Biology Midterm

Which of the following is a defining characteristic that all protocells had in common?

A surrounding membrane or membrane-like structure

To understand the chemical basis of inheritance, we must understand the molecular structure of DNA. This is an example of the application of which concept to study of biology?

Reductionism

The role that humans play in artificial selection is to -

choose which organisms reproduce

You are given an unknown organism to identify. It is unicellular and heterotrophic. It is motile, using many short extensions of the cytoplasm, each featuring the 9 + 2 filament pattern. It has well-developed organelles and two nuclei, one large and one small. This organism is most likely to be a -

cilate

which process in pramecium results in genetic recombination but no increase in population size?

conjugation

the evolution of similar insulating skin coverings such as fur, hair, and feathers in mammals and birds is a result of -

convergent evolution

The first genetic material on Earth was probably -

self-replicating RNA molecules

In comparison to eukaryotes, prokaryotes are --

smaller

Many species of snakes lay eggs. However, in the forest of northern Minnesota, where growing seasons are short, only live-bearing snake species are present. This trend towards species that have live birth in a particular environment is an example of -

species selection

A hypothetical bacterium swims among human intestinal contents until it finds a suitable location on the intestinal lining. It adheres to the intestinal lining using a feature that also protects it from phagocytes, bacteriophages, and dehydration. Fecal matter from a human in whose intestine this bacterium lives can spread the bacterium, even after being mixed with water and boiled. The bacterium is not susceptible to the penicillin family of antibiotics. It contains no plasmids and relatively little peptidoglycan. This bacterium's ability to survive in a human who is taking penicillin pills may be due to the presence of - 1. penicillin resistance genes 2. a secretory system that removes penicillin from the cell 3. a gram-positive cell wall 4. a gram-negative cell wall 5. an endospore

2, 4, or 5

Nitrogenase, the enzyme that catalyzes nitrogen fixation, is inhibited whenever free O₂ reaches a critical concentration. Consequently, nitrogen fixation cannot occur in cells wherein photosynthesis produces free O₂. Consider the colonial aquatic cyanobacterium, Anabaena, whose heterocytes are described as having "...a thickened cell wall that restricts entry of O₂ produced by neighboring cells. Intracellular connections allow heterocysts to transport fixed nitrogen to neighboring cells in exchange for carbohydrates." Given that the enzymes that catalyze nitrogen fixation are inhibited by oxygen, what are two "strategies" that nitrogen-fixing prokaryotes might use to protect these enzymes from oxygen? 1. couple them with photosystem II (the photosystem that splits water molecules) 2. package them in membranes that are impermeable to all gases 3. be obligate anaerobes 4. be strict aerobes 5. package these enzymes in specialized cells or compartments that inhibit oxygen entry

3 and 5

What is thought to be the correct sequence of these events, from earliest to most recent, in the evolution of life on Earth? 1. Origin of mitochondria 2. Origin of multicellular eukaryotes 3. Origin of chloroplasts 4. Origin of cyanobacteria 5. origin of fungal0plant symbioses

4, 1, 3, 2, 5

Adherence to the intestinal lining by the bacterium is due to its possession of -

A capsule

Darwin's finches, collected from the Galapagos Islands, illustrate which of the following?

Adaptive radiation

A hypothetical bacterium swims among human intestinal contents until it finds a suitable location on the intestinal lining. It adheres to the intestinal lining using a feature that also protects it from phagocytes, bacteriophages, and dehydration. Fecal matter from a human in whose intestine this bacterium lives can spread the bacterium, even after being mixed with water and boiled. The bacterium is not susceptible to the penicillin family of antibiotics. It contains no plasmids and relatively little peptidoglycan. This bacterium derives nutrition by digesting human intestinal contents. Thus, this bacterium is an -

Anaerobic chemoheterotroph

For many years scientists believed that almost all animal lineage burst into being during the Cambrian era (just after the end of the Precambrian super eon). However, there have been many recent findings of animal-like fossils and "trace fossils" (fossils of an animal-like organisms movement) from the late Precambrian. Which of the following best explains why it took so long to realize there was animal-like life in the Precambrian?

