Concept explainers
MAKE CONNECTIONS Ø The gene that causes sickle-cell disease is present in a higher percentage of residents of sub-Saharan Africa than among those of African descent living in the United States. Even though this gene causes sickle-cell disease, it also provides some protection from malaria, a serious disease that is widespread in sub-Saharan Africa but absent in the United States. Discuss an evolutionary process that could account for the different percentages of the sickle-cell gene among residents of the two regions. (See Concept 1.2.)
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Chapter 1 Solutions
Mastering Biology with Pearson eText -- Standalone Access Card -- for Campbell Biology (10th Edition)
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- Match the numbered concepts to the lettered facts. Explain why each pair is the best match. (1) Gene Duplication (2) Molecular Clock (3) Pseudogene (4) SINES and LINES a. Different kinds of globin chains arose over time including myoglobin, alpha globin, beta globin 1, delta globin, and beta globin 2.b. The two human beta globin genes, 1 and 2, differ at 20 base pair sites; only beta gene 1 produces a functional protein.c. In human hemoglobin, the delta polypeptide chain differs by 39 amino acid sites vs. the beta chain.d. The human alpha globin gene and the mouse alpha globin gene are orthologous to each other.arrow_forwardIf myoglobin is found in all chordates, urochordates, and cephalochordates, b-globin is found in all vertebrates, a-globin in all ostracoderm descendants, z-globin in all gnathostomes, e-globin in all viviparous mammals, and g-globin in all placental mammals, then the most ancient of these genes: must be epsilon-globin (e-globin), found only in descendants of the ancestral marsupials must be myoglobin, found only in descendants of the chordates, urochordates, and cephalochordates must be gamma-globin (g-globin), found only in descendants of the ancestral placentals must be zeta-globin (z-globin), found only in descendants of the ancestral gnathostome fishes must be beta-globin (b-globin), found only in descendants of the ancestral vertebratesarrow_forwardWhy do scientists believe that the sickle-cell trait has not evolved out of the human population yet considering how deadly it is to be homozygous for the sickle cell gene?arrow_forward
- If 9% of an African population is born with a severe form of sickle-cell anemia (ss), what percentage of the population will be more resistant to malaria because they are heterozygous (Ss) for the sickle-cell gene? Assume Hardy-Weinberg conditions. Submit your answer as it is. a) homozygous recessive individuals (q²) b) the recessive allele (q) c) the dominant allele (p) d) homozygous dominant individuals (p²) e) heterozygous individuals (2pq)arrow_forwardPlease match: 12345 Allele 12345 Analogous 12345 Sympatric 12345 Homologous 12345 Allopatric 1. The wing of a bat and the leg of a horse are examples of ____ structures 2. The wing of a bat and the wing of a butterfly are examples of______ structures 3. A version of a gene is called a(n) 4. Speciation that occurs when two species are together is called 5. Speciation resulting from two populations being separated by a physical barrier is calledarrow_forwardA form of dwarfism known as Ellis–van Creveld syndrome was first discovered in the late 1930s, when Richard Ellis and Simon van Creveld shared a train compartment on the way to a pediatrics meeting. In the course of conversation, they discovered that they each had a patient with this syndrome. They published a description of the syndrome in 1940. Affected individuals have a short-limbed form of dwarfism and often have defects of the lips and teeth, and polydactyly (extra fingers). The largest pedigree for the condition was reported in an Old Order Amish population in eastern Pennsylvania by Victor McKusick and his colleagues (1964). In that community, about 5 per 1000 births are affected, and in the population of 8000, the observed frequency is 2 per 1000. All affected individuals have unaffected parents, and all affected cases can trace their ancestry to Samuel King and his wife, who arrived in the area in 1774. It is known that neither King nor his wife was affected with the…arrow_forward
- PLEASE ANSWER THE QUESTION AND EXPLAIN SUCCINTLY IN 2 SENTENCESarrow_forwardIf myoglobin is found in all chordates, urochordates, and cephalochordates, b-globin is found in all vertebrates, a-globin in all ostracoderm descendants, z-globin in all gnathostomes, e-globin in all viviparous mammals, and d-globin in all eutherian mammals, then the most recent globin gene must be: myoglobin, found only in descendants of the chordates, urochordates, and cephalochordates zeta-globin (z-globin), found only in descendants of the ancestral gnathostome fishes epsilon-globin (e-globin), found only in descendants of the ancestral marsupials beta-globin (b-globin), found only in descendants of the ancestral vertebrates delta-globin (g-globin), found only in descendants of the ancestral eutheriansarrow_forwardHow many globin genes are present in mammals? What is the evidence indicating that all the globin genes in the mammalian genome are part of a family derived from a common ancestral globin gene?arrow_forward
- What is the answer to this problem? I said the answer was "Homo sapiens populations interbred with the Denisovans before leaving Africa." and this was marked wrong.arrow_forwardThe path of whale evolution has involved the reduction or loss of several traits that are still prominent in most other mammals. TRUE (1) or FALSE (2). In terrestrial mammals, the sense of smell (olfaction) involves receptor proteins encoded by a number of genes. Whales don't have a sense of smell underwater, but their genomes still contain copies (pseudogenes) of some of these olfactory genes in their genomes. Because they are still present in whales' genomes, these genes must serve some other function in whales. Whales have some vestigial features like muscles that are attached to external ears in other mammals, even though whales have lost their external ears. Humans also lost some traits (e.g., body fur) and also have some vestigial traits, such as a mechanism to cause fur to stand on end even though we are mostly hairless (i.e., arrector pili muscles that produce goosebumps). Some features like hindlimb buds and whiskers are observed…arrow_forwardMany animals have the p53 gene that makes a protein that regulates the cell cycle and helps prevent the formation of cancer cells. The table below shows the percentage of p53 gene sequences that the 4 species have when compared to humans. Species Percentage of p53 Gene Sequence Similar to Human Human 100 Horse 60.7 Fruit Fly 15.5 Rat 76.8 Pig 81.3 Which organism in the table is most closely related to humans based on this data? pig horse fruit fly rat 0 0 0 0arrow_forward
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