24. The half-life of carbon-14 is about 5,730 years. A fossil that has 1/16 of the normal proportion of carbon-14 to carbon-12 should be about how many years old?
(A)2,800
(B)11,200
(C)16,800
(D)22,900

20.Darwin used the phrase"descent with modification'' to explain which of the foll (A) descent of all organisms from a single, ancient ancestor (B) the unity of life (C) the diversity of life (D) both the unity and diversity of life

21. Based on the tree below, which statement is correct? (A) Lizards and goats form a sister group. (B) Salamanders are a sister group to the group containing lizards, goats, and humans. (C) Salamanders are more closely related to lizards than to humans. (D) Goats and humans are the only sister group shown in this tree.

22. One population of a species has 25 individuals, all with genotype AA； a second population of this species has 40 individuals, all with genotype aa. Assume that these populations live far rt but in similar environmental conditions. Based on this information, the obs genetic variation most likely resulted from______. (A)genetic drift (B)gene flow (C)nonrandom mating (D)directional selection

23. Which of the following factors is the primary criterion for determining species boundaries when applying the biological species concept? (A)geographic isolation (B)niche differences (C)gene flow (D)morphological similarity

25. What is the function of reverse transcriptase in retroviruses? (A) It uses viral RNA as a template for DNA synthesis. (B) It converts host cell RNA into viral DNA. (C) It translates viral RNA into proteins. (D) It uses viral RNA as a template for making more viral RNA strands.

26. Some bacteria possess antibiotic resistance, as well as the ability to survive through adverse conditions. Where in this type of bacteria is the DNA located? (A) nucleoid, fimbriae, and plasmids (B)endospore, fimbriae, and plasmids (C)fimbriae, nucleoid, and endospore (D) plasmids, nucleoid, and endospore

27.After studying a particular species of protist, you suspect that it has obtained a cl secondary endosymbiosis. Which of the following information would confirm your hypothesis? (A)have nuclear and cyanobacterial genes (B)are exceptionally small (C) have three or four membranes (D) have only a single pigment

28.evidence do paleobotanists look for that indicates the movement of plants land? (A) waxy cuticle to decrease evaporation from leaves (B) loss of structures that produce spores (C) sporopollenin to inhibit evaporation from leaves (D) remnants of chloroplasts from photosynthesizing cells

29.nammals have skins and mucous membranes that are sensitive to secretions like poison oak. These secondary compounds are primarily adaptations that function in which of the following ways? (A)to favor pollination (B) to foster seed dispersal (C) to decrease competition (D) to inhibit herbivory

30.Fungi produce many compounds that humans use medicinally. Which of th statements best describes the evolution of these compounds in fungi? (A)Humans used artificial selection to develop fungi (B)That produced specific compounds. e presence of compounds in the fungi was accidentally produced and has r (C)The compounds probably provide a benefit to the fungi. (D) The compounds are produced as a result of sexual reproduction and recombination.