Animals from the late Precambrian had soft bodies

Which of the following types of cells utilize DNA as their genetic material but do not have their DNA encased within a nuclear envelope?

Archaean

You are the lucky student of a wacky professor who develops a time machine. He asks if you will test it with him. You get in and there is an immediate glitch - the date reachout fails so that when you land you are not sure what era you are in. As your time machine lands, you see an unusual landscape before you. As you open the door you realize you cannot breathe. You quickly shut the door, realizing you are in the -

Archaean eon

The cow Bos Primigenius (which is bred for meat and milk) has a smaller brain and larger eyes than closely related wild species of ungulates. These traits most likely arose by -

Artificial selection, because changes in these traits co-occurred with human selection for high milk output and high muscle content

Prokaryotes are classified as belonging to two different domains. What are the domains?

Bacteria and Archaea

A gelatinous seaweed that grows in shallow, cold water and undergoes heteromorphic alternation of generations is most probably what type of alga?

Brown

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

An early consequence of the release of oxygen gas by plant and bacterial photosynthesis was to -

Cause iron in ocean water and terrestrial rocks to rust (oxidize)

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

During a study session about evolution, one of your fellow students remarks, "The giraffe stretched its neck while reaching for higher leaves; its offspring inherited longer necks as a result." Which statement is most likely to be helpful in correcting this student's misconception?

Characteristics acquired during an organism's life are generally not passed on through genes

Cells are --

Characteristics of prokaryotic and eukaryotic organisms

Which of the following have chloroplasts (or structures since evolved from chloroplasts) thought to be derived from ancestral green algae?

Chlorarachniophytes

Which of the following was derived from an ancestral cyanobacterium?

Chloroplast

which of these conditions are always true of populations evolving due to natural selection? Condition 1: the population must vary in traits that are heritable Condition 2: Some heritable traits must increase reproductive success Condition 3: Individuals pass on most traits that they acquire during their lifetime.

Condition 1 and 2

A researcher discovered a species of moth that lays its eggs on oak trees. Eggs are laid at two distinct times of the year: early in spring when the oak trees are flowering in midsummer when flowering is past. Caterpillars from eggs that hatch in spring feed on oak flowers and look like oak flowers. But caterpillars that hatch in summer feed on oak leaves and look like oak twigs. How do the same population of moths produce such different-looking caterpillars on the same trees? To answer this question, the biologist caught many female moths from the same population and collected their eggs. He put at least one egg from each female into eight identical cups. The eggs hatched, and at least two larvae from each female were maintained in one of the four temperature and light conditions listed below. Temperature Day Length Springlike Summerlike Summerlike Springlike Summerlike Summerlike In each of the four environments, one of the caterpillars was fed oak flowers, the other oak leaves. Thus, there were a total of eight treatment groups. (4 environments x 2 diets) Which of the following is not a plausible hypothesis to explain the differences in caterpillar appearance observed in this population?

Differences in air pressure, due to differences in elevation, trigger the development of different types of caterpillars.

Darwin and Wallace's theory of evolution by natural selection was revolutionary because it -

Dismissed the idea that specifics are constant and emphasized the importance of variation and change in populations

After the drought of 1977, researchers on the island of Daphne Major hypothesized that medium ground finches that had large, deep beaks, survived better than those with smaller beaks because they could more easily crack and eat the tough Tribulus cistoides fruits. If this hypothesis is correct, what would you expect to observe if a population of these medium ground finches colonized a nearby island where Tribulus cistoides is the most abundant food for the next 1000 years? Assume that (1) even the survivors of the 1977 drought sometimes had difficulty cracking the tough T. cistoides fruits and would eat other seeds when offered a choice; and (2) food availability is the primary limit on finch fitness on this new island.

Evolution of yet larger, deeper beaks over time

Which statement about the domain archaea is true?

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

Which of the following must exist in a population before natural selection can act upon that population?

