Question 1

In a recent study, researchers found that carbon dioxide was pumped to the ocean floor after adding a small amount of iron to the water. Which of the following organisms was likely responsible for this result?
A) dinoflagellates
B) forams
C) diatoms
D) slime molds

Accepted Answer

Diatoms are responsible for this result because they utilize iron as a nutrient to facilitate photosynthesis, which in turn increases their ability to absorb carbon dioxide from the atmosphere. When they die, they sink to the ocean floor, effectively sequestering the carbon.

Question 2

Slime molds and fungi were once included in the same taxonomic group due to some specific similarities in morphology and lifestyle. These two groups are now classified in different taxonomic groups. How would you describe these similarities now that the two groups are classified separately?
A) the similarities are homologies
B) the similarities are examples of convergent evolution
C) the similarities are variations of common ancestral traits
D) the similarities are adaptations for much different functions

Accepted Answer

The similarities between slime molds and fungi that led to their initial grouping are examples of convergent evolution, where unrelated species independently evolve similar traits as a result of having to adapt to similar environments or ecological niches.

Question 3

Which of the following results would be most likely if a layer of warm, light water caused by ocean surface warming blocks nutrient upwelling? A) reduced populations of fish because they avoid warm water B) increased populations of producers because they have access to more CO₂ C) reduced populations of producers because they have access to fewer nutrients D) increased populations of producers because fewer fish are produced, and they eat fewer producers

Accepted Answer

C) Reduced populations of producers because they have access to fewer nutrients. Nutrient upwelling is crucial for the productivity of marine ecosystems, providing the essential nutrients needed by phytoplankton, the base of the oceanic food web. If a layer of warm, light water blocks this upwelling, the supply of nutrients to surface waters would decrease, leading to reduced populations of producers that rely on these nutrients for photosynthesis.

Question 4

Similar to most amoebozoans, the forams and the radiolarians also have pseudopods, as do some of the white blood cells of animals. If one were to construct a taxon that included all organisms that have cells with pseudopods, what type of evolutionary pattern would the tree show?
A) polyphyletic
B) paraphyletic
C) monophyletic
D) it would include all eukaryotes

Accepted Answer

The tree would show a polyphyletic pattern because the trait of having pseudopods has arisen independently in different lineages (e.g., amoebozoans, forams, radiolarians, and some white blood cells in animals), rather than stemming from a common ancestor that had pseudopods and passed that trait down to all its descendants.

Question 5

A failure in which of the following processes can result in the formation of a supercell that is characteristic of plasmodial slime molds?
A) mitosis
B) cytokinesis
C) aerobic metabolism
D) endocytosis

Accepted Answer

A supercell in plasmodial slime molds results from repeated nuclear divisions (mitosis) without cytokinesis, leading to a large cell with many nuclei.

Question 6

Green algae and plants are placed in the same phylogenetic group. Which of the following statements presents evidence to support this classification?
A) similarities in mitochondrial structure and enzyme sequences
B) similarities in chloroplast structure and pigment composition
C) similarities in cell wall and membrane structure
D) DNA sequence similarities in genes for ribosome structure

Accepted Answer

Similarities in chloroplast structure and pigment composition are key pieces of evidence supporting the classification of green algae and plants in the same phylogenetic group, as both share chlorophyll a and b, which are critical for photosynthesis.

Question 7

Use the following information to answer the question.
Healthy individuals of Paramecium bursaria contain photosynthetic algal endosymbionts of the genus Chlorella. In addition, P. bursaria also ingests bacteria.
Which term most accurately describes the nutritional mode of healthy P. bursaria?
A) photoautotroph
B) photoheterotroph
C) chemoautotroph
D) mixotroph

Accepted Answer

P. bursaria is considered a mixotroph because it obtains nutrients through photosynthesis via its symbiotic relationship with Chlorella (making it partly autotrophic) and by ingesting bacteria (making it heterotrophic).

Question 8

You have discovered a photosynthetic protist that lives in fairly deep water (for example, 250 m deep).To which of the following groups should this organism be classified?
A) diatoms
B) green algae
C) red algae
D) cercozoan

Accepted Answer

Red algae are known for their ability to live in deeper water due to their pigments, which can absorb and utilize the blue light available at such depths, unlike many other photosynthetic organisms that rely on light available closer to the surface.

