exam 2 biology practice exam part 1

In a bacterium that possesses antibiotic resistance and the potential to persist through very adverse conditions, such as freezing, drying, or high temperatures, DNA should be located within, or be part of, which structures? 1. nucleoid region 2. endospore 3. fimbriae 4. plasmids

1,2, and 4

The termite gut protist Mixotricha paradoxa has at least two kinds of bacteria attached to its outer surface. One kind is a spirochete that propels its host through the termite gut. A second type of bacteria synthesizes adenosine triphosphate (ATP), some of which is used by the spirochetes. The locomotion provided by the spirochetes introduces the ATP-producing bacteria to new food sources. Which term(s) is (are) applicable to the relationship between the two kinds of bacteria? 1. mutualism 2. parasitism 3. symbiosis 4. metabolic cooperation

1,3,4

Plasmogamy can directly result in which of the following? 1. cells with a single haploid nucleus 2. heterokaryotic cells 3. dikaryotic cells 4. cells with two diploid nuclei

2 or 3

The thermoacidophile Sulfolobus acidocaldarius lacks peptidoglycan, but still possesses a cell wall. What is likely to be true of this species? 1. It is a bacterium. 2. It is an archaean. 3. The optimal pH of its enzymes will lie above pH 7. 4. The optimal pH of its enzymes will lie below pH 7. 5. It could inhabit certain hydrothermal springs. 6. It could inhabit alkaline hot springs.

2,4,5

Use the graph to estimate the divergence time for a mammal with a total of 30 mutations in the seven proteins.

50 million years

Which of the following is true of secondary endosymbiosis?

An organism containing an endosymbiont is engulfed by another organism and becomes an endosymbiont.

While examining a rock surface, you have discovered an interesting new organism. Which of the following criteria will allow you to classify the organism as belonging to Bacteria but not Archaea or Eukarya?

Cell walls are made primarily of peptidoglycan.

Select the correct statement about bacteria.

Certain bacteria live within rocks kilometers below the Earth's surface.

Why do researchers use rRNA in investigations of relationships between taxa that diverged hundreds of millions of years ago?

DNA coding for rRNA changes relatively slowly

Which statement about endotoxins is true?

Endotoxins are released only when bacteria die and their cell walls break down.

Sexual reproduction in eukaryotes increases genetic variation. In prokaryotes, transformation, transduction, and conjugation are mechanisms that increase genetic variation. A fundamental difference between the generations of genetic variation in the two domains is:

Eukaryotic genetic variation occurs with vertical gene transfer while prokaryotic genetic variation occurs with horizontal gene transfer.

Which of the following is a difference between plants and fungi? Hints

Fungi are heterotrophic, and plants are autotrophic.

Why are mycorrhizal fungi superior to plants at acquiring mineral nutrition from the soil?

Fungi secrete extracellular enzymes that can break down large molecules.

Which statement about the domain Archaea is true?

Genetic prospecting has recently revealed the existence of many previously unknown archaean species.

You have found a new prokaryote. What line of evidence would support your hypothesis that the organism is a cyanobacterium?

It is able to form colonies and produce oxygen

Select the correct statement about photosynthesis by primary producers.

Photosynthetic protists and prokaryotes carry out the majority of the photosynthesis in aquatic communities.

Which eukaryotic kingdom includes members that are the result of endosymbioses that included an ancient aerobic bacterium and an ancient cyanobacterium?

Plantae

In prokaryotes new mutations accumulate quickly in populations, while in eukaryotes new mutations accumulate much more slowly. The primary reasons for this are

Prokaryotes have short generation times and large population sizes.

According to the endosymbiotic theory, why was it adaptive for the larger (host) cell to keep the engulfed cell alive, rather than digesting it as food?

The engulfed cell provided the host cell with adenosine triphosphate (ATP).

Which of the following observations about flagella is true and is consistent with the scientific conclusion that the flagella from protists and bacteria evolved independently?

The protein structure and the mechanism of movement in protist flagella are different from those of bacteria flagella.

If all prokaryotes on Earth suddenly vanished, which of the following would be the most likely and most direct result?

The recycling of nutrients would be greatly reduced, at least initially.

Identify the thylakoid membrane of the cyanobacterium shown here.

The thylakoid membrane of the cyanobacterium is an infolded plasma membrane.

When a virus infects a bacterial cell, often new viruses are assembled and released when the host bacterial cell is lysed. If these new viruses go on to infect new bacterial cells the host cells may not be lysed. What is the most plausible explanation for this?

The virus has entered the genome of the bacterial cell and is in the lysogenic stage.

Which statement is true about obligate anaerobes?

They are poisoned by o2

What is the function of fimbriae?

They are used to attach the cell to its substrate or to other prokaryotes.

Basidiomycetes are the only fungal group capable of synthesizing lignin peroxidase. What advantage does this group of fungi have over other fungi because of this capability?

This fungal group can break down the tough lignin, which cannot be harnessed for energy, to get to the more useful cellulose.

Fungi obtain nutrients through _____.

absorption

Biologists suspect that endosymbiosis gave rise to mitochondria before plastids partly because

all eukaryotes have mitochondria (or their remnants), whereas many eukaryotes do not have plastids.