Genetic variation among individuals

Use of synthetic fertilizers often leads to the contamination of groundwater with nitrates. Nitrate pollution is also a suspected cause of anoxic "dead zones" in the ocean. Which of the following might help reduce nitrate pollution?

Growing improved crop plants that have nitrogen-fixing enzymes

How were conditions on the early Earth of more than three billion years ago different from those on today's Earth? Unlike Earth today, early Earth -

Had an atmosphere rich in gases released from volcanic eruptions

A large seaweed that floats freely on the surface of deep bodies of water would be expected to lack which of the following?

Holdfasts

Which process could have allowed the nucleomorphs of chlorarachniophytes to be reduced, without the net loss of any genetic information?

Horizontal gene transfer

Several scientific laboratories across the globe are involved in research concerning the origin of life on Earth. Which of these questions is currently the most problematic and would have the greatest impact on our understanding if we were able to answer it?

How did RNA sequences come to carry the code for amino acid sequences

Diatoms are mostly asexual members o the phytoplankton. Diatoms lack any organelles that might have the 9 +2 pattern. They obtain their nutrition from functional chloroplasts, and each diatom is encased within two porous, glasslike valves. Which question would be most important for one interested in the day-to-day survival of individual diatoms?

How do diatoms with their glasslike valves keep from sinking into poorly lit waters?

Which of the following is the correct sequence of events in the origin of life? I. formation of protobionts II. synthesis of organic monomers III. synthesis of organic polymer IV. Formation of DNA-based genetic systems

II, III, IV, I

If Darwin had been aware of genes and their typical mode of transmission to subsequent generations, with which statement would he most likely have been in agreement?

If natural selection can change gene frequency in a population over generations, given enough time and genetic diversity, then natural selection can cause sufficient genetic chanfe to produce new species from old ones

Which factor most likely caused animals and plants in India to differ greatly from species in nearby southeast Asia?

India was a separate continent until 45million years ago

An individual mixotroph loses its plastids, yet continues to survive. Which of the following most likely accounts for its continued survival?

It engulfs organic material by phagocytosis or by absorption

What should be true of the cell wall of this bacterium?

It has an outer membrane of lipopolysaccharide

What is true of the fossil record of mammalian record?

It includes transitional forms with progressively specialized teeth

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 coloniies and produce oxygen

Which of the following is (are) true of natural selection?

It requires genetic variation, results in descent with modification, and it involves differential reproductive success

Which of the following traits do archaeans and bacteria share?

Lack of a nuclear envelope and presence of plasma membrane

Which of these provides evidence of the common ancestry of all life?

Near universality of the genetic code

When a person gets dehydrated while exercising on a hot day, their pituitary gland releases ADH, a hormone that signals the kidneys to retain more water. This is an example of -

Negative feedback regulation

A researcher discovered a species of moth that lays its eggs on oak trees. Eggs are laid at two distinct times of the year: early in spring when the oak trees are flowering in midsummer when flowering is past. Caterpillars from eggs that hatch in spring feed on oak flowers and look like oak flowers. But caterpillars that hatch in summer feed on oak leaves and look like oak twigs. How do the same population of moths produce such different-looking caterpillars on the same trees? To answer this question, the biologist caught many female moths from the same population and collected their eggs. He put at least one egg from each female into eight identical cups. The eggs hatched, and at least two larvae from each female were maintained in one of the four temperature and light conditions listed below. Temperature Day Length Springlike Summerlike Summerlike Springlike Summerlike Summerlike In each of the four environments, one of the caterpillars was fed oak flowers, the other oak leaves. Thus, there were a total of eight treatment groups. (4 environments x 2 diets) Recall the caterpillar experiment in which caterpillars born in the spring looked like flowers, and caterpillars born in the summer looked like twigs. What is the most likely selective advantage for this difference in body shape?

