1. In which of the following ways do social insects benefit most from having several types or castes within the species? (A) Each colony is able to include a large number of individuals. (B) The secretions or odors produced by the protective caste are an effective defense. (C) The division of the species into castes ensures the survival of the fittest. (D) Large numbers of the worker caste can migrate to start new colonies. (E) The specialized structure of each caste permits division of labor and greater efficiency.

E. The specialized structure of each caste permits division of labor and greater efficiency.

2. The greatest diversity of structure and of methods of locomotion is exhibited in the individuals of (A) a class (B) a family (C) an order (D) a species (E) a phylum

E. a phylum

3. Of the following, which is an example of a mutualistic relationship? (A) The protozoan Trichonympha digesting wood in the gut of a termite (B) The sporozoan Plasmodium reproducing in human blood cells and liberating toxins into the human body (C) Two species of Paramecium deriving food from a common laboratory culture (D) Rabbits being eaten by foxes (E) Humans inadvertently providing food for cockroaches

A. The protozoan Trichonympha digesting wood in the gut of a termite

4. Evidence that multicellular green plants may have evolved from green algae is best supported by the fact that in both (A) the gametophyte generation is dominant (B) the sporophyte generation is dominant (C) chlorophylls a and b are photosynthetic pigments (D) xylem vessels are pitted and spiraled (E) male gametes are nonflagellated

C. chlorophylls a and b are photosynthetic pigments

5. All of the following statements concerning the light-capturing reactions of photosynthesis are true EXCEPT (A) An initial event is the excitation of electrons in chlorophyll by light energy. (B) The excited electrons are raised to a higher energy level. (C) If not captured, the excited electrons drop back to their initial energy levels. (D) If captured, some of the energy of the excited electrons is used to split carbon dioxide into carbon and oxygen. (E) Light is absorbed by pigments that are embedded in membranes.

D. If captured, some of the energy of the excited electrons is used to split carbon dioxide into carbon and oxygen.

6. Which of the following statements best explains the hypothesis that the development of sexual reproduction has resulted in acceleration of the rate of evolution? (A) Mutations are more likely to occur in spermatogenesis and oogenesis than in mitotically dividing cells. (B) Sexual reproduction results in more offspring than does asexual reproduction. (C) Those members of a species that are best adapted to their environment are most likely to be successful in sexual reproduction. (D) Mutations usually do not occur in the production of spores or in cells dividing by fission. (E) Sexual reproduction is more likely to result in genetic recombination than is asexual reproduction.

E. Sexual reproduction is more likely to result in genetic recombination than is asexual reproduction.

7. A frog skeletal muscle contracts in response to an electrical stimulus. Increase of the stimulus intensity by 50 percent will increase the strength of response nearly 50 percent. If the intensity is again increased 50 percent, the response will increase only about another 25 percent. Further increase in the stimulus intensity produces no further increase in response. The observations above are best explained by which of the following? (A) A muscle functions with an all-or-none mechanism. (B) Muscle-fiber sarcolemma is electrically resistant. (C) The fibers of a muscle do not all contract at the same rate. (D) The fibers of a muscle fatigue at varying rates. (E) The fibers of a muscle have varying thresholds for response.

E. The fibers of a muscle have varying thresholds for response.

8. Nitrogen-containing waste products are excreted as the result of the metabolism of which of the following? (A) Proteins (B) Fats (C) Simple sugars (D) Starch (E) Cellulose

A. Proteins

9. Deposits of coal in Greenland and the Antarctic indicate that (A) these regions once contained numerous mollusks that deposited carbohydrates in their shells (B) the Earth's crust in these regions contains vast amounts of limestone (C) these regions were once thickly vegetated (D) there is a rich store of dissolved carbon dioxide in the seas surrounding these regions (E) a geologic uplift of coral rock and ocean bed has recently occurred in these regions

C. these regions were once thickly vegetated

10. Thirst, loss of weight, and sugar in the urine result from the undersecretion of a hormone by which of the following glands? (A) Thyroid (B) Parathyroid (C) Pancreas (D) Adrenal (E) Thymus

