Fundamentals of Genetics and Molecular Biology, Exams of Biology

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BSC 108 Exam 3 with Complete Solutions

_________ evolve over time, not individual ___________ - ANSWER-populations; organisms As descendants of a common ancestor spread out into various habitats: - ANSWER- they acquired adaptations to their particular environments through natural selection Describe the carbon cycle - ANSWER-CO2 is removed from the atmosphere by photosynthesis, passed along food chain by consumers, returned to the atmosphere by cellular respiration, decomposers break down carbon compounds in dead matter, CO is eventually CO2 is released back into the atmosphere (burning fossil fuels, causing more to be released than consumed) DNA makes RNA through: - ANSWER-transcription Each strand is used as a ______________ to make a new strand. - ANSWER-template Energy is lost: - ANSWER-as heat at each transfer of energy and nutrients between trophic levels Energy: - ANSWER-flows into and out of an ecosystem How are the nitrogen-containing bases held together? - ANSWER-hydrogen bonds How can a trait be favored in one situation but not in another? - ANSWER- environmental factors vary from place to place and time to time How can new species form without geographic isolation of two populations? - ANSWER-two distinct gene pools emerge through chromosomal changes due to errors in mitosis and meiosis, habitat differentiation, or sexual selection How could a scientist genetically engineer an organism? - ANSWER-1. Isolate a bacterial plasmid and DNA of interest from another organism

2. Two are joined together, resulting in recombinant plasmids
3. Recombinant plasmids are mixed with bacteria, which "take up" the recombinant plasmids
4. Each bacterium (carrying the recombinant plasmid) reproduces via cell division to form a clone a. The foreign gene carried by recombinant plasmid is also copied
5. Transgenic bacteria with the gene of interest can then be grown in large tanks
6. Final product may be: a. Copies of the gene itself b. Product of the cloned gene

How does an organism's DNA lead to specific traits? - ANSWER-by dictating the synthesis of proteins How does DNA replicate? - ANSWER-DNA molecule unwinds and each strand is a template for complementary base pairing; each daughter helix contains an intact strand from the parent helix and a newly synthesized strand therefore DNA replication is semiconservative How does information flow in a cell? - ANSWER-DNA -> RNA -> Protein How have humans impacted biodiversity? - ANSWER-through population numbers, use of land, and lifestyles How many strands of DNA does a DNA molecule contain? - ANSWER-two Natural selection can amplify or diminish only ________ traits, not ________ traits - ANSWER-heritable; acquired Nutrients: - ANSWER-are recycled within an ecosystem One parent molecule is composed of two __________________ that separate. - ANSWER-complementary strands RNA contains ________ instead of thymine. - ANSWER-Uracil RNA makes protein through: - ANSWER-translation The two strands of DNA are: - ANSWER-complementary Two different species can evolve independently but: - ANSWER-acquire the same traits as adaptations to similar environments What are analogies (analogous structures)? - ANSWER-similarities among living organisms that are due to similar environmental pressures and natural selection (convergent evolution) What are consumers? - ANSWER-heterotrophs - consume the food made by producers What are decomposers? - ANSWER-they break down waste products and the remains of dead organisms (fungi and bacteria) What are detritus feeders? - ANSWER-organisms that consume dead organic matter What are frameshift mutations? - ANSWER-mutations caused by insertions/deletions of a number of nucleotides not divisible by 3

