Life Science Exam no. 5 (final exam) – Flashcards

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A scientific hypothesis has
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It is falsifiable
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A scientific theory is
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an explanation supported by a very large amount of experimental evidence
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What hypothesis was tested by Warren and Marshall during their research involving Helicobacter pylori bacteria and stomach ulcers?
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The cause of many stomach ulcers is the bacterium H. pylori, not spicy food.
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If an inductively reasoned hypothesis makes sense, based on all available and historical observations, then
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the hypothesis might be false
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Why are hypotheses never always accepted by scientists
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Alternative hypotheses might provide a better answer to the research question
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Which of the following is a testable hypothesis
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Avoiding contact with other people reduces the chance of catching a cold.
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Mehran has heard from some of his teammates that drinking a high protein supplement after football training will improve his muscle mass. He decides to test this hypothesis by comparing the muscle mass of teammates who drink the high protein drink with a control group who drink only water. Which of the following would be the best control for his experiment?
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randomly selected teammates in training who are given a placebo instead of a protein drink
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The most effective control subjects in a test of an experimental treatment are
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treated the same as experimental subjects but not given the experimental treatment.
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The purpose of double-blind experiments is to
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minimize the effects of human bias on the results
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There is a strong correlation between stress and susceptibility to colds. This means that
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stress might or might not affect susceptibility to colds
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The specialized branch of mathematics that is used to compare data is called
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statistics
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When an experiment has a large sample size, and there is a large difference between the results in the experimental and control groups, it is ________ that the experimental results are statistically significant.
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very likely
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If the reported confidence interval for a population mean is 95%, then there is a
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95% probability that the true mean is in the reported range.
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What does it mean to say that experimental results are peer reviewed?
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The results are analyzed by other scientists before they are published.
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A news report on CNN that describes recently published research on a new treatment for colds is an example of a(n)
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secondary source.
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The most trustworthy source of scientific information is
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peer-reviewed research publications
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According to scientific evidence, what is the best prevention method known for reducing the chance of contracting a common cold
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washing your hands frequently and effectively
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Because the electrons in a water molecule are shared unequally between hydrogen and oxygen, water is said to be
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polar.
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Imagine a newly discovered biological molecule that is mostly hydrophobic in its structure. This new molecule will most likely be classified as a
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lipid.
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How do the concentrations of H+ and OH- compare to each other in an acidic solution?
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The concentration of H+ is higher
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A solution with a pH of 2 has an H+ ion concentration that is ________ than a solution with a pH of 4.
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100 times higher
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What is the name of a molecule composed of one or more sugars?
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carbohydrate
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Proteins are polymers of
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amino acids
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Which organelle contains digestive enzymes that degrade a variety of macromolecules?
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lysosome
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Which organelle is found in plant cells but not in animal cells?
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chloroplast
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Which organelle performs photosynthesis?
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chloroplast
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Which organelle performs cellular respiration?
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mitochondrion
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Cells contain proteins that help transport substances from the exterior to the interior of the cell. Where are these proteins found?
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plasma membrane
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Which organelle is represented by a network of membranes involved in the production of proteins?
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endoplasmic reticulum
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Microtubules, microfilaments, and intermediate filaments compose what part of a cell
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cytoskeletal elements
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What kind of molecule forms a bilayer that is the basis for all cellular membranes
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phospholipid
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Which feature is found in both prokaryotic and eukaryotic cells?
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DNA
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According to the theory of evolution, which states that all life-forms on Earth arose from a common ancestor, all living organisms
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share a common organic chemistry
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The plasma membrane of a photosynthetic eukaryotic cell
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isolates the cell's contents from the external environment.
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Which of the following is a lipid?
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cholesterol
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Nutrients that the human body requires in large quantities are called
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macronutrients.
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When you compare tap water to bottled water, in most cases
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bottled water and tap water are equally clean.
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Which macronutrient is the major source of energy for cell processes?
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carbohydrates
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Table sugar (sucrose) belongs to which category of nutrients?
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carbohydrates
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Why are whole foods better for your health than processed foods?
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Processed foods don't contain all the vitamins and minerals found in whole foods
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Carbohydrates are an excellent source of energy for the body. If a candy bar and a pear contain an equal number of calories from carbohydrates, which is a healthier food and why?
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The pear is healthier because it contains more vitamins, minerals, and fiber.
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Erin wants to make a stir fry using an unsaturated fat. Sam suggests that she use
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olive oil
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Vitamins in the human body
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help enzymes function properly.