C. Pancreas

11. Considering the role of mitochondria in cells, mitochondria would likely be most abundant in which of the following? (A) Mature red blood cells (B) Callous cells of the skin (C) Cells of the heart muscle (D) Epithelial cells of the cheek lining (E) Fat cells

C. Cells of the heart muscle

12. All of the following statements about enzymes are true EXCEPT (A) A single enzyme molecule can be used over and over again. (B) Most enzymes are highly specific with regard to the reactions they catalyze. (C) Some enzymes contain an essential nonprotein component. (D) Enzymes can function only within living cells. (E) Most enzymes are denatured by high temperatures.

D. Enzymes can function only within living cells.

13. Which of the following is critical in limiting the size to which an animal cell may grow? (A) The ratio of cell surface to cell volume (B) The abundance of mitochondria in the cytoplasm (C) The chemical composition of the cell membrane (D) The presence of an inelastic cell wall (E) The relative number of nucleoli

A. The ratio of cell surface to cell volume

14. Which of the following best describes the effect on heart action of the stimulation of the parasympathetic nerve fibers of the vagus nerve? (A) There is a decrease in the volume of blood pumped and an increase in the heartbeat rate. (B) There is an increase in the volume of blood pumped without a decrease in the heartbeat rate. (C) There is a prolonged acceleration in the heartbeat rate. (D) There is a decrease in the heartbeat rate. (E) There is an increase in the blood pressure.

D. There is a decrease in the heartbeat rate.

15. If poorly drained soils encourage the growth of bacteria that convert nitrate to nitrogen, the effect on higher plants will be to (A) increase lipid production (B) decrease protein production (C) increase carbohydrate production (D) produce unusually large fruits (E) stimulate chlorophyll production

B. decrease protein production

16. A patient is placed on a restricted diet of water, pure cooked starch, olive oil, adequate minerals, and vitamins. If a urinalysis several weeks later reveals the presence of relatively normal amounts of urea, the urea probably came from the (A) food eaten during the restricted diet (B) withdrawal of reserve urea stored in the liver (C) chemical combination of water, carbon dioxide, and free nitrogen (D) deamination of cellular proteins (E) urea synthesized by kidney tubule cells

D. deamination of cellular proteins

18. The codon for a particular amino acid is 5 prime C A U 3 prime. The D N A sequence that complements this codon is (A) 3 prime C A U 5 prime (B) 3 prime G T A 5 prime (C) 3 prime G T T 5 prime (D) 3 prime G U A 5 prime (E) 3 prime G U T 5 prime

B. 3 prime G T A 5 prime

19. Viral D N A would be most likely to contain genes that code for (A) regulatory hormones (B) viral-coat protein (C) viral-ribosome proteins (D) glycolytic enzymes (E) restriction enzymes

B. viral-coat protein

20. Which of the following statements about imprinting is NOT true? (A) The capacity for imprinting may be limited to a specific and brief period in the early life of the organism. (B) The behavior pattern associated with imprinting is the result of reward or punishment. (C) The behavior resulting from imprinting is difficult to reverse in later life. (D) A gosling imprinted by a moving wooden decoy may exhibit courting behavior to the decoy in later life. (E) Odors and sounds may serve as stimuli for imprinting.

B. The behavior pattern associated with imprinting is the result of reward or punishment.

22. Which of the following is the final electron acceptor in the mitochondrial electron transport system? (A) A D P plus P i (B) A T P (C) N A D or F A D (D) Pyruvate (E) O 2

E. O 2

23. In a eukaryotic cell, glycolysis occurs in which of the following parts of the cell? (A) Chloroplast (B) Cytosol (C) Nucleolus (D) Mitochondrion (E) Ribosome

B. Cytosol

24. The clotting process in blood is initiated by (A) erythrocytes (B) lymphocytes (C) hemoglobins (D) platelets (E) neutrophils

D. platelets

25. Which of the following statements best describes the movement of energy in an ecosystem? (A) 26. (A) Radiant energy is converted into chemical energy in plant photosynthesis and then released as heat energy during cellular respiration. (B) Energy cycles within an ecosystem. (C) Plants get energy from the nutrients in the soil. (D) The animals in an ecosystem absorb the radiant energy of the Sun and use it to make organic molecules such as proteins. (E) Some chemoautotrophic bacteria release energy that can then be used by soil animals to make food.

