable to complete its life cycle and infect new cats.
B) Cats would remain afraid of dogs, because Toxoplasma would be unable to complete its life cycle and infect new cats.
C) Rats would no longer display a fear of cats, because Toxoplasma would be unable to complete its life cycle and infect new rats.
D) Rats would remain afraid of cats, because Toxoplasma would be unable to complete its life cycle and infect new rats.
E) There would be no change in the behavior of infected rats or cats.

Accepted Answer

If cats developed a resistance to Toxoplasma, the parasite would be unable to complete its life cycle, which involves infecting rats and altering their behavior to reduce fear of cats. Without this alteration, rats would remain afraid of cats.

Question 12

Which of the following represents the synapomorphy of the stramenopiles?
A) The presence of peptidoglycan between membranes of a chloroplast
B) Rows of tubular hairs on the longer of two flagella of unequal size
C) Air sacs below the plasma membrane
D) A fully parasitic lifestyle
E) External shells of calcium carbonate

Accepted Answer

Rows of tubular hairs on the longer of two flagella of unequal size, known as heterokont flagella, is a synapomorphy of the stramenopiles.

Question 13

Which statement does not apply to apicomplexans?
A) They are parasites. 
B) They have complex life cycles.
C) They lack contractile vacuoles.
D) Each has an apical mass of organelles that helps it enter hosts.
E) Each possesses small sacs just below its cell membrane.

Accepted Answer

All statements except E apply to apicomplexans. Apicomplexans have a complex life cycle, lack contractile vacuoles, and have an apical mass of organelles that helps them enter hosts. They are also parasites. However, they do not possess small sacs just below their cell membrane.

Question 14

Which statement about microbial eukaryotes is false?
A) Multicellular groups evolved from microbial eukaryotes.
B) Photosynthetic microbial eukaryotes play a major role in the energy balance of the living world.
C) There are no parasitic forms of microbial eukaryotes.
D) Saprobic microbial eukaryotes are among the important decomposers and thus play a major role in the nutrient cycles of the living world.
E) Many microbial eukaryotes have highly differentiated bodies, even though they consist of only one cell.

Accepted Answer

There are parasitic forms of microbial eukaryotes, such as certain types of protozoa and fungi.

Question 15

Dinoflagellates possess sacs beneath their plasma membranes and chloroplasts that contain pigments that give them a golden brown color.Dinoflagellates are therefore classified as
A) stramenopiles.
B) green algae.
C) red algae.
D) alveolates.
E) euglenids.

Accepted Answer

Dinoflagellates are classified as alveolates because of the presence of alveoli, which are sac-like structures located beneath their plasma membranes. This characteristic feature, along with their unique pigments in chloroplasts, distinguishes them from other groups.

Question 16

You are watching a Paramecium in fresh water and see a rounded structure within it enlarge and then suddenly contract as water is expelled.You have just witnessed the
A) food vacuole releasing excess water acquired through eating.
B) oral groove expelling water as food is ingested.
C) result of ciliary action involved in locomotion.
D) contractile vacuole keeping the organism's cytoplasm hypertonic to the environment.
E) expulsion of waste produced during digestion.

Accepted Answer

The description given - a rounded structure within the Paramecium enlarging and then suddenly contracting as water is expelled - describes the function of a contractile vacuole. Contractile vacuoles help regulate the osmotic balance of the Paramecium by expelling excess water and keeping the cytoplasm hypertonic to the environment.

Question 17

When organic material is digested in a food vacuole, the pH in the vacuole
A) decreases to aid in digestion, and then increases as digestion is completed.
B) increases to aid in digestion, and then decreases as digestion is completed.
C) stays the same during and after digestion.
D) stays the same during digestion, and then increases as digestion is completed.
E) increases or decreases depending on the material consumed.

Accepted Answer

When organic material is digested in a food vacuole, enzymes are released into the vacuole, which lowers its pH (making it more acidic) to aid in the breakdown of the material. After digestion is completed, the pH increases back to its original level. This process is similar to how stomach acid aids in the digestion of food in humans and animals.

Question 18

Refer to the figure.  This phylogenetic tree shows one current hypothesis and estimated time line for the origin of the major groups of eukaryotes.Which clade of eukaryotes was the first to diverge from other eukaryotes?
A) Alveolates
B) Rhizarians
C) Excavates
D) Amoebozoans
E) Plantae

Accepted Answer

The answer of Refer to the figure.  This phylogenetic...

Question 19

Many dinoflagellates are _______ that have _______.Most live in _______.
A) ciliates; chloroplasts; the oceans 
B) endosymbionts; two flagella; the oceans
C) stramenopiles; two flagella; rivers
D) endosymbionts; cilia; rivers
E) endosymbionts; two flagella; rivers

Accepted Answer

Dinoflagellates are endosymbionts (living in a symbiotic relationship with another organism) that have two flagella. Most of them live in the oceans. Choice A is incorrect because dinoflagellates do not have cilia, but rather flagella. Choice C is incorrect because stramenopiles are a separate group of organisms. Choice D is incorrect because dinoflagellates do not have cilia.

Question 20

Refer to the diagram, which shows the role of vacuoles in ciliate digestion.  Which of the following is a plausible hypothesis to explain why the vacuole color returns to red?
A) The pH returns to basic because of increasing proton concentration. 
B) The pH returns to basic because of decreasing proton concentration.
C) The dye from all food vacuoles coalesces into one vesicle destined for exocytosis.
D) Multiple food vacuoles at different stages of digestion fuse into a single vesicle.
E) The pH returns to acidic because of an increase in salt concentration.

Accepted Answer

The answer of Refer to the diagram, which shows the...

Quiz 26: The Origin and Diversification of Eukaryotes

Which group contains multicellular brown algae and giant kelps?

Which statement about protists is false?

Alveolates typically

Which group can produce a toxin in marine environments that accumulates in clams, mussels, and oysters and can cause paralytic shellfish poisoning?

Plasmodium, the organism that causes malaria, has a mass of organelles at the tip of the cell that enables it to enter cells in the human body.This characteristic suggests that Plasmodium is a member of the

When ancestral photosynthetic euglenids obtained their chloroplasts, the result was a chloroplast surrounded by three membranes.This is evidence of acquisition of the chloroplast by

Dinoflagellates are common endosymbionts of

Which diseases are caused by apicomplexans?

Refer to the diagram, which shows the role of vacuoles in ciliate digestion. The figure illustrates an experiment designed to determine whether Paramecium digests food in an acidic environment.This organism most likely _ and is _.

What would be a plausible outcome if cats developed a resistance to Toxoplasma?

Which of the following represents the synapomorphy of the stramenopiles?

Which statement does not apply to apicomplexans?

Which statement about microbial eukaryotes is false?

Dinoflagellates possess sacs beneath their plasma membranes and chloroplasts that contain pigments that give them a golden brown color.Dinoflagellates are therefore classified as

You are watching a Paramecium in fresh water and see a rounded structure within it enlarge and then suddenly contract as water is expelled.You have just witnessed the

When organic material is digested in a food vacuole, the pH in the vacuole

Refer to the figure. This phylogenetic tree shows one current hypothesis and estimated time line for the origin of the major groups of eukaryotes.Which clade of eukaryotes was the first to diverge from other eukaryotes?

Many dinoflagellates are ___ that have _.Most live in _____.

Refer to the diagram, which shows the role of vacuoles in ciliate digestion. Which of the following is a plausible hypothesis to explain why the vacuole color returns to red?