Question 9

Many chlorophytes are unicellular, but others are larger and more complex. What does this indicate regarding the evolutionary history of chlorophytes?
A) the chlorophyte group is not monophyletic
B) the chlorophyte group is monophyletic
C) the chlorophyte group is the protist group most closely related to plants
D) the chlorophyte group contained extensive genetic variability

Accepted Answer

The presence of both unicellular and more complex forms within chlorophytes suggests that there is extensive genetic variability within the group, allowing for a range of evolutionary adaptations and complexity.

Question 10

Amoebas are polyphyletic. Based on this fact, which of the following statements regarding their evolution is correct?
A) movement by pseudopodia evolved only once
B) scientists need to continue to investigate the origins and evolutionary history of protists
C) evolutionary history cannot be discovered
D) eukaryotes are also not monophyletic and need to be broken into many groups

Accepted Answer

Being polyphyletic means amoebas have evolved from multiple ancestral lines. This complexity necessitates ongoing research to fully understand their origins and evolutionary history.

Question 11

A biologist discovers an alga that is marine, multicellular, and lives at a depth reached only by blue light. Based on this information, to which of the following groups of algae would this organism be classified?
A) red algae
B) brown algae
C) green algae
D) golden algae

Accepted Answer

Red algae are known for their ability to live at greater depths than most other algae, thanks to their unique pigments that can absorb and utilize blue light, which penetrates deeper into the water.

Question 12

SAR is a highly diverse group of protists defined by DNA similarities determined through whole-genome analysis of various organisms in the group. Which of the following conclusions could be drawn from this information?
A) SAR is a paraphyletic group
B) SAR is a monophyletic group
C) SAR includes organisms that have different common ancestors
D) the common ancestor of the members of this group arose relatively recently in evolutionary history

Accepted Answer

The SAR group is considered a monophyletic group because it is defined by DNA similarities that indicate the members share a common ancestor, which is a characteristic of monophyletic groups.

Question 13

What do the multiple branching points at the root of the eukaryotic phylogenetic tree indicate about the evolution of eukaryotes?
A) that unikonts are derived from the SAR clade
B) that Archaeplastids were the first eukaryotes
C) that fungi are more closely related to plants than animals
D) that eukaryotes are all descended from a common ancestor

Accepted Answer

The multiple branching points at the root of the eukaryotic phylogenetic tree indicate that eukaryotes share a common ancestor. This reflects the complexity and diversity of eukaryotic life, suggesting that all eukaryotic organisms diverged from a single ancestral lineage.

Question 14

Which of the following statements correctly describes one difference between green algae and land plants?
A) green algae are often unicellular, while land plants are not
B) land plants have plastids and green algae do not
C) algae have alternation of generations but land plants do not
D) land plants have cell walls containing cellulose but green algae do not

Accepted Answer

Green algae can be unicellular or multicellular, whereas land plants are predominantly multicellular. This is a key difference, as land plants have evolved complex multicellular structures to adapt to terrestrial environments. Choices B, C, and D are incorrect because both green algae and land plants have plastids, both can have alternation of generations, and both have cell walls containing cellulose.

Question 15

Living diatoms contain brownish plastids. If global climate change continues to warm surface waters of Earth's oceans, which of the following is the most likely effect on the animals that build coral reefs?
A) The coral animals, which capture planktonic organisms, may be outcompeted by the diatoms.
B) The coral animals' endosymbiotic dinoflagellates may get "shaded out" by the diatoms.
C) The coral animals may die from overeating the plentiful diatoms with their cases of silica.
D) The diatoms' photosynthetic output may over-oxygenate the water.

Accepted Answer

Coral reefs rely on a symbiotic relationship with dinoflagellates, which are photosynthetic algae. If the surface waters warm, it can lead to conditions unfavorable for these dinoflagellates, such as being outcompeted for light and nutrients by other organisms like diatoms. This can disrupt the symbiotic relationship, leading to coral bleaching and potentially the death of coral reefs.

Question 16

Researchers have shown that "income levels in countries hard hit by malaria are 33% lower than in countries with similar income that are free of the disease." Which of the following statements is correct regarding this observation?
A) This observation suggests that symptoms from malaria cause patients to lose pay because they miss work.
B) This observation is an example of a correlation and therefore causality cannot be inferred as confidently as if we have results from a manipulated experiment.
C) In order to understand the cause of this observation, scientists should eradicate malaria in ten countries but not in ten other comparable countries in order to experimentally test whether malaria caused the low income levels.
D) The observation demonstrates that correlations provide excellent indications of causality.