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Sunlight is required for the synthesis of
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vitamin D.
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Which of these statements is true about minerals?
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Minerals cannot be made by the body
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What is a function of antioxidants?
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to decrease damage done to cells by free radicals
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Which of the following best describes the structure of the plasma membrane?
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a double layer of lipids with proteins embedded in it
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What does hydrophobic mean?
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repelled by water
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What happens to excess protein in the body?
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It is stored as fat.
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What is a major difference between saturated and unsaturated fats?
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Unsaturated fats contain carbon-to-carbon double bonds, but saturated fats don't.
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Eating large amounts of food, followed by self-induced vomiting, is a type of eating disorder called
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bulima
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Which of the following is associated with obesity?
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Type 2, noninsulin-dependent diabetes mellitus
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What term describes a harmless, noncancerous or precancerous tumor?
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benign
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Which of these people is most likely to use the most Calories during 20 minutes of exercise?
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a 30-year-old man who weighs 250 pounds
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An infinite variety of enzymes and other proteins could be produced from the ________ amino acids in the human body.
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20
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Why isn't a BMI (Body Mass Index) a perfectly reliable way to estimate your health?
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It doesn't account for differences in muscle mass between individuals.
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What is the name for the region toward the middle of a replicated chromosome where sister chromatids are connected?
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centromere
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HeLa cells
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were derived from a cancerous tumor in Henrietta Lacks
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What is the correct order of events in the cell cycle?
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G1, S, G2, mitosis, cytokinesis
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During which part of mitosis does the nuclear envelope break down?
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prophase
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What is the name of the process by which cancer cells break off of tumors and spread to other parts of the body?
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meteastasis
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________ is the cause of about one-third of all cancer deaths.
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Smoking tobacco
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What are the two halves of a duplicated chromosome called?
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sister chromatids
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During which phase of mitosis do sister chromatids separate to opposite poles of the cell?
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anaphase
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Why do chromosomes resemble the letter X when viewed during metaphase?
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Because there are two sister chromatids joined at a point in the middle (the centromere).
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What is the difference between oncogenes and proto-oncogenes?
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Proto-oncogenes encode proteins that help a cell divide under favorable conditions; oncogenes encode proteins that help a cell divide under unfavorable conditions.
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Consider a cell that underwent mitosis but not cytokinesis. The result would be
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a cell with two nuclei.
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A cell plate forms during which process?
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cytokinesis in a plant cell
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During which phase of mitosis are the replicated chromosome aligned in the middle of the cell?
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metaphase
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A gene that encodes a protein necessary for a cell to stop at checkpoints is an example of a(n)
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tumor-suppressor gene.
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The surgical removal of cells, tissue, or fluid that will be analyzed to determine whether they are cancerous is called a ________.
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biopsy
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Different versions of the same gene are called
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alleles.
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The multiple-hit model of cancer means that
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multiple mutations are required to cause most forms of cancer.
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Normal sperm or egg cells in a human
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have one copy of each chromosome
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A normal human cell containing 22 autosomes and a Y chromosome is a(n)
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sperm cell.
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Sister chromatids separate during
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meiosis II and mitosis.
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Homologous chromosomes separate during
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meiosis I.
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Crossing over occurs during
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prophase I of meiosis I.
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The members of a pair of chromosomes (for example, the two copies of chromosome 1) are called
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homologous chromosomes.
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A mistake made during copying of genetic information is called a
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mutation
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Monozygotic (identical) twins are the result of
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one embryo splitting to become two embryos.
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How does crossing over increase genetic diversity?
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Crossing over increases the number of distinct combinations of genes that may be present in a gamete.
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Mutations are only passed from parent to child if the mutation occurs in the gonads that will be used to produce
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a gamete.
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Which if the following is the correct sequence of how an animal is "built"?
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meiosis → fertilization → zygote → embryo
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As a result of 25% of FF, 50% of Ff and 25% of ff; How many different types of offspring (genotypes) are possible as a result of this cross, according to the Punnett square?
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3
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A mutation in a gene
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might have no effect on the protein encoded by the gene.
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If the DNA contained in the chromosomes of an organism is similar to an instruction manual, then what are the genes "instructing" the cell to do?
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synthesize specific proteins from amino acids
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Combined, your parents could have produced as many as ________ different types of children, genetically speaking.
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64 trillion
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In humans, heterozygotes are referred to as ________, particularly when the recessive allele is associated with a genetic disease.
