Homework 3

Which of these are the two major sources of nitrate pollution in rivers?

animal wastes and fertilizers

What has metagenomic analysis allowed researchers to do for the first time?

study organisms that cannot be cultured (grown in the lab)

If two species of bacteria use glucose as an electron donor, but species A uses oxygen as the final electron acceptor and species B uses nitrate, then how much glucose would species B need to use to generate the same amount of ATP as species A? See Section 26.3 (Page) .

~60% more glucose

What other types of evidence or features might be used to ascertain whether the tree of life is best represented according to the three-domain or the eocyte hypothesis?

- DNA sequence data -cell biology -the fossil record

The Bacteria and Archaea include microscopic prokaryotes that lack membrane-bound nuclei. What criteria have lead to the classification of these two groups as separate domains?

- different types of DNA polymerases- plasma membranes and cell walls are composed of different molecules- different types of RNA polymerases- different types of ribosomes

Which of the following conditions can be varied in an enrichment culture to isolate bacteria that prefer a specific set of conditions? See Section 26.2 (Page) .

-pH -food source -temperature

The researchers who observed that magnetite was produced by bacterial cultures from the deep subsurface carried out a follow-up experiment. These biologists treated some of the cultures with a drug that poisons the enzymes involved in electron transport chains. In cultures where the drug was present, no more magnetite was produced. 1) Does this result support or undermine their hypothesis that the bacteria in the cultures perform cellular respiration? 2) Explain your reasoning.

1) support 2) The drug poisons the enzymes of the electron transport chain and prevents electron transfer to Fe3+, which is required to drive magnetite synthesis.

1)What advantage do organisms that reproduce sexually have over organisms that reproduce asexually? 2)Which term describes the fusion of two gametes to form a diploid zygote? 3)Which term describes the multicellular haploid form of a protist that shows alternation of generations? 4)Which structure mediates the attachment of spores to a surface on which to grow? 5)Which of the following statements about Ulva's haploid stage is true? 6)How does the haploid form of Ulva "switch" to its diploid form? 7)True or false? Organisms that exhibit alternation of generations reproduce sexually in the diploid stage.

1)Their offspring may be more adaptable to changes in the environment. 2)Fertilization 3)Gametophyte 4)Holdfast 5)Haploid cells are produced by meiosis of diploid cells. 6)Gametophytes produce cells that undergo mitosis to produce gametes that fuse to form a zygote. 7)False

1)The cells of _____ and _____ have modified mitochondria. 2)The members of _____ are characterized by cells with small membrane-bounded cavities under their cell membranes. 3)Golden algae, brown algae, red algae, chlorophytes, and charophyceans are some examples of protists that are _____. 4)Which of these groups consist of parasitic flagellated cells, such as Trypanosoma, the organism that causes sleeping sickness? 5)Which three groups contain large algae known as seaweeds? 6)Stramenopiles include all of the following groups EXCEPT ______. 7)Which of these groups is characterized by glasslike walls containing silica? 8)Plasmodium, the parasitic organism that causes malaria, is a _____. 9)A paramecium is a(n) _____. 10)The largest seaweeds are _____. 11)All of the organisms classified as _____ move and feed using cilia. 12)Which group is characterized by cells with fine hairlike projections on their flagella? 13)Which of these algal groups possess a photosynthetic pigment that allows them to live in deep water? 14)Which of these groups includes both aquatic decomposers and the parasites responsible for late potato blight? 15)Which algal group has chloroplasts much like those of green plants in structure and pigment makeup?

1)diplomonads ...parabasalids 2)Alveolata 3)photosynthetic 4)kinetoplastids 5)brown algae, red algae, and green algae 6)cellular slime molds 7)diatoms 8)apicomplexan 9)ciliate 10)brown algae 11)ciliates 12)Stramenopila 13)red algae 14)oomycetes 15)chlorophytes

Approximately how many times larger is the diameter of Thiomargarita than Mycoplasma? See Section 26.3 (Page)

500 times as large

What is the diameter of the smallest known eukaryotes? See Section 27.3 (Page)

< 0.2 µm

Which of the following statements about phylogenetic trees is true?

A paraphyletic group consists of a common ancestor and some of its descendants.

What is a potential ill effect of adding iron to ocean waters? See Section 27.1 (Page) .