Looking like their food source lets the caterpillars blend into their surrounding, reducing predation

You are given four test tubes, each containing an unknown protist, and your task is to read the following description and match these four protists to the correct test tube. When light, especially red and blue light, is shone on the tubes, oxygen bubbles accumulate on the inside of test tubes 1 and 2. Chemical analysis of test tube 1 indicates the presence of a chemical that is toxic to fish and humans. Chemical analysis of test tube 2 indicates the presence of substantial amounts of silica. Microscopic analysis of organisms in test tubes 1, 3, and 4 reveals the presence of permanent, membrane-bounded sacs just under the plasma membrane. Microscopic analysis of organisms in test tube 3 reveals the presence of an apicoplast in each. Microscopic analysis of the contents in test tube 4 reveals the presence of one large nucleus and one small nucleus in each organism. Test tube 3 contains a -

Plasmodium

A localized group of organisms that belong to the same species is called -

Population

When a mosquito infected with plasmodium first bites a human, the plasmodium -

cells infect the human liver cells

In a hypothetical environment, fishes called pike-cichlids are visual predators of large, adult algae-eating fish (in other words, they locate their prey by sight). The population of algae-eaters experiences predatory pressure from pike-cichlids. Which of the following is least likely to result in the algae-eater population in future generations?

Selection for larger female algae-eaters, bearing broods composed of more, and larger, young

The loss of ventral spines by modern freshwater sticklebacks is due to natural selection operating on the phenotypic effects of Pitx 1 gene -

Silencing (loss of expression)

Parasitic species tend to have simple morphologies. Which of the following statements best explains this observation?

Simple morphologies convey some advantage in most parasites

Currently, two extant elephant species (x and Y) are classified in the genus Loxodonta, and a third species (Z) is placed in the genus Elephas. Thus, which statement should be true?

Species X and Y share a greater number of homologies with each other than either does with species Z

Which branch of biology is concerned with naming and classifying of organisms?

Taxonomy

All animals with eyes or eyespots that have been studied so far share a gene in common. When mutated, the gene Pax-6 causes lack of eyes in fruit flies, tiny eyes in mice, and missing irises (and other eye parts) in humans. The sequence of Pax-6 in humans and mice is identical. There are so few sequence differences with fruit fly Pax-6 that the human/mouse version can cause eye formation in eyeless fruit flies, even though vertebrates and invertebrates last shared a common ancestor more than 500 million years ago. The appearance of Pax-6 in all animals with eyes can be explained in multiple ways. Based on the information above, which explanation is most likely?

The Pax-6 gene was an innovation of an ancestral animal of the early Cambrian period. Animals with eyes or eyespots are descendants of this ancestor.

A biologist studied a population of squirrels for fifteen years. During that time, the population was never fewer than thirty squirrels and never more than forty-five. Her data showed that over half of the squirrels born did not survive to reproduce, because of both competition for food and predation. In a single generation, 90% of the squirrels that were born lived to reproduce, and the population increased to eighty. Which inference(s) about this most recent surge in the population size might be true?

The amount of available food may have increased and/or the predators that prey upon squirrels may have decreased

Which of the following best describes what occurred after the publication of Charles Darwin's On the Origin of Species?

The book was widely discussed and disseminated.

why do adult urochordates (tunicates) lack notochords, even though larval urochordates have them? Larvae use notochords to -

aid in swimming; adults are sessile and thus no longer propel themselves

A researcher discovered a species of moth that lays its eggs on oak trees. Eggs are laid at two distinct times of the year: early in spring when the oak trees are flowering in midsummer when flowering is past. Caterpillars from eggs that hatch in spring feed on oak flowers and look like oak flowers. But caterpillars that hatch in summer feed on oak leaves and look like oak twigs. How do the same population of moths produce such different-looking caterpillars on the same trees? To answer this question, the biologist caught many female moths from the same population and collected their eggs. He put at least one egg from each female into eight identical cups. The eggs hatched, and at least two larvae from each female were maintained in one of the four temperature and light conditions listed below. Temperature Day Length Springlike Summerlike Summerlike Springlike Summerlike Summerlike In each of the four environments, one of the caterpillars was fed oak flowers, the other oak leaves. Thus, there were a total of eight treatment groups. (4 environments x 2 diets) recall that eggs from the same female were exposed to each of the eight treatments used. This aspect of the experimental design tested which of the following hypothesis?