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carriers
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Which of these describes influence on a trait that is due to genes and not environment?
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Jen has brown hair, just like her mother and father.
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Cystic fibrosis is caused by the allele f, which is completely recessive to the normal dominant allele F. Consider a couple with the genotype Ff. What is the chance that their second child will develop cystic fibrosis?
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25%
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Huntington's disease is caused by the allele H, which is completely dominant to the normal recessive allele h. Consider a couple where the man has the genotype Hh, and the woman has the genotype hh. What is the chance that their first child will develop Huntington's disease?
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50%
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An individual who is a carrier for a recessive genetic disorder but does not have symptoms of the disorder is
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heterozygous
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Consider a trait that shows continuous variation. If the variance is low, then
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the majority of individuals will be very close to the mean.
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If the estimated heritability of a trait is approximately 0.50, then
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at least 50% of the variation in the trait in the population is due to genetic differences.
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A scientist studying the heritability of IQ would expect to find the highest correlation between the IQ scores of
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monozygotic twins.
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Which of these conditions is caused by nondisjunction of autosomal chromosomes?
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Trisomy 21 — Down syndrome
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A normal human cell containing 22 autosomes and a Y chromosome is a(n)
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sperm cell.
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A normal human cell containing 44 autosomes and two X chromosomes is a(n)
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somatic cell of a female.
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Which of the following pairs of people would provide the most useful information to geneticists, regarding the heritability of a certain trait?
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monozygotic twins separated into different households soon after birth
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There are NO sugars on the surface of any of the red blood cells for which blood type?
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type O
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A woman with type AB blood has sugars on what percent of her red blood cells?
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100%
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A child with type O blood could not have a parent with type ________ blood.
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AB
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People with the same blood type
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may or may not be related.
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A patient with which blood type can donate to anyone?
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type O
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A patient with which blood type can receive blood from any donor?
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type AB
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A woman with type AB blood and a man with type O blood have a child. Which type of blood could the child have?
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type A or type B
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Describing a person as having hemophilia is to indicate his or her
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phenotype
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In addition to excessive bleeding, persons with hemophilia may have excessive bruising, pain and swelling in the joints, vision loss, anemia, or neurological problems. This is a result of the effects of a single gene loss and is called
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pleiotropy
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Sex-linked traits can be expressed in
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either males or females.
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Hemophiliacs have blood that does not coagulate well, and they often die at a young age. The disease allele is recessive and X-linked. Which of the following is the BEST prediction about the offspring of a hemophiliac male and a nonhemophiliac female who is a carrier for the disease?
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Some males and females could be hemophiliac.
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Hemophilia is a genetic disease that has plagued the royal houses of Europe. The disease allele is recessive and X-linked. Queen Victoria was a carrier, and her granddaughter Alexandra married Nicholas II, the last czar of imperial Russia. Alexandra was a carrier for hemophilia; Nicholas was normal. Their son, Alexis, was afflicted with the disease. Alexis and his four sisters were killed in 1917. It's most likely that
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at least one of the sisters was a carrier of the allele.
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Hemophilia is an X-linked recessive allele causing a blood disorder. What are the chances that a daughter of a normal man and a woman, who is heterozygous for the disease, will have hemophilia?
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0%
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Y-linked genes include a gene that produces hairy ears. A male with hairy ears should pass this trait
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only to his sons.
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In humans, the sex of the offspring is ordinarily determined by the
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sex chromosome carried by the sperm cell.
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A human sperm cell receives autosomes and
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either an X or a Y chromosome.
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Humans possess
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1 pair of sex chromosomes and 22 pairs of autosomes.
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When comparing the DNA fingerprints of a parent and child, the parent's DNA fingerprint will have which of the following genetic traits?
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DNA bands that match those in the child's fingerprint and that aren't from the other parent
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The polymerase chain reaction (PCR) is used to
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make many copies of a small amount of DNA.
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In DNA fingerprinting, amplified fragments of DNA are separated from one another by which process?
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electrophoresis
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A DNA molecule consists of
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nucleotides.
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A sequence of DNA codes for a
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protein.
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The structure of a protein is determined by
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the sequence of the amino acids it contains.
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The sequence of events in the process of protein synthesis is
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DNA → RNA → protein.
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The process of copying a sequence of DNA nucleotides into a complementary sequence of RNA nucleotides is called
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transcription.
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The process of copying a sequence of RNA into a protein is called
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translation.
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Milk production in modern dairy cows has been dramatically increased because of
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recombinant bovine growth hormone.