A. Radiant energy is converted into chemical energy in plant photosynthesis and then released as heat energy during cellular respiration.

26. Which of the following elements is correctly linked to its role in a living organism? 27. (A) Calcium .. component of proteins (B) Carbon .. component of lipids (C) Magnesium .. neuron action potential (D) Potassium .. component of A T P (E) Zinc .. component of carbohydrates

B. Carbon .. component of lipids

27. Mistletoe is attached to the branches of trees such as sweet gum, from which it obtains water and some nutrients. Due to this association, tree growth may be diminished. Which of the following terms describes the relationship between the two plants? 28. (A) Commensalism (B) Competition (C) Mutualism (D) Parasitism (E) Predation

D. Parasitism

28. A M P is which type of molecule? 29. (A) A nucleotide (B) A peptide (C) A phospholipid (D) A disaccharide (E) A tripeptide

A. A nucleotide

29. Which of the following is generally true about bacterial viruses? 30. (A) They infect animal cells only. (B) They have a protective capsid made of chitin. (C) They inject their nucleic acids into the cells that they infect. (D) They produce haploid gametes in meiosis. (E) They carry out glycolysis but not the Krebs (citric acid) cycle.

C. They inject their nucleic acids into the cells that they infect.

30. A typical photosynthetic eukaryotic cell contains which of the following? I. Ribosomes II. Chloroplasts III. Mitochondria (A) II only (B) I and II only (C) II and III only (D) I and III only (E) I, II, and III

E. I, II, and III

31. Which of the following pairs of organisms are most closely related? 32. (A) Mus bufo and Bufo americanus (B) Lynx lynx and Alces alces (C) Panthera leo and Felis concolor (D) Odocoileus virginianus and Colinus virginianus (E) Canis latrans and Canis lupus 33.

E. Canis latrans and Canis lupus 33.

32. Which of the following is an example of a testcross? (A) uppercase A uppercase A, cross, uppercase A lowercase a (B) uppercase A question mark, cross, uppercase A uppercase A (C) up p ercase A question mark, cross, uppercase A lowercase a (D) up p ercase A question mark, cross, lowercase a lowercase a (E) lowercase a lowercase a, cross, lowercase a lowercase a Directions: The following group of questions consists of five lettered headings followed by a list of numbered phrases. For each numbered phrase select the one heading that is most closely related to it. A heading may be used once, more than once, or not at all. Questions 34-36 refer to the following. Questions 33 through 35 refer to the following. (A) Fertilization (B) Meiosis (C) Mitosis (D) Pollination (E) Nondisjunction

D. Pollination

33. The process by which a zygote is formed 34. (A) Fertilization (B) Meiosis (C) Mitosis (D) Pollination (E) Nondisjunction

A. Fertilization

34. The process by which the nuclei of somatic (body) cells divide 35. (A) Fertilization (B) Meiosis (C) Mitosis (D) Pollination (E) Nondisjunction

C. Mitosis

35. The process by which haploid cells are formed from diploid cells (A) Fertilization (B) Meiosis (C) Mitosis (D) Pollination (E) Nondisjunction

B. Meiosis

36. Birds are most closely related to which class? 37. (A) Amphibians (B) Bony fish (C) Cartilaginous fish (D) Mammals (E) Reptiles

E. Reptiles

37. Which class includes animals that have a moist skin as the primary organ for gas exchange in the adults? 38. (A) Amphibians (B) Bony fish (C) Cartilaginous fish (D) Mammals (E) Reptiles

A. Amphibians

38. Which class includes whales? 39. (A) Amphibians (B) Bony fish (C) Cartilaginous fish (D) Mammals (E) Reptiles

D. Mammals

39. Members of which class produce milk for their young in specialized skin glands? 40. (A) Amphibians (B) Bony fish (C) Cartilaginous fish (D) Mammals (E) Reptiles

