BI101J, UNSEEN LIFE ON EARTH—MIDTERM EXAM 1 Darwin and Wallace's ideas about evolution include life had a common origin. there is variation within populations. the environment constantly changes and competition between individuals results in the selection of favorable traits within the environment. * all of the above none of the above Critique this sentence: Most mutational changes damage a protein's function. * True; a change in the sequence of DNA, called a mutation, will result in a change in the sequence of amino acids in the protein coded for by that gene. And yes, most changes are harmful. True; mutations are changes in the amino acid "language" found in our genes and they result in changes to the nucleic acid sequence found in proteins. False; most mutations are beneficial. False; mutations don't have anything to do with protein function. none of the above Critique this sentence: We expect the microbial world to be rich and complex. True; the incredible diversity of bacterial shape is truly astounding; there are millions of different-appearing microbes. * True; microbes have been fine-tuning and evolving for billions of years, and regardless of their apparent similarity in shape, they have many important internal differences that allow them to exploit all different environments on Earth. False; based on our current understanding of microbial life, we think there are only a small handful of different bugs out there. False; we don't know what to expect, because we are just beginning to learn about microbes. none of the above The first photosynthetic organisms were bacteria. * True False Many species of bacilli, spirilli , and a few cocci move by means of legs. arms. tentacles. suckers. * flagella. Bacterial nuclear material is surrounded by mesosome. nucleus. * cytoplasm. pilus. granule. The correct sequence of bacterial structures, starting from the outside and moving in is mesosome, nucleosome, granules, cytoplasm. * capsule, cell wall, cell membrane. cell membrane, cytoplasm, cell wall, nucleus. granule, endoplasmic reticulum, ribosome, cytoplasm. none of the above In asexual reproduction, bacteria and other microorganisms must * duplicate their DNA and other cell structures. join with another of the same species to exchange genetic material such as plasmids. synthesize new cytoplasm, but not DNA - the bug just splits what DNA it has, and later on will replenish what it lost from its food. none of the above Penicillin acts to disrupt bacterial cell division by stopping synthesis of cytoplasm. stopping synthesis of new DNA - it's a DNA synthase inhibitor. stopping production of additional cytoplasm. * inhibiting production of cell wall material. all of the above Aerobic bacteria prefer to live where oxygen is ________; anaerobic bacteria prefer ________ oxygen. * plentiful; little or no little or no; plentiful combined with iron; free combined with carbon; carbon-free none of the above Endospores of the genus Clostridium can survive in boiling water and the organism can grow in very low oxygen levels. So what? The rascal may grow in improperly canned food and produce botulism poisoning in people, that's what! The organism can grow in deep wounds, even if thoroughly washed and can cause gas gangrene or tetanus. The organism can live in soils and mud that are very low in oxygen. * all of the above Critique this sentence: We could expect to find thriving, growing populations of bacteria commonly found on Earth in outer space. * Most unlikely! Most bacteria on earth soon die if deprived of food or water, although a few will form tough, resistant stages called endospores that do indeed resist long periods of harsh conditions. We might find resting stages of bacteria in space, but there's no liquid water, so none could grow and thrive. It's not impossible, because we've found bacteria that live in extremes of temperature, pressure, and acidity. Certainly! I saw it on the X-files just last week! none of the above All organisms in this nutritional class of microorganisms harvest energy (electrons) and carbon from the same source. autotrophs * heterotrophs chemotrophs phototrophs none of the above Exponential growth of a population occurs in the ________ phase. death lag * log stationary end Using a closed container (such as a brewer's tank) for microbe cultivation means that four stages of population growth do not occur. nutrients are continually supplied. * four stages of population growth will occur. metabolic byproducts are continually removed. the brewmaster must carefully vent away the build-up of oxygen inside the tank. The term macromolecules refers to * large, complex molecules. large, complex gases, such as hydrogen or helium. smaller molecules, such as CO2. larger organisms, such as mushroom-forming fungi. smaller organisms, such as Bacillus or Clostridium. In the absence of oxygen, ________ occurs in the muscle tissue of animals. * lactic acid fermentation alcohol fermentation (can you get drunk by holding your breath?) anaerobic respiration metabolism does not proceed; the tissue dies none of the above ________ are the producers in deep sea ocean vent ecosystems. Phototrophs * Chemolithotrophs Organotrophs Heterotrophs There are no producers, only decomposers and detritivores (eaters of dead stuff). Bacteria reproduce by or when playing the lottery. accumulating DNA from others. * binary fission. they've been exposed to the proper chemical messengers. producing gametes that then fuse together. The three