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If the process of protein synthesis in a cell is analogous to a politician's speech being written down by a reporter and then converted into a different language before being published, then the initial step (being written down by a reporter) corresponds to
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transcription
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Recombinant proteins refer to proteins that have been made in which manner?
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by genetically modified bacteria
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Genetically modifying crop plants can do which of the following?
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make the plants more resistant to freezing.
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Genetically modified foods have resulted in
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rice that allows greater synthesis of vitamin A because it has β-carotene
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A recombinant Ti plasmid can be used to
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insert genes from any source into a plant.
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The possibly harmful environmental effects of GM foods includes
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the transfer of genetically modified genes to weedy relatives
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Genetically modified tomatoes have been designed with which purpose in mind?
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having a longer shelf life in grocery stores
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What are genetically modified organisms (GMOs) also called?
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transgenic organisms
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Approximately ________ of the foods in American grocery stores contain at least small amounts of GMOs
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50%
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Fears about GMO crops were amplified when
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Monarch butterflies appeared to die off as well as insect pests.
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Data from the Human Genome Project might help scientists
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understand who might be susceptible to certain diseases.
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The raw data from the human genome project consists of
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the order of the bases A, T, G, and C in human DNA.
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The genomes have been sequenced of
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The Ebola virus.
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What is an example of gene therapy?
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infecting a cystic fibrosis patient with a virus carrying a working copy of the cystic fibrosis gene
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Which type of disease condition would most likely be successfully treated by gene therapy?
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a disease caused by a nonfunctional enzyme in the body
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The undifferentiated cells that can be used in therapeutic cloning are
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stem cells.
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Stem cells can be found in
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Cord blood.
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Therapeutic cloning aims to produce ________ from stem cells.
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healthy tissues
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The famous sheep "Dolly" was the result of
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nuclear transfer.
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Different versions of the same gene are called
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alleles
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This disease has been treated by gene therapy
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Hemopohilia and Cystic Fibrosis
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What molecule remains in the nucleus during protein synthesis?
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DNA
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What is the function of tRNA (transfer RNA) molecules during translation?
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They carry amino acids to the ribosome.
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Students studying a population of salamanders in a pool mark each salamander caught as it's entering the pool. During the first spring migration to the pool, the students mark 200 salamanders. The following year, they again capture 200 salamanders. Of these, 20 were from the previous year. Students use this information to calculate that they captured ________ of the
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10%; 2000
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The evenly spaced distribution of stalks of corn planted in an agricultural field is considered
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an uniform distribution
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Red maple tree seeds are dispersed by the wind. This species of tree can be found in fields, woods, and even wetlands. This is an example of a ________ distribution.
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random
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A population that's exhibiting exponential growth
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will have growth proportional to the current total.
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In a particular county, there are 30 births and 20 deaths for every 1000 residents. What is the annual growth rate of this population?
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1.0%
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Over the past two centuries, the growth of human population has
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increased exponentially.
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As the Industrial Revolution took place, there was a decrease in infant mortality, resulting in
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an increase in the population growth rate.
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When considering the growth of the human population, how is the annual growth rate determined?
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the number of births averaged over the population as a whole minus the number of deaths averaged over the population as a whole
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True or false: In general, developed countries have lower population growth rates than less developed countries.
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true
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When you look at the spacing of humans on a global level, the population follows a(n) ________ distribution
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clumped
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Approximately how many people are on Earth today?
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7.2 billion (7,200,000,000)
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A death rate of 2.1% would represent 21 deaths per ________ individuals in a population per year
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1000
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Developed countries are characterized by
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industrial economies and high individual incomes.
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Increased mortality in a population due to increased competition for water is the effect of
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density-dependent factor.
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Scientists calculate the carrying capacity of the earth is nearly ________ people.
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21 billion
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A population has reached the carrying capacity of the environment when
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the environment can't support a further increase in the population.
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Growth rates appear to be declining in many human populations because
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educated women are choosing to have fewer children.
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Americans make up less than ________ of the total human population, yet use close to ________ of the world's resources.
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5%; 25%
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The current rapid loss of species is considered by many scientists to be another mass extinction. This increase in extinction rate, beyond background extinction, is thought to be due to
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human population growth and the resulting habitat changes worldwide
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Fenway Park, home of the Boston Red Sox, is situated on land that was once a fen, a kind of wetland. The replacement of the fen is an example of
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habitat destruction
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) Purple loosestrife is a beautiful, long-stemmed wetlands species brought to the United States from Europe as an ornamental plant. In the United States, it has no predators and crowds out cattails, another wetlands plant that's a valuable resource for many species. Purple loosestrife is an example of
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an introduced species.