D. Mammals

40. Which class includes snakes? (A) Amphibians (B) Bony fish (C) Cartilaginous fish (D) Mammals (E) Reptiles

E. Reptiles

41. The most probable explanation for the relative masses of the first-and second-order consumers is that (A) each link in the food chain of an ecosystem has less available energy than the previous link has (B) only a small fraction of sunlight that reaches the Earth is transformed into chemical energy by photosynthesis (C) the total energy of the decomposers is greater than that of the rest of the organisms put together (D) seasonal fluctuations in weather limit the number of consumers (E) second-order consumers require more total energy than first-order consumers do

A. each link in the food chain of an ecosystem has less available energy than the previous link has

42. The energy incorporated into this ecosystem is most dependent on the 43. (A) photoperiod (B) total amount of photosynthesis (C) predator-prey relationships (D) length of the food chains (E) total amount of respiration 44.

B. total amount of photosynthesis

43. If the lake is assumed to be a typical ecosystem, the percent of radiant energy from the Sun reaching the lake that is trapped in photosynthesis is about (A) 100% (B) 10% (C) 1% (D) 0.1% (E) 0.01% Questions 45-47 Questions 44 through 46 Inheritance of certain characteristics of the fruit fly, Drosophila, is as indicated by the table below. Characteristic Dominant Recessive Body color . . . . . . . Gray Black Eye color . . . . . . . . Red White A female fruit fly had a gray body and white eyes. After being mated with a male fruit fly, she laid 112 eggs that developed into the following kinds of offspring. Number Body Eyes 28 Gray Red 29 Gray White 28 Black Red 27 Black White

C. 1%

44. With respect to body color, the male parent of the 112 offspring was most probably 45. (A) homozygous gray (B) heterozygous gray (C) homozygous black (D) heterozygous black (E) hemizygous gray 46.

C. homozygous black

45. Examination revealed that all of the 56 red-eyed offspring were females and all of the 56 white- eyed offspring were males. This observation indicates that (A) red and white eye colors segregate independently of sex (B) all of the red-eyed offspring inherited their eye color from their female parent (C) all of the red-eyed offspring were homozygous (D) the gene for eye color is linked to the gene for body color (E) the gene for red or for white eye color is carried on the X chromosome

E. the gene for red or for white eye color is carried on the X chromosome

46. In this experiment, the number of offspring that exhibit both recessive characters is 47. (A) 1 (B) 27 (C) 28 (D) 55 (E) 56

B. 27

47. Carbon dioxide is produced by which of the following? I. A mesophyll cell in a flowering plant during the night II. A muscle cell in a mammalian heart during contraction III. A yeast cell growing under anaerobic conditions (A) I only (B) II only (C) III only (D) I and II only (E) I, II, and III

E. I, II, and III

48. Which of the following is a function of A T P? (A) It creates energy. (B) It transports energy. (C) It is a building block of proteins. (D) It stores amino acids. (E) It gives the cells shape.

B. It transports energy.

49. Protein synthesis is the main function of which of the following structures? 50. (A) Nucleus (B) Ribosome (C) Chromosome (D) Mitochondrion (E) Vacuole Questions 51-55 Questions 50 through 54 Several different samples of D N A were digested with different restriction enzymes (endonucleases) and separated by gel electrophoresis, as shown below.

