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.)
Learn your wayIncludes step-by-step video
Chapter 1 Solutions
Mastering Biology with Pearson eText -- ValuePack Access Card -- for Campbell Biology
Additional Science Textbook Solutions
Concepts of Genetics (12th Edition)
Microbiology with Diseases by Taxonomy (5th Edition)
Biology: Life on Earth
Biology: Life on Earth with Physiology (11th Edition)
Human Biology: Concepts and Current Issues (8th Edition)
Campbell Biology: Concepts & Connections (9th Edition)
- A cladogram shows the evolutionary relationship between humans, chimpanzees, and gorillas. The cladogram currently shows humans and chimpanzees with a more recent common ancestor compared to gorillas. Which piece of evidence, if true, would most likely weaken this hypothesis? Amino acid analysis of the cytochrome shows significant differences in the sequence of amino acids between humans and goriffas. DNA sequence analysis of the hemoglobin alpha gene shows that humans and chimpanzees have a more similar sequence to each other than they do to the gorilla's DNA sequence. The cells of the eye in embryos of gorillas and humans follow a similar pattern of development chimpanzee embryos are different Fossils of humans appear in deeper sedimentary rock layers compared to fossils of chimpanzees.arrow_forwardMAKE CONNECTIONS Describe how Tiktaalik’sfeatures illustrate Darwin’s concept of descentwith modification (see Concept 22.2).arrow_forwardConsidering the evolution of species, could a gene that is conserved from yeast to humans have evolved to confer some of the complex traits that we observe in modern animals, like multicellularity? Briefly explain.arrow_forward
- Recall from our classes on molecular evolution that some proteins evolve more rapidly than others. For example, the oxygen-carrying protein myoglobin evolves more quickly than the D1 protein of photosystem II. What explains this difference in the rate of protein evolution? A. Proteins like myoglobin have evolved more recently than proteins like D1 and thus have been forced to evolve more quickly. B. Changes to the sequence of some proteins can be tolerated as they don’t alter fitness; for other proteins, sequence changes are usually harmful. C. In constrained proteins like D1, evolution results primarily from nucleotide changes that alter the amino acid sequence of the protein. D. Protein evolution is dependent upon the rate of gene mutation and some genes have a higher rate of mutation than others.arrow_forwardHow might an evolutionary biologist explain why a species of salamander becomes blind after colonizing a cave? Group of answer choices Members of the ancestral population that colonized the cave differed in their ability to see. If maintaining the ability to see in the cave was a waste of energy, blind salamanders might actually have more offspring than those who could see. It is possible that in the cave there is a source of pollution that increases the mutation rate for a gene that makes salamanders blind. Over time, due to exposure to this chemical, the membersof the population lose their sight. There is no way to explain this in terms of natural selection. The members of this salamander species no longer needed to use their eyes. Over time, due to lack of use, they lost the ability to see.arrow_forward1.Chimpanzees and humans appear very much alike because of? * a. common adaptations to similar environmental conditions evolved in both b. They shared common traits c. They shared analogous traits d. Genetically shared 50% of their genes. 2. Circle the letter of each sentence that is true about evolutionary relationship of organisms? * a. DNA evidence shows that the giant pandas are more closely related to raccoons than bears. b. Scientist infer that the species with similar body structure and development patterns inherited many of the same genes from acommon ancestor.a c. Scientist never have to change their hypotheses about species relationships. d. Scientist can compare protein structure to determine how closely two species are related .arrow_forward
- Briefly discuss the differences in how a selectionist (one that believes that Natural Selection is a strong evolutionary force) and a neutralist (one that believes that genetic drift is a strong evolutionary force) views the following: molecular clock, evolution of coding sequences, evolution of "pseudogenes".arrow_forwardTracing the evolutionary thought was not easy because of many scientists who were interested in this study. arrange the events in order using numbers 1-10. ___The chromosomal theory of heredity was established. ___Chimpanzees are more closely related to humans than to gorillas was demonstrated. ___Neanderthal skull and bones are found in Neander valley in Germany. ___Modern hierarchical classification system was developed. ___Mendelian laws of inheritance and the hypothesis that genes are located on chromosomes was confirmed. ___The human genome is sequenced and assembled. ___Systematics and the Origin of Species in which he presents his influential ‘biological species concept’ was published. ___It was shown that humans share nearly 99% of their DNA with chimpanzees. ___Radiometric dating techniques are developed during this decade. ___The Descent of Man, and Selection in Relation to Sex was published.arrow_forwardExample 3The Basque people, who have a distinct language, live on the coastal border of France and Spain. The 700,000 modern Basques had long been thought to descend from hunter-gatherers who lived in the area about 7,500 years ago, before the first farmers arrived. DNA told a different story. Researchers compared the genome sequences of bones from eight Basque farmers who had lived in a cave in northern Spain from 5,500 to 3,500 years ago to genomes from other skeletons representing severalEuropean hunter-gatherers and early farming groups, as well as to modern Europeans. While the ancient farmers had genomes representing many groups, including those of hunter-gatherers, the Basques indeed have a unique genome – but one that descends from the earliest farmers, not from hunter-gatherers. Apparently, their uniqueness today is due to their self-imposed isolation as the rest of Europe interbred. Source: Lewis, Ricki. Human Genetics Concepts and Applications (2018). Twelfth edition.…arrow_forward
- Why might some light-skinned populations, such as the Japanese, be missing the F374 allele for lighter skin pigmentation? (Hint: Consider the various forces of evolution that may be at play.)arrow_forwardChimpanzees and humans appear very much alike because of? * a. common adaptations to similar environmental conditions evolved in both b. They shared common traits c. They shared analogous traits d. Genetically shared 50% of their genes. Circle the letter of each sentence that is true about evolutionary rel ationship of organisms? * a. DNA evidence shows that the giant pandas are more closely related to raccoons than bears. b. Scientist infer that the species with similar body structure and development patterns inherited many of the same genes from acommon ancestor.a c. Scientist never have to change their hypotheses about species relationships. d. Scientist can compare protein structure to determine how closely two species are related . A monophyletic group is a ________. *…arrow_forwardEVOLUTION LINK Write short paragraphs explaining each of the following statements: (a) Natural selection chooses from among the individuals in a population those most suited to current environmental conditions. It does not guarantee survival under future conditions. (b) Individuals do not evolve, but populations do. (c) The organisms that exist today do so because their ancestors had traits that allowed them and their offspring to thrive. (d) At the molecular level, evolution can take place by the replacement of one nucleotide by another. (e) Evolution is said to have occurred within a population when measurable genetic changes are detected.arrow_forward
- Biology (MindTap Course List)BiologyISBN:9781337392938Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. BergPublisher:Cengage Learning