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The North Atlantic Right Whale was called the "right whale" because they were the best whale for early whalers to kill. They have long baleen and lots of blubber and oil. When killed, they could be towed back to land for processing because they float. They once numbered in the millions, but the entire population of the species is now less than 400. The history of the right whale is an example of
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overexploiation
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The World Wildlife Federation recently reported that the number of animals world-wide has decreased by _________% in the last 40 years
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50
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There have been ________ mass extinctions experienced on a global scale before the alarming mass extinction that's now occurring.
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five
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North America is currently experiencing an unprecedented and rapid loss of species. What is believed to be the main trigger of such events, either directly or indirectly?
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increased human population
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What law was passed to address the problem of rapid species loss in the United States?
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the Endangered Species Act of 1973
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The variety of species in an area of interest is called
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biodiversity
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The average lifespan of a species on Earth is estimated to be around ________ years.
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1,000,000
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What presents the greatest threat to biodiversity?
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habitat loss or degradation
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Which of the following threats to biodiversity isn't directly due to humans?
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loss of habitat due to volcanic activity
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The runoff of fertilizers from agricultural and residential areas can cause the aquatic algae in bodies of water to grow prolifically, resulting in a phenomenon called
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eutrophication
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"Colony collapse disorder" is thought to be due to an increase in ________ of honeybees.
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parasites
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Ants live in bull's horn acacia trees. The ants will attack any predators of the tree. In return, the ants live protected in the thorns of the tree and eat the nectar and protein-rich secretions of the tree. This is an example of
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mutualism
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Cattle egrets hitch a ride on domestic cows and eat insects that are stirred up by their activity. This is an example of
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commensalism
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A woman is more susceptible to vaginal yeast infections when taking antibiotics because
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the normal bacteria in the vagina are also killed by the antibiotic and can't competitively exclude the yeast
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Extracts of the rosy periwinkle have provided drugs now available for treating cancer. The ability to find this species of plant and discover these drugs is a strong argument for
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preserving biodiversity
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During the 1980s, wolves were reintroduced to Yellowstone National Park after decades of absence due to extermination. Within 20 years, not only had the wolf population increased, but there was also a dramatic increase in other species, such as aspen, cottonwood, and willow trees, beavers, warblers, insects, and fish. This is an examples of how important a(n) ________ is.
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keystone species
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Salmonella causes a food-borne illness that kills Americans each year. It is found mainly in poultry products. Rather than give large doses of antibiotics to poultry, some poultry producers infect the intestinal tract of hens with a harmless bacteria, resulting in a dramatic decrease of Salmonella found in the chickens. The producers have used the principle of
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competitive exclusion.
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There is an article in your local newspaper about an upcoming "Biodiversity Day" event at your university. Because you understand why it's important to conserve biodiversity after studying biology, you plan to attend. Your younger brother tells you he doesn't understand how the loss of a few species or habitats in town can have any impact on anyone's life. You could tell him
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a decrease in biodiversity could result in a loss of species that could provide humans with new drugs to cure disease.
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A species that has a high number of alleles for many genes that are distributed throughout the population is said to have
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high genetic variability
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) Is a species that has few individuals at greater risk of extinction than a species with a large population size? Why or why not?
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Yes. A species with few individuals is more likely to be eliminated by a reduction in population size caused by a chance environmental event like bad weather or a fire.
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Los Angeles, California, has an average daily temperature between 70° F and 80° F throughout most of the year. There's very little rainfall except for during a rainy season beginning in the fall. This describes the city's
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climate
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What city would have the largest variation in daylight hours between the summer solstice and the winter solstice?
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Montreal, Canada
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Compared to the air above a nearby land mass, the air above a large body of water is
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cooler in summer.
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Which of the terrestrial biomes is dominated by woody plants?
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chapparal
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When all living organisms are included, ________ contain about 70% of the biomass found on Earth's land surface
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forests
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What type of land biome is commonly found at 30 degrees North and 30 degrees South?
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desert
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When a patch of land is cleared in a tropical rainforest, the vegetation is often burned to enrich the soil with nutrients from the burned plant material. This
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works for a few years, but the soil is soon depleted of nutrients.
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Coniferous trees are most abundant in
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boreal forests
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An environment where the plants are low to the ground and many boggy areas are found is called
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a tundra
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