B. Ribosome

50. The terms Eco R 1 Hae 3 and Hin d 3 refer to which of the following? 51. (A) The voltage intensity used to prepare the electrophoresis medium (B) The restriction enzymes used (C) The organisms from which the original D N A sample was obtained (D) The types of buffers used to maintain a constant p H in the preparation as the sample was processed (E) The types of proteins encoded by each fragment

B. The restriction enzymes used

53. Restriction enzymes cut samples of D N Ainto fragments by first 54. (A) binding to specific sequences of nucleotides (B) oxidizing the D N A (C) heating the D N A to its denaturation point (D) breaking peptide bonds (E) unwinding the D N A

A. binding to specific sequences of nucleotides

55. Which of the following best explains why a pictorial presentation of the biomass at each trophic level of an ecosystem is a pyramid? 56. (A) The loss of iron from an ecosystem (B) The amount of energy passed from one trophic level to the next (C) The number of predators in the ecosystem (D) The chemical compounds in an ecosystem are recycled (E) The average size of the individuals in each species INPUT CO2 3-Phosphoglycerate Rubisco ATP ADP Ribulose bisphosphate (RuBP) ADP ATP 1, 3-Bisphosphoglycerate NADPH NADP+ (G3P) P i Glyceraldehyde 3-phosphate (G3P) OUTPUT (G3P) Other organic compounds

B. The amount of energy passed from one trophic level to the next

57. A diet with insufficient iodine will most likely lead to which of the following symptoms in an individual? 58. (A) Bleeding gums (B) Decreased metabolic rate (C) Increased body temperature (D) Increased respiratory rate (E) Weight loss 59.

B. Decreased metabolic rate

58. Which of the following structures is correctly paired with its function? (A) Alveolus . . locomotion (B) Cilium . . impulse transmission (C) Sarcomere . . nutrient uptake (D) Neuron . . gas exchange (E) Nephron . . filtration

E. Nephron . . filtration

59. Based on the genetic-code table, which of the following substitutions is synonymous? (A) AGU to AGA (B) GUU to GCU (C) UUG to CUG (D) UGA to GGA (E) CAA to CCA

C. UUG to CUG

60. Excess sewage can lead to the death of aquatic animals in a lake because sewage pollution promotes 61. (A) mineral starvation (B) erosion (C) thermal stratification (D) oxygen depletion (E) a temperature decrease

D. oxygen depletion

61. The aerobic cellular respiration of glucose is different from the simple burning of glucose in that the aerobic respiration of glucose 62. (A) releases no heat (B) requires no oxygen (C) releases more energy (D) releases hydrocarbons (E) occurs at a lower temperature 63.

E. occurs at a lower temperature 63.

62. A given trait occurs in two alternative types, uppercase M and lowercase m, in a population at Hardy-Weinberg equilibrium. If 49 percent of the population has only type uppercase M alleles, what percentage of the population is expected to be heterozygous for the trait? (A) 9% (B) 14% (C) 21% (D) 42% (E) 51%

D. 42%

63. The forelimbs of horses and frogs are considered to be homologous structures. The best evidence for this homology is that the forelimbs have 64. (A) a similar appearance in both species (B) a similar function in both species (C) a common embryological origin (D) the same chemical composition (E) the same number of bones

C. a common embryological origin

64. Which of the following types of plant cells is dead at functional maturity? 65. (A) Phloem companion cell (B) Xylem vessel element (C) Root endodermal cell (D) Stem cortex cell (E) Mesophyll cell

B. Xylem vessel element

65. In a particular plant species, the allele for tall plants is dominant and the allele for dwarfing is recessive. Which of the following is the expected phenotypic ratio of the offspring from a cross between a heterozygous plant and a dwarf plant? 66. (A) 1 tall plant to 3 dwarf plants (B) 1 tall plant to 9 dwarf plants (C) 1 tall plant to 1 dwarf plant (D) 3 tall plants to 1 dwarf plant (E) 9 tall plants to 3 dwarf plants

C. 1 tall plant to 1 dwarf plant

66. Which of the following best describes the decomposers in an ecological community? 67. (A) They are the top predators. (B) They do not occur in early successional stages. (C) They are the main contributors to the gross primary productivity. (D) They fix carbon for plant respiration. (E) They are heterotrophic.

E. They are heterotrophic.

67. The nearly universal nature of the genetic code supports the view that 68. (A) all living organisms on Earth share a common ancestor (B) nucleic acids were the first living things (C) proteins are of secondary importance to living systems (D) the protein composition of all living organisms is the same (E) there is redundancy in the genetic code Questions 69-70 Questions 68 and 69 The pedigree below shows the occurrence of a rare, sex-linked genetic condition in a family. Shaded symbols indicate the presence of the condition. Circles indicate females, and squares indicate males. I II III IV V 69.