An algal bloom that causes a massive loss of oxygen, creating a dead zone

Biologists often use the term energy source as a synonym for "electron donor." Why?

An electron donor provides the potential energy required to produce ATP.

Where on the phylogenetic tree should the origin of chloroplasts appear? See Section 27.4 (Page) .

At the base of Plantae

Where on the phylogenetic tree should the origin of alveoli structure appear? See Section 27.4 (Page) .

At the base of alveolates

Where on the phylogenetic tree should the origin of the supercell appear? See Section 27.4 (Page)

At the base of plasmodial slime molds

Where on the phylogenetic tree should the origin of the nuclear envelope appear? See Chapter 27 (Page) .

At the very base of the eukaryotes

Why are Archaea considered a monophyletic group according to the three-domain hypothesis?

Because this group includes an ancestral population and all of its descendants.

Robert Koch is best known for which of the following contributions? See Section 26.1 (Page) .

Establishing a link between microbes and disease

Which of the following is an observed electron donor and its associated electron acceptor for the archaea that produce methane (swamp gas)? See Section 26.2 (Page) .

H2 and CO2

Aerobic respiration is more efficient than anaerobic respiration because of what property of oxygen? See Section 26.3 (Page) .

It is highly electronegative.

When using Koch's postulates, which of the following is an essential requirement for the suspected pathogen?

It is present in all organisms with the disease.

The text claims that the evolution of an oxygen atmosphere paved the way for increasingly efficient cellular respiration and higher growth rates in organisms. Explain.

Large amounts of potential energy are released when oxygen is the electron acceptor, because oxygen is so electronegative. The large amount of energy is required for large body size and high growth rates.

What method would you use to best identify the diversity of bacterial and archaeal species in the soil present on your campus? See Section 26.2 (Page) .

Metagenomics

Which of the following types of metabolism are found in archaea or bacteria but not found in eukaryotes? See Section 26.3 (Page) .

Methanogenesis

Which evidence is consistent with the endosymbiotic hypothesis for the origin of the mitochondrion? See Section 27.3 (Page) .

Mitochondria have their own ribosomes and manufacture their own proteins.

Are the gametes of brown algae formed by meiosis or by mitosis? See Section 27.3 (Page) .

Mitosis of gametophyte cells

Early ideas on the classification of life recognized all organisms as belonging to one of two fundamental lineages−−prokaryotes or eukaryotes. Is this view compatible with either of the hypotheses illustrated above? Explain.

No, because each hypothesis presents prokaryotes as two separate groups.

An experimenter prepared an enrichment culture using a soil sample obtained from below the earth's surface. The culture was abundant in H2 and Fe3+ and was incubated above 45°C to mimic the conditions a mile below the earth's surface. After a suitable period of time, no bacteria were observed to be growing. Is this strong evidence that bacteria cannot grow a mile below earth's surface? See Section 26.2 (Page) .

No. Perhaps other conditions were necessary to grow bacteria from this particular soil sample

Why do species that release H2S as a by-product often live side by side with species that use H2S as an electron donor? See Section 26.3 (Page) .

One species provides the necessary chemical for the other to survive.

What distinguishes bacteria from archaea? See Section 26.1 (Page)

Only bacteria have peptidoglycan in their cell walls.

What is the electron acceptor for humans in the electron transport chain? See Section 26.3 (Page) .

Oxygen

Why can dinoflagellate blooms be harmful to humans? See Section 27.1 (Page) .

People can get paralytic shellfish poisoning during dinoflagellate blooms.

What is lateral gene transfer?

Physical transfer of a gene from a species in one lineage to a species in another lineage.

What characteristics were used to classify organisms before Woese's tree of life analysis?

Presence of a membrane-bound nucleus

Which group was not described in Woese's tree of life analysis?

Prokarya

Which molecule did Carl Woese study to produce his tree of life?

Ribosomal RNA

Researchers have proposed that slime molds could be used to help to plan the paths of future roadways and railways. Justify this statement.

Slime molds find the shortest route possible from one food item to another, therefore conserving energy. This decision-making process could be used to design roads or rail lines that connect major cities.

Members of which bacterial phylum share a unique morphology? See Section 26.4 (Page) .

Spirochaetes

Why does iron fertilization of open oceans increase phytoplankton densities? See Section 27.2 (Page)

The growth of phytoplankton is often limited by iron availability in the open oceans.