What are heterotrophs? - ANSWER-they can't make their own food, rely on other organisms/organic products for food (humans) What are homologies (homologous structures)? - ANSWER-similarities among living organisms that are due to shared ancestry What are potential effects of frameshift mutations? - ANSWER-completely different translation, replication ending too soon, too-long chain What are primary consumers? - ANSWER-herbivores like insects What are producers? - ANSWER-plants and other autotrophs - produce the food for an ecosystem What are secondary consumers? - ANSWER-smaller carnivores that consume herbivores What are some examples of how genetic engineering has affected agriculture and medicine? - ANSWER-herbicide resistant crops, nutritional value of crops, greater yield of crops by making them resistant to natural destroyers, vaccines, gene therapy What are some of the common uses of DNA fingerprinting? - ANSWER-to solve crimes using forensics, paternity/maternity testing, family genetics, ancient DNA/archaeology What are tertiary consumers? - ANSWER-larger carnivores that consume smaller carnivores What are the 4 types of evidence supporting the Theory of Evolution? - ANSWER- biogeographical embryological fossils DNA and biochemical evidence What are the characteristics of a coral reef? - ANSWER-"rainforests of the ocean," ¼ of marine species rely on them for food/shelter, Great Barrier Reef is world's largest living structure What are the characteristics of a lake? - ANSWER-formed by blocked or ending rivers, soil is supersaturated, water is mainly still but can be moving in some slanted areas What are the characteristics of a pond? - ANSWER-same, but doesn't have an aphotic zone (meaning there's not an area deep enough that sunlight can't reach) What are the characteristics of a river? - ANSWER-flowing freshwater, higher O2 levels than stationary waters, natural, contains channels that empty into larger bodies of water

What are the characteristics of a stream? - ANSWER-same, but smaller than a river- would flow into or out of a river What are the characteristics of a temperate forest? - ANSWER-deciduous and evergreen trees, fluctuating temperatures, defined seasons What are the characteristics of a temperate grassland? - ANSWER-temperate, not enough rain to support a forest, flat, rich soil, large number of animals What are the characteristics of a tropical grassland? - ANSWER-high amount, but not enough rain to support a forest, grasses dominate, scattered trees may be common What are the characteristics of a tropical rainforest? - ANSWER-most diverse ecosystem on Earth, near equator, high precipitation, year-round warmth, flourishing vegetation What are the characteristics of an ocean? - ANSWER-home to the smallest organisms, three zones based on amount of sunlight that can reach, large variety of plants/animals, saltwater What are the four trophic levels? - ANSWER-producers, primary consumers, secondary consumers, tertiary consumers What are the major types of ecosystems? - ANSWER-ocean, lakes, ponds, rivers, streams, coral reef, marsh, tundra, taiga, temperate forest, tropical rain forest, temperate grassland, tropical grassland, desert What are the nitrogen-containing bases in DNA? - ANSWER-adenine, guanine, thymine, cytosine What are the steps of human gene therapy? - ANSWER-Normal human gene is isolated and cloned, human gene is inserted into a virus, virus is injected into a patient, normal human gene is transcribed and translated in the patient What are the three types of symbiotic relationships? - ANSWER-parasitism, commensalism, mutualism What are the two daughter molecules composed of? - ANSWER-One "old" (parent) strand and one "new" (synthesized) strand What bases pair together? - ANSWER-adenine=thymine guanine=cytosine What can a point mutation change? - ANSWER-a gene's protein product

What can natural selection do? - ANSWER-increase the adaptation of organisms to their environment over time (camouflage) What can resource partitioning lead to? - ANSWER-an increase in the chances of survival for species who share a habitat by reducing competition for resources What did Darwin's observations of the geographic distribution of species like the Galapagos finches lead to? - ANSWER-ideas about adaptation to the environment and origin of new species What do the replication bubbles do as DNA replication progresses in both directions at the replication forks? - ANSWER-merge What does change in the DNA molecule cause? - ANSWER-altered mRNA to be transcribed and different amino acids to be added to the polypeptide chain What ideas was Darwin influenced by? - ANSWER-gradualism by Hutton and Lyell What is a community? - ANSWER-a group of populations of different species interacting with another in a single environment What is a desert? - ANSWER-low precipitation, varying temperatures, windy, rocky and/or sandy, sparse vegetation, animals highly adapted to dryness What is a food chain? - ANSWER-sequence of food transfers between trophic levels of a community, beginning with producers What is a food web? - ANSWER-a network of interconnecting food chains What is a genetic drift? - ANSWER-change in gene pool of a population due to CHANCE What is a genetically modified organism (GMO)? - ANSWER-organism that has acquired one or more genes artificially What is a marsh? - ANSWER-dominated by grasses, reeds, and sedges, type of wetland, water covers ground for long time, treeless What is a mutation? - ANSWER-change in the genetic material of a cell What is a plasmid? - ANSWER-small ring of self-replicating DNA separate from the larger chromosome(s) What is a point mutation? - ANSWER-change in one base pair of a gene