A. all living organisms on Earth share a common ancestor

70. A katydid is an insect. Its leaf-like appearance is an example of 71. (A) cryptic coloration (B) aposematic coloration (C) Müllerian mimicry (D) agonistic behavior (E) Batesian mimicry 72.

A. cryptic coloration

71. A population of mice in Hardy-Weinberg equilibrium will exhibit which of the following conditions? (A) Random mating (B) Small population size (C) High mutation rate (D) Immigration (E) Sexual selection

A. Random mating

72. Which of the following biomes typically has the greatest annual precipitation? 73. (A) Temperate deciduous forest (B) Taiga (C) Savanna (D) Tropical rain forest (E) Prairie

D. Tropical rain forest

73. Which part of a flower develops into fruit? 74. (A) Sepal (B) Stigma (C) Anther (D) Ovary (E) Filament

D. Ovary

74. In a particular mammal, the egg has a haploid number of 8. How many chromosomes are in the somatic cells of that organism? (A) 2 (B) 4 (C) 8 (D) 16 (E) 32

D. 16

75. A new organism is found with the following characteristics. • A terrestrial lifestyle • A segmented exoskeleton • Wings The new organism is most likely a member of which of the following phyla? (A) Cnidaria (B) Porifera (C) Chordata (D) Arthropoda (E) Echinodermata

D. Arthropoda

76. Plants that live in the tundra are likely to have which of the following adaptations? 77. (A) Tall, single shoots (B) Broad, light-colored leaves (C) Cones that are fire adapted (D) An association with epiphytes (E) Shallow root systems

E. Shallow root systems

77. When a protein is heated, which of the following will most likely be disrupted? 78. (A) The amino acid sequence (B) The tertiary structure (C) The carbon backbone (D) The carboxyl groups (E) The peptide bonds

B. The tertiary structure

78. In some horses, the coat is a mixture of red and white hairs, called roan. Roan horses have one white-haired parent and one red-haired parent. This exhibits which of the following inheritance patterns? 79. (A) X-linked recessive (B) Lateral transmission (C) Codominance (D) Hybrid vigor (E) Autosomal recessive

C. Codominance

79. A population of crayfish exhibits wide variation in body size, which is a heritable trait. A species of fish that preys on crayfish has been introduced to the population, but the fish can only eat small crayfish. Which of the following is a likely prediction about the population of crayfish in the presence of the predator? 80. (A) The crayfish will evolve new antipredator behaviors. (B) The crayfish diet will shift to avoid competition with the fish. (C) The population will have a smaller average body size owing to stabilizing selection. (D) The population will have a larger average body size owing to directional selection. (E) The population will experience disruptive selection, resulting in two distinct size classes of crayfish.

D. The population will have a larger average body size owing to directional selection.

80. All of the following substances are potentially major sources of energy for the human body EXCEPT 81. (A) starches (B) sugars (C) vitamins (D) proteins (E) fats

C. vitamins

81. Which of the following are producers in an aquatic food chain? 82. (A) Crustaceans (B) Algae (C) Insects (D) Fungi (E) Trout 83.

B. Algae

82. Which of the following gives the correct sequence of events in the synthesis of a protein molecule? (A) D N A, t R N A, formation of polypeptide, m R N A (B) Formation of polypeptide, t R N A, m R N A, D N A (C) t R N A, m R N A, D N A, formation of polypeptide (D) D N A, m R N A, t R N A, formation of polypeptide (E) m R N A, formation of polypeptide, D N A, t R N A 84.