The differences are genetic. A female will either produce all flowerlike caterpillars or all twig-like caterpillars.

According to the endosymbiotic theory with mitochondria, 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 cell with ATP

A researcher discovered a species of moth that lays its eggs on oak trees. Eggs are laid at two distinct times of the year: early in spring when the oak trees are flowering in midsummer when flowering is past. Caterpillars from eggs that hatch in spring feed on oak flowers and look like oak flowers. But caterpillars that hatch in summer feed on oak leaves and look like oak twigs. How do the same population of moths produce such different-looking caterpillars on the same trees? To answer this question, the biologist caught many female moths from the same population and collected their eggs. He put at least one egg from each female into eight identical cups. The eggs hatched, and at least two larvae from each female were maintained in one of the four temperature and light conditions listed below. Temperature Day Length Springlike Summerlike Summerlike Springlike Summerlike Summerlike In each of the four environments, one of the caterpillars was fed oak flowers, the other oak leaves. Thus, there were a total of eight treatment groups. (4 environments x 2 diets) In every case, caterpillars that feed on oak flowers look like oak flowers. In every case, caterpillars that were raised on oak leaves looked like twigs. These results support which of the following hypothesis?

The longer day lengths of summer trigger the development of twig-like caterpillars.

Which of the following statements is FALSE regarding the complexity of biological systems?

Understanding the chemical structure of DNA reveals how it directs the functioning of a living cell.

Claytonia Virginica is a woodland spring herb with flowers that vary from white to pale pink to bright pink. Slugs prefer to eat pink-flowering over white-flowering plants (due to chemical differences between the two) and plants experiencing severe herbivory are more likely to die. The bees that pollinate this plant also prefer pink to white flowers, so that Claytonia with pink flowers have greater relative fruit set than Claytonia with white flowers. A researcher observes that the percentage of different flower colors remins stable in the study population from year to year. Given no other information, if the researcher removes all slugs from the study population, what do you expect to happen to the distribution of flower colors in the population over time?

The percentage of pink flowers should increase over time

Which of these observations gives the most support to the endosymbiotic theory for the origin of eukaryotic cells?

The similarity in size between the cytosolic ribosomes of prokaryotes and the ribosomes within mitochondria and chloroplasts

What is true of the Cambrian explosion?

There are fossils of animals in geological strata that are older than the Cambrian explosion.

Which of the following describes all existent bacteria?

Tiny, uniquitous, metabolically diverse

A farmer uses triazine herbicide to control pigweed in his field. For the first few years, the triazine works well and almost all the pigweed dies; but after several years, the farmer sees more and more pigweed. Which of these explanations best explained what happened?

Triazine-resistant weeds were more likely to survive and reproduce

Which of the following scientists argued that variation among individuals allows evolution to occur?

Wallace

You find yourself standing next to a beautiful rose bush. Which of the following do you and the rose have in common?

You both are multicellular

what is the primary function of stems?

maximization of photosynthesis by leaves

Paulinella chromatophora is one of the few cercozoans that is autotrophic, carrying out aerobic photosynthesis with its two elongated "cyanelles." The cyanelles are contained within vesicles of the host cell, and each is derived from a cyanobacterium, though not the same type of cyanobacterium that gave rise to the chloroplasts of algae and plants. The closest living relative of P. Chromatophora is the heterotroph P. ovalis. P. Ovalis uses threadlike pseudopods to capture its prey, which it digests internally. which of the following, if observed, would be the best reason for relabeling P. chromatophora as a mixotroph instead of an autotroph?

a vacuole with food inside

Which of the following characteristics is shared by a hagfish and a lamprey?