Consider the endosymbiosis theory for the origin of the mitochondrion. How did each endosymbiotic partner benefit from the relationship?

The host cell provided a protected environment and carbon compounds for the endosymbiont; the endosymbiont provided increased ATP from the carbon compounds.

What evidence supports the hypothesis that the nuclear envelope of eukaryotes arose from infolding of the plasma membrane? See Section 27.3 (Page) .

The nuclear membrane and endoplasmic reticulum (ER) of modern eukaryotes are continuous.

If prokaryotes did not exist, what would change in the nitrogen cycle? See Section 26.3 (Page) .

The rate of movement of nitrogen atoms through ecosystems would be much slower.

Which of the following best describes movement in Physarum?

The slime mold moves by amoeboid motion.

Actin and tubulin are proteins that play important roles in cell division in eukaryotes. Genes that code for these proteins were recently found in eocytes (and a few closely related groups) but not in other archaea or bacteria. Are these findings more consistent with the three-domain or eocyte hypothesis?

These findings are more consistent with the eocyte hypothesis. The presence of these genes in eocytes and eukaryotes is consistent with these two groups being derived from a common ancestor

Which is true of archaea? See Section 26.4 (Page) .

They have unique ether-linked lipids in their plasma membranes.

True or false? Data showing that the Bacteria were the first lineage to diverge from the common ancestor of all living organisms suggest that the Archaea and Eukarya are more closely related to each other than they are to the Bacteria.

True

According to the endosymbiosis theory, how many membranes should a mitochondrion have? See Section 27.3 (Page) .

Two

What is unique about sex in ciliates? See Section 27.4 (Page)

Two ciliates reproduce sexually by conjugation, changing their genetic makeup but not producing any additional cells

Select the correct statement about the Unikonta and Bikonta. See Section 27.3 (Page) .

Unikont and bikont lineages split soon after the origin of eukaryotes

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

a cyanobacterium

Which feature is unique to diplomonads? See Section 27.4 (Page)

a double nucleus

Aquatic nitrate pollution can result in _____.

an algal bloom that, when the algae die and are decomposed by bacteria, leads to hypoxia and the death of fish

Organisms that synthesize their own C-C molecules from single-carbon starting materials are named _____, while those that absorb preformed C-C compounds produced by other organisms are _____. See Section 26.3 (Page) .

autotrophs; heterotrophs

Which of the following groups of organisms is among the most abundant on Earth? See Section 26.1 (Page) .

bacteria

Other hypotheses for the tree of life present the Archaea as the ancestors to all other organisms. Make a sketch of a phylogenetic tree that presents Bacteria and Eukarya as more closely related to each other than to Archaea, and has Archaea as a sister group to Bacteria and Eukarya.

bacteria and eukarya are closer than archaea on a phylogenetic tree

What feature was not present in the first eukaryotes? See Section 27.2 (Page) .

cell wall

The important primary producers in marine ecosystems with cellulose cell walls are _____.

dinoflagellates

Chloroplasts found in plants arose via _____. See Section 27.3 (Page) .

endosymbiosis of cyanobacteria

What are organisms called that use building-block compounds from other organisms?

heterotrophs

What do some photosynthetic bacteria use as a source of electrons instead of water?

hydrogen sulfide (H2S)

What does amoeboid motion result from?

interactions among actin, myosin, and ATP

What synapomorphy defines the Eukarya? See Section 27.1 (Page) .

nuclear envelope

Cyanobacteria are thought to be the first organisms to evolve ____. See Section 26.3 (Page) .

oxygenic photosynthesis

Unlike plant cell walls that contain cellulose, bacterial cell walls are composed of _____.

peptidoglycan

Molecular phylogenies were first used to separate bacterial and archaeal lineages based upon the sequence data from which of the following molecules? See Section 26.2 (Page) .

ribosomal small subunit RNA

A gametophyte is formed directly from a _____. See Section 27.3 (Page)

spore

The Gram stain, commonly used to classify a bacterial isolate into one of two groups, is based upon the characteristics of which of the following structures? See Section 26.3 (Page)

the cell wall

In a rapidly changing environment, protists tend to reproduce _____. See Section 27.3 (Page) .

via sexual reproduction