What is a polymerase chain reaction (PCR)? - ANSWER-technique used to obtain many copies of a DNA molecule What is a restriction enzyme? - ANSWER-bacterial enzyme that cuts foreign DNA at one very specific nucleotide sequence What is a species? - ANSWER-group of populations whose members possess similar anatomical characteristics and the ability to interbreed What is a stem cell? - ANSWER-a cell that generates replacements for nondividing differentiated cells What is a taiga? - ANSWER-far northern regions of the world, consist of always green needle-and-cone trees, such as pine and spruce What is a transgenic organism? - ANSWER-a GMO that has received genes from an organism from another species What is a tundra? - ANSWER-harsh, snow-covered, windy, treeless, soil frozen almost year-round, some lichens and small flowers present, birds in spring What is a vector? - ANSWER-DNA carriers that move genes from one cell to another What is adaptation? - ANSWER-a characteristic that helps and individual survive and reproduce What is adaptive radiation? - ANSWER-the evolution of diversely adapted species from a common ancestor upon introduction to a new environment What is an autotroph? - ANSWER-they can make their own food and sustain themselves (plants) What is an ecosystem? - ANSWER-a community interacting with the physical environment What is an embryonic stem cell? - ANSWER-cells in early animal/human embryo that differentiate during development to create all of the specialized cells in the body What is artificial selection? - ANSWER-purposeful breeding of domesticated plants and animals by humans (dog breeding) What is biogeographical evidence? - ANSWER-global distribution of organisms and unique features of island species can be evaluated over time What is biotechnology? - ANSWER-manipulation of organisms or their parts to produce a useful product

What is commensalism? - ANSWER-one benefits, other neither benefits nor is harmed (tree frogs use plants as protection, jackals follow tigers and eat their scraps) What is competition? - ANSWER-fight for similar required and limited resources (humans fight for resources, predators fight for prey) What is Darwin's theory of natural selection? - ANSWER-Organisms have variations, struggle to exist, and differ in fitness. Organisms that are more fit will successfully reproduce and pass on desirable variations and in this way, they will become adapted to their environments What is Darwinian fitness? - ANSWER-contribution to the next generation's gene pool, relative to the average for the population What is descent with modification? - ANSWER-all organisms are related through descent from a common ancestor these descendants spilled into various habitats over millions of years accumulated various modifications that fit them to their specific ways of life What is DNA and biochemical evidence? - ANSWER-DNA comparisons can show how related species are What is DNA composed of? - ANSWER-nucleotide subunits What is DNA fingerprinting? - ANSWER-technique that analyzes an individual's unique collection of genetic markers to determine whether two samples of genetic material came from the same individual What is embryological evidence? - ANSWER-embryos of two species can have very close resemblance, even if the adult species do not resemble each other What is fossil evidence? - ANSWER-document differences between past and present organisms What is gene therapy? - ANSWER-procedure intended to treat disease by altering an afflicted person's genes What is included in a species' ecological niche? - ANSWER-its habitat, role in the community, and interactions with other species What is mutualism? - ANSWER-each benefit from relationship (woodpeckers eat ticks from rhinos' backs, bees pollinate flowers)