a well-developed notochord

Suppose, while out camping in a forest, you found a chordate with a long, slender, limbless body slithering across the ground near your tent. This critter could be -

an amphibian

plant meristematic cells -

are undifferentiated cells that produce new cells

a plant that grows one year, dies back, and then grows again the following year, produces flowers nd then dies would be considered -

biennial

Cotton-topped tamarins are small primates with tufts of long white hair on their heads. While studying these creatures, you notice that males with longer hair get more opportunities to mate and father more offspring. To test the hypothesis that having longer hair is adaptive in these males, you should -

determine is hair length is heritable

Giardia intestinalis is an intestinal parasite of humans and other mammals that causes intestinal ailments in most people who ingest the cysts. Upon ingestion, each cyst releases two motile cells, called trophozoites. These attach to the small intestine's lining via a ventral adhesive disk. The trophozoites anaerobically metabolize glucose from the host's intestinal contents to produce ATP. Reproduction is completely asexual, occurring by longitudinal binary fission of trophozoites, with each daughter cell receiving two haploid nuclei (n = 5). A trophozoite will often encyst as it passes into the large intestine by secreting around itself a case that is resistant to cold, heat, and dehydration. Infection usually occurs by drinking untreated water that contains cysts. The cysts of Giardia function most like the ____

endospores of bacteria

All protists are -

eukaryotic

A swim bladder is a gas-filled sac that helps fish maintain buoyancy. The evolution of the swim bladder from lungs of an ancestral fish is an example of -

exaptation

reinforced, threadlike pseudopods that can perform phagocytosis are generally characteristics of -

forams

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

have three or four membranes

some of the largest leaves in the world can be found on plants near the forest floor of dense tropical rain forests. Which of the following precursors for photosynthesis is most likely limited in these large leaves?

light

to reproduce, many plants produce seeds-structures containing embryonic offspring along with nutrients inside a tough case. These offspring develop after being released by the parent plant. To which animal reproductive strategy is seed production most comparable?

oviparouus reproduction

You are given four test tubes, each containing an unknown protist, and your task is to read the following description and match these four protists to the correct test tube. When light, especially red and blue light, is shone on the tubes, oxygen bubbles accumulate on the inside of test tubes 1 and 2. Chemical analysis of test tube 1 indicates the presence of a chemical that is toxic to fish and humans. Chemical analysis of test tube 2 indicates the presence of substantial amounts of silica. Microscopic analysis of organisms in test tubes 1, 3, and 4 reveals the presence of permanent, membrane-bounded sacs just under the plasma membrane. Microscopic analysis of organisms in test tube 3 reveals the presence of an apicoplast in each. Microscopic analysis of the contents in test tube 4 reveals the presence of one large nucleus and one small nucleus in each organism. test tube 4 contains -

paramecium

Which of the following represents an idea that Darwin learned from the writings of Thomas Malthus?

populations tend to increase at a faster rate than their food supply normally allows

Dinoflagellates -

possess two flagella

Which of the following is a characteristic of all chordates at some point during their life cycle?

post-anal tail

what is believed to be the most significant result of the evolution of the amniotic egg?

tetrapods were no longer tied to the water for reproduction

which structure of the amniotic egg most closely surrounds the embryo?

the amnion

Catastrophism was Cuvier's attempt to explain the existence of -

the fossil record

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

their mode of nutrition

Which of the following is characteristics of ciliates?

they are often multinucleate

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

Fossils of Lystrosaurus, a dicynodont therapsid, are most common in parts of modern-day South America, South Africa, Madagascar, India, South Australia, and Antarctica. It apparently lived in arid regions, and was mostly herbivorous. It originated during the mid-Permian period, survived the Permian extinction, and dwindled by the late Triassic, though there is evidence of a relict population in Australia during the Cretaceous. The dicynodonts had two large tusks, extending down from their upper jaws; the tusks were not used for food gathering, and in some species were limited to males. Food was gathered using an otherwise toothless beak. Judging from the fossil record, these pig-sized organisms were the most common mammal-like reptiles of the Permian. Anatomically, Lystrosaurus -

was a tetrapod