kinds of RNA are * messenger, transfer, and ribosomal. amino acids, phosphorylation, nucleic acids. sugar, salt, fat (also known as the three major food groups). deoxyribose, serotonin, uracil. regulatory, promoter, operons. The nucleotides of DNA consist of three parts: * a deoxyribose, a phosphate, and a nucleic acid base. a ribose, a nucleic acid base, and a phosphate. adenosine triphosphate (ATP), adenosine diphosphate (ADP), and a ribosome. all of the above none of the above The mass of living microbes is ____ compared to the mass of all other organisms. * larger smaller the same as none of the above Microbes are responsible for many characteristics of our world today, such as * the oxygen-rich atmosphere. the nitrogen-rich atmosphere. the hydrogen-rich atmosphere. the ostrich-rich atmosphere. none of the above Microbes were the ________ life forms to evolve on the planet. most recent * first second third fourth Bacteria and archaea are the ________ independent living cells. largest * smallest least numerous none of the above Biosphere 2 is the Earth. the Moon. the Sun. the other planets. * none of the above The experiment in Biosphere 2 that sealed 8 "Biospherians" inside failed because the trip planners underestimated the amount of fuel required to reach its destination. the team fell to bickering and mutinied. a fungus destroyed all the corn and wheat seeds. * its creators underestimated the complexity involved in constructing a completely sealed environment. all of the above Microbes can be found only where there is light sufficient to allow photosynthesis. only where the temperature never falls below freezing. only indoors. * nearly everywhere on Earth. none of the above Evaluate this statement: Microbes have had a relatively minor impact on human lives today and throughout human history. True; such microscopic things simply aren't large enough to influence large creatures such as ourselves. True; microbes are so rare that humans only very occasionally encounter them. True; microbes might be numerous, but they are not found where humans can live. False; microbes appeared only recently, and only in the last 50 years have we experienced major illnesses. * False; microbes have had a major influence on us throughout human history. The science of microbiology studies bacteria and archaea. viruses. fungi and algae. protozoans, flatworms, and roundworms. * all of the above Evaluate this statement: Some human disease-causing organisms may be carried by rats and fleas. False; bugs that affect other animals do not infect humans. False; while rats may carry fleas, the fleas don't bite humans. * True; the fleas can transfer disease-causing organisms from rats to humans. none of the above Humans have been harnessing microbes for thousands of years. These uses include leavening in bread. wine and beer making. cheese production. * all of the above none of the above A notable and unique feature of prokaryotic cells is the * lack of a nucleus. lack of a cell wall. lack of DNA. presence of a nucleus. presence of DNA. Which of the following groups is composed of eukaryotic cells? archaea bacteria * protozoa viruses all of the above Select the incorrect statement about viruses. * They can reproduce independently of their hosts. They contain nucleic acids. They have proteins. They lack a cellular structure. The tobacco mosaic virus infects people who smoke. True * False A disease is a ________, while a pathogen is a ________. * non-normal state in an organism; the agent responsible for that state. microbe; fungus fungus; microbe all of the above none of the above A nucleus is not found in a eukaryote. * prokaryote. fungus. animal. plant. DNA is * a molecule that contains the instructions that allows a cell to survive and reproduce. the molecular factory that makes proteins. composed of ribosomes. composed of proteins. the molecular factory that photosynthesizes. Microbes are usually measured in units such as kilometers. meters. centimeters. millimeters. * nanometers. The flagella found on many bacteria help the bug to * move around. stick to surfaces. defend themselves. contain the DNA. photosynthesize. Ribosomes are responsible for movement. sticking cells together to form biofilms. * the production of proteins. containing DNA. none of the above The nucleus is found * in all eukaryotes and it contains the genome. in all prokaryotes and it contains the genome. only in some archaebacteria. only in some mycoplasmas. in Escherichia coli. Mitochondria are responsible for * generating energy. containing DNA. movement. sticking to surfaces to form biofilms. reproduction. Most bacteria are far ________ than viruses. smaller * larger more clever smarter more dense In general, cold ________ microbial growth. favors enhances speeds up increases * none of the above Household air is free of airborne bacteria and fungi. True * False Pasteurized milk may contain bacteria. * True; but so few that it is far safer to drink than raw milk. True; it’s nearly as bug-free as raw milk. False; pasteurization completely sterilizes the milk. none of the above Factors that may contribute to the contamination of milk include general health of the animal. cleanliness of the dairy. biofilm formation in the tanker truck. * all of the above none of the above Purification of water delivered to our homes relies on * both chemical treatment and mechanical filtration. the construction of anaerobic digester tanks to produce methane. all of the above none of the above