The adaptive advantage associated with the filamentous nature of fungal mycelia is primarily related to _____.

an extensive surface area well suited for invasive growth and absorptive nutrition

Green algae differ from land plants in that many green algae _____.

are unicellular

Which of the following is LEAST associated with the others?

binary fission

The multicellular condition of animals and fungi seems to have arisen _____.

by convergent evolution

Use the following information to answer the question(s) below. For several decades now, amphibian species worldwide have been in decline. A significant proportion of the decline seems to be due to the spread of the chytrid fungus, Batrachochytrium dendrobatidis (Bd). Chytrid sporangia reside within the epidermal cells of infected animals, animals that consequently show areas of sloughed skin. They can also be lethargic, which is expressed through failure to hide and failure to flee. The infection cycle typically takes four to five days, at the end of which zoospores are released from sporangia into the environment. In some amphibian species, mortality rates approach 100%; other species seem able to survive the infection. Apart from direct amphibian-to-amphibian contact, what is the most likely means by which the zoospores spread from one free-living amphibian to another?

by flagella

Consider the following data: (a) Most ancient eukaryotes are unicellular. (b) All eukaryotes alive today have a nucleus and cytoskeleton. (c) Most ancient eukaryotes lack a cell wall. Which of the following conclusions could reasonably follow the data presented? The first eukaryote may have been _____.

capable of phagocytosis

Bacteria that live around deep-sea, hot-water vents obtain energy by oxidizing inorganic hydrogen sulfide belched out by the vents. They use this energy to build organic molecules from carbon obtained from the carbon dioxide in seawater. These bacteria are _____.

chemoautotrophs

Plantlike photosynthesis that releases O2 occurs in

cyanobacteria

The chloroplasts of land plants are thought to have been derived according to which evolutionary sequence?

cyanobacteria → green algae → land plants

A fungal spore germinates, giving rise to a mycelium that grows outward into the soil surrounding the site where the spore originally landed. Which of the following accounts for the fungal movement, as described here?

cytoplasmic streaming in hyphae

Bacteria perform each of the following ecological roles. Which role typically does NOT involve symbiosis?

decomposer

Bacteria perform the following ecological roles. Which role typically does not involve symbiosis?

decomposer

Which of the following is a producer?

diatom

All protists are _____.

eukaryotic

When a mycelium infiltrates an unexploited source of dead organic matter, what are most likely to appear within the food source soon thereafter?

fungal enzymes

The diploid phase of the life cycle is shortest in which of the following?

fungus

what process actually increases the number of genes in an organism genome?

gene duplication

he prokaryotic organisms most likely to be found living in salt ponds are the _____.

halophiles

A particular species of protist has obtained a chloroplast via secondary endosymbiosis. You know this because the chloroplasts _____.

have three or four membranes

An important example of interaction between fungi and certain other organisms is mycorrhizae, in which the fungal partners _____.

help plants take up nutrients and water

A crucial photosynthetic gene of the cyanobacterium that gave rise to the chromatophore is called psaE. This gene is present in the nuclear genome of the cercozoan, but is not in the genome of the chromatophore. This is evidence of _____.

horizontal gene transfer from bacterium to eukaryotes

The body of most fungi consists of threadlike _____, which form a network called a _____.

hyphae ... mycelium

Chloramphenicol is an antibiotic that targets prokaryotic (70S) ribosomes, but not eukaryotic (80S) ribosomes. Which of these questions stems from this observation, plus an understanding of eukaryotic origins?

if chloramphenicol inhibits prokaryotic ribosomes, should it not also inhibit mitochondrial ribosomes?

What sexual processes in fungi generate genetic variation?

karyogamy and meiosis

Genetic variation in bacterial populations cannot result from

meiosis

The lakes of northern Minnesota are home to many similar species of damselflies of the genus Enallagma. These species have apparently undergone speciation from ancestral stock since the last glacial retreat about ten thousand years ago. Sequencing which of the following would probably be most useful in sorting out evolutionary relationships among these closely related species?

mitochondrial DNA

Which of the following would, if it had acted upon a gene, prevent this gene from acting as a reliable molecular clock?

natural selection

Molecular clocks are based on the idea that _____.

on average neutral mutations arise at a constant rate

Encouraging the growth (via nutrient fertilization) of photosynthetic protists in marine environments may help reduce global warming because _____

photosynthetic protists fix atmospheric carbon dioxide, decreasing atmospheric carbon dioxide level

_____ are eukaryotic autotrophs that float near the surface of water and are the basis of the food chain.

phytoplankton

Genes for the resistance to antibiotics are usually located _____.

plasmids

Based on cladistics, which eukaryotic kingdom is polyphyletic and, therefore, unacceptable?

protista

What kind of evidence has recently made it necessary to assign the prokaryotes to either of two different domains, rather than assigning all prokaryotes to the same kingdom?

rRNA genes

The most important feature that permits a gene to act as a molecular clock is _____

reliable average rate of mutation

In most fungi, karyogamy does not immediately follow plasmogamy, which consequently _____.

results in heterokaryotic or dikaryotic cells

Plastids that are surrounded by more than two membranes are evidence of

secondary endosymbiosis

Which statement represents the best explanation for the observation that the nuclear DNA of wolves and domestic dogs has a very high degree of sequence homology? Dogs and wolves _____.

share a very recent common ancestor

An ecological relationship between organisms of different species that are in direct contact can best be described as _____.

symbiotic

How are archaeans most similar to bacteria?

the shape of their chromosomes and plasmids

Biologists sometimes divide living organisms into two groups: autotrophs and heterotrophs. These two groups differ in _____.

their mode of nutrition

How does the large amount of genetic variation observed in prokaryotes arise?

they have extremely short generation times and large populations. They can exchange DNA with many types of prokaryotes by way of horizontal gene transfer.

What is the goal of bioremediation?

to clean up areas polluted with toxic compounds by using bacteria

Which of the following processes contributes to genetic recombination in prokaryotes?

transduction

Jams, jellies, preserves, honey, and other foods with high sugar content hardly ever become contaminated by bacteria, even when the food containers are left open at room temperature. This is because bacteria that encounter such an environment ____.

undergo death as a result of water loss from the cell