Accepted Answer

This observation is a correlation between malaria prevalence and lower income levels. Correlation does not imply causation, meaning we cannot confidently conclude that malaria directly causes lower income levels without further experimental evidence.

Question 17

Which of the following types of protists causes the potentially fatal disease dysentery?
A) Entamoeba histolytica
B) Amoeba proteus
C) plasmodial slime molds
D) Dictyostelium discoideum

Accepted Answer

Entamoeba histolytica is the protist responsible for causing dysentery, a severe form of diarrhea that may include blood. This organism infects the colon through contaminated food or water.

Question 18

Which of the following organisms is a producer?
A) kinetoplastids
B) apicomplexans
C) diatoms
D) ciliates

Accepted Answer

Diatoms are producers because they are photosynthetic algae, capable of converting light energy into chemical energy through the process of photosynthesis, thus producing organic compounds from inorganic substances.

Question 19

You have discovered that some members of an aquatic species of motile, photosynthetic protists have evolved to become parasitic to fish. They gain the ability to live in the fish gut, absorbing nutrients as the fish digests food. Over time, which of the following phenotypic changes would you expect to observe in this population of protists?
A) loss of motility
B) loss of chloroplasts
C) gain of a rigid cell wall
D) gain of meiosis

Accepted Answer

The answer of You have discovered that some members of...

Question 20

Which of the following groups is matched with a correct anatomical feature?
A) foraminifera-silicon-rich tests
B) dinoflagellata-holdfast
C) diatoms-tests made of cellulose
D) brown algae-blade

Accepted Answer

Brown algae are characterized by their unique anatomical features, including a blade, which is a leaf-like structure that assists in photosynthesis. The other options are incorrect matches to the listed groups.

Quiz 28: The Origin and Evolution of Eukaryotes

In a recent study, researchers found that carbon dioxide was pumped to the ocean floor after adding a small amount of iron to the water. Which of the following organisms was likely responsible for this result?

Slime molds and fungi were once included in the same taxonomic group due to some specific similarities in morphology and lifestyle. These two groups are now classified in different taxonomic groups. How would you describe these similarities now that the two groups are classified separately?

Which of the following results would be most likely if a layer of warm, light water caused by ocean surface warming blocks nutrient upwelling?

Similar to most amoebozoans, the forams and the radiolarians also have pseudopods, as do some of the white blood cells of animals. If one were to construct a taxon that included all organisms that have cells with pseudopods, what type of evolutionary pattern would the tree show?

A failure in which of the following processes can result in the formation of a supercell that is characteristic of plasmodial slime molds?

Green algae and plants are placed in the same phylogenetic group. Which of the following statements presents evidence to support this classification?

Use the following information to answer the question. Healthy individuals of Paramecium bursaria contain photosynthetic algal endosymbionts of the genus Chlorella. In addition, P. bursaria also ingests bacteria. Which term most accurately describes the nutritional mode of healthy P. bursaria?

You have discovered a photosynthetic protist that lives in fairly deep water (for example, 250 m deep) .To which of the following groups should this organism be classified?

Many chlorophytes are unicellular, but others are larger and more complex. What does this indicate regarding the evolutionary history of chlorophytes?

Amoebas are polyphyletic. Based on this fact, which of the following statements regarding their evolution is correct?

A biologist discovers an alga that is marine, multicellular, and lives at a depth reached only by blue light. Based on this information, to which of the following groups of algae would this organism be classified?

SAR is a highly diverse group of protists defined by DNA similarities determined through whole-genome analysis of various organisms in the group. Which of the following conclusions could be drawn from this information?

What do the multiple branching points at the root of the eukaryotic phylogenetic tree indicate about the evolution of eukaryotes?

Which of the following statements correctly describes one difference between green algae and land plants?

Living diatoms contain brownish plastids. If global climate change continues to warm surface waters of Earth's oceans, which of the following is the most likely effect on the animals that build coral reefs?

Researchers have shown that "income levels in countries hard hit by malaria are 33% lower than in countries with similar income that are free of the disease." Which of the following statements is correct regarding this observation?

Which of the following types of protists causes the potentially fatal disease dysentery?

Which of the following organisms is a producer?

Which of the following groups is matched with a correct anatomical feature?