What is natural selection? - ANSWER-natural differential success in reproduction among individuals that vary in heritable traits (coloration or size) What is parasitism? - ANSWER-parasite benefits, host is harmed (tick, tapeworm, lice, leech) What is predation? - ANSWER-predator kills and eats prey (humans hunting deer to eat, cat kills and eats mouse) What is recombinant DNA? - ANSWER-molecule containing DNA from two different sources What is reproductive cloning? - ANSWER-using a body cell to make one or more genetically identical individuals What is speciation? - ANSWER-evolutionary process in which one species splits into two or more species What is symbiosis? - ANSWER-a close relationship between two species What is the backbone of DNA covalently bonded to? - ANSWER-nitrogen-containing bases What is the backbone of DNA? - ANSWER-deoxyribose and a phosphate group What is the biosphere? - ANSWER-it encompasses all of the ecosystems on Earth What is the function of mRNA (messenger RNA)? - ANSWER-carries the genetic message from a gene (DNA) to ribosomes that translate it into a protein What is the function of rRNA (ribosomal RNA)? - ANSWER-to make up ribosomes with proteins What is the function of tRNA (transfer RNA)? - ANSWER-translates codons into amino acids What is the nitrogen cycle? - ANSWER-1. Planting crops adds nitrogen to the soil

2. Bacteria in soil and water fix nitrogen, resulting in NH4 (ammonium)
3. After fixed, some of the ammonium is taken up and used by plants
4. Nitrifying bacteria in soil also converts some NH4 into NO3 (nitrate) which is more often acquired by plants
5. Plants use nitrogen to make molecules such as amino acids/proteins
6. Plants are consumed, along with the nitrogen they contain
7. Decomposers decompose dead animals, releasing nitrogen into soil and atmosphere a. Humans combustion of fossil fuels and modern agricultural process are adding more nitrogen to atmosphere

b. More is being released than consumed, contributing to global warming and pollution of aquatic systems from nitrogen fertilizers What is the phosphorous cycle? - ANSWER-1. Weathering of rock adds inorganic phosphate PO4 to the soil

2. Plants absorb dissolved PO4 from soil and assimilate it by building it into organic compounds
3. Consumers obtain phosphorous by eating plants
4. Phosphates are returned to soil when decomposers decompose, and when animals produce urine/feces
5. Some phosphates drain from soil into the sea, where they may settle and become part of new rocks
6. This phosphorous will not be available to living organisms until these rocks experience weathering again a. Naturally, phosphates are moved from land to water quicker than they can be replaced b. This limits availability to plants, so farmers use phosphate fertilizers to boost plant growth What is the primary ecological succession? - ANSWER-community arises in a lifeless area with no soil What is the secondary ecological succession? - ANSWER-community arises in a lifeless area with soil What is the source of energy for the entire biosphere? - ANSWER-the sun What is the structure of a strand of DNA? - ANSWER-double helix, twisted ladder What is the structure of RNA? - ANSWER-single-stranded nucleic acid What is the structure of tRNA? - ANSWER-three leaf clover, where one loop is the anticodon and the other end is where the amino acid attaches What is therapeutic cloning? - ANSWER-reproductive cloning of human cells by nuclear transplantation What is transcription? - ANSWER-synthesis of mRNA under the direction of DNA What is translation? - ANSWER-synthesis of a polypeptide (which will become a protein) under the direction of mRNA What is tRNA's role in translation? - ANSWER-picks up amino acids and matches them to codons What sugar is used in RNA? - ANSWER-ribose

What two processes do genes code for specific proteins? - ANSWER-transcription and translation What type of adaptations could have come from adaptive radiation? - ANSWER- modifications of the ancestral anatomical structures to suit their new functions (swimming, flying, walking) Where and how does synthesis of two new complementary strands occur? - ANSWER- replication bubbles, using the parent strands as templates Where do parent strands separate? - ANSWER-origins of replication Where does transcription occur? - ANSWER-nucleus of a cell Where does translation occur? - ANSWER-on the ribosomes in the cytoplasm Where does tRNA pair with mRNA? - ANSWER-at the anitcodon