D. D N A, m R N A, t R N A, formation of polypeptide

83. A species of malaria-carrying mosquito lives in a forest in which two species of monkeys, A and B, coexist. Species A is immune to malaria, but species B is not. The malaria-carrying mosquito is the chief food for a particular kind of bird in the forest. If all of these birds are eliminated suddenly, which of the following would be the immediate observable consequence? (A) Increased mortality in monkey species A (B) Increased mortality in monkey species B (C) Increased mortality in the malaria-carrying mosquitoes (D) Emergence of malaria-resistant strains in monkey species B (E) Emergence of malaria-sensitive strains in monkey species A

B. Increased mortality in monkey species B

84. Evolution in action is seen in the case of the English peppered moth (Biston betularia). The proportion of melanic forms in the population, once increasing in areas of heavy soot pollution, is now decreasing. The most probable explanation of this is which of the following? 85. (A) Differential predation fluctuates randomly. (B) The birds that ate the dark forms have been killed off by the pollution. (C) Mutation and back mutation rates have changed. (D) Selection pressure has been reversed because of environmental quality control. (E) Lepidopterists have collected a disproportionate number of melanic forms. Questions 86-89 Questions 85 through 88 The graph below shows the relative amounts of DNA present during the stages in the division cycle of mouse fibroblast cells.

D. Selection pressure has been reversed because of environmental quality control.

85. A mouse fibroblast cell divides approximately every 86. (A) 1 hour (B) 9 hours (C) 10 hours (D) 19 hours (E) 22 hours

E. 22 hours

86. D N A is synthesized during 87. (A) stage 1 (B) stage 2 (C) stage 3 (D) stage 4 (E) none of the stages above

B. stage 2

87. The daughter cells separate during 88. (A) stage 1 (B) stage 2 (C) stage 3 (D) stage 4 (E) none of the stages above 89.

D. stage 4

88. How does the amount of D N A present during stage 1 compare with the amount present during stage 3 ? (A) It is equal to that present during stage 3 . (B) It is half as much as that present during stage 3 . (C) It is twice as much as that present during stage 3 . (D) It is three times as much as that present during stage 3 . (E) It is four times as much as that present during stage 3 . Questions 89 and 90 The pedigree shows the occurrence of a genetic condition in a family. A shaded symbol indicates individuals with the condition. A dot indicates a carrier. Circles indicate females, and squares indicate males.

B. It is half as much as that present during stage 3 .

90. Individuals who are carriers for a genetic condition have (A) two copies of the allele causing the condition (B) a mild presentation of the condition (C) one recessive allele for the condition (D) a somatic mutation in the gene for the condition (E) an undiagnosed condition

C. one recessive allele for the condition

91. The American toad and the Fowler's toad are two different species that have overlapping geographic ranges. The breeding season of the American toad is from late winter to early spring, whereas the breeding season of the Fowler's toad is from late spring to early summer. The difference in breeding seasons most likely results in which of the following? (A) Interspecific competition for mates (B) Interspecific competition for nutrients (C) The production of fertile hybrids (D) Gene flow between the two species (E) The maintenance of species boundaries

E. The maintenance of species boundaries

92. In the life cycle of an angiosperm, microspores are formed in the (A) anther (B) carpel (C) nectary (D) calyx (E) tracheid

A. anther

93. Addison's disease is a disorder of the adrenal glands. Which of the following processes is most likely to be directly affected by the disease? (A) Calcium release (B) Ovulation (C) Glucose metabolism (D) Steroid production (E) Circadian rhythm Questions 94 and 96 refer to the life cycle below.

D. Steroid production

97. In a seed-bearing vascular plant, what does the pollen grain contribute to the plant life cycle? (A) It forms the seed. (B) It contains the male gametophyte. (C) It contains the male sporophyte. (D) It contains the female sporophyte. (E) It forms the ovary.

B. It contains the male gametophyte.

98. A researcher has discovered a new species of microscopic eukaryotic parasite. Which of the following means of gathering information would best clarify the species' evolutionary relationship to other species? (A) Analyzing karyotypes from several members of the new species (B) Analyzing the new species' morphological characteristics (C) Comparing the developmental stages of the new species with those of close relatives (D) Comparing gene sequences for each of several highly conserved genes (E) Comparing the host ranges of several closely related species of parasites

D. Comparing gene sequences for each of several highly conserved genes