LEAP 2025 Biology Practice Test

Which claim is supported by the information in Graph 1 and Graph 2? A. The mass of the eggs and the number of eggs produced by sockeye salmon are independent of the females mass. B. The mass of the eggs produced by sockeye salmon depends on the female's average age at reproduction, but the number of eggs does not. C. The number of eggs and the mass of the eggs produced by sockeye salmon depend on the amount of matter stored by the female. D. The number of eggs produced by sockeye salmon decreases with female body length, but the mass of the eggs does not. - ANS C. The number of eggs and the mass of the eggs produced by sockeye salmon depend on the amount of matter stored by the female. Develop a model that can be used to explain the stages of growth and development that result in a salmon fry. - ANS 1. Sperm fertilizes egg. 2. Genetic material is evenly divided. 3. Embryo changes from two to four cells. 4. Cells differentiate. 5. Specialized tissues and organs are produced. Chum salmon fry average 3.8 cm in length, compared to 3 cm for pink salmon fry and 10 cm for coho salmon fry. Based on the information in Graph 3, chum salmon fry are likely to eat prey that is ______ prey eaten by the pink salmon fry and ______ prey eaten by the coho salmon fry. This is because as a salmon's size increases, its matter intake needs ______. - ANS Based on the information in Graph 3, chum salmon fry are likely to eat prey that is larger than prey eaten by the pink salmon fry and smaller than prey eaten by the coho salmon fry. This is because as a salmon's size increases, its matter intake needs increase. Which statement best explains how salmon obtain and use matter to support their biological functions? A. Salmon use complex, carbon-based molecules obtained directly from seawater and the atmosphere to produce other complex molecules, such as fats. B. Salmon use the carbon, hydrogen, and oxygen atoms obtained directly from seawater and the atmosphere to form sugars and proteins. C. Salmon break bonds in complex food molecules to release the carbon, oxygen, and hydrogen atoms needed for the formation of other molecules. D. Salmon break down carbon, hydrogen, and oxygen atoms obtained from food into smaller, energy-rich elements. - ANS C. Salmon break bonds in complex food molecules to release the carbon, oxygen, and hydrogen atoms needed for the formation of other molecules. Which claim is best supported by the information about scales and feathers? A. The presence or absence of placodes determines whether an organism develops feathers or scales. B. All vertebrates evolved directly from a common ancestor that had feathers. C. Changes in placodes over time allowed for the development of different structures. D. Placodes evolved directly from mutations that result in the growth of scales. - ANS C. Changes in placodes over time allowed for the development of different structures. Part A Which statement best explains what caused some theropods to develop feathers? A. A mutation in DNA affected the types of proteins produced by placodes. B. A protein in the placodes caused a mutation in the gene that produces feathers. C. A mutation in the placode gene caused placodes to produce different DNA. D. A mutation in DNA caused the placodes that control genes to grow feathers. Part B Which information is evidence that best supports the answer to Part A?​ A. The DNA of modern-day vertebrates codes for the proteins in placodes. B. All vertebrate embryos have the same genetic mutations in their placode DNA. C. Placodes in all modern-day embryos contain the same number of mutations. D. A single placode can spontaneously develop into any type of body covering. - ANS Part A A. A mutation in DNA affected the types of proteins produced by placodes. Part B A. The DNA of modern-day vertebrates codes for the proteins in placodes. Which evidence best supports the claim that birds evolved from dinosaurs? A. Placodes are found in the embryos of both theropods and birds. B. Theropods and birds both have genetic sequences that code for proteins. C. Theropods and birds have similar structures with similar functions. D. The same sequences are found in the genetic information of theropods and birds. - ANS D. The same sequences are found in the genetic information of theropods and birds. Mammals did not descend directly from dinosaurs, but mammals embryos have placodes, as show in Figure 3. ​ ​Use the information about scales and feathers to explain why mammal embryos and dinosaur embryos each have placodes. Identify the information that can be used as evidence to support your explanation, and then explain why this information can be used as evidence. - ANS Mammals and dinosaurs evolved from an ancestor that had placodes. Figure 2 shows that mammals and dinosaurs share a common ancestor, the amniotes. Since both mammals and dinosaurs have placodes, it is likely the ancestor of both types of organisms also had placodes and passed this characteristic down to the ancestors of mammals and the ancestors of dinosaurs. Which statement best explains the results shown in Table 1? A. Trees from site 1 grow less rapidly than trees from site 2 because the trees have slower rates of cellular respiration at site 1 than at site 2. B. Trees from site 1 grow less rapidly than trees from site 2 because the trees produce more oxygen at site 1 than at site 2. C. Trees from site 1 grow more rapidly than trees from site 2 because there are more hours of sunlight at site 1 than at site 2. D. Trees from site 2 grow more rapidly than trees from site 1 because there is less water available for trees at site 2 than at site 1. - ANS A. Trees from site 1 grow less rapidly than trees from site 2 because the trees have slower rates of cellular respiration at site 1 than at site 2. Use Table 1 and Figure 2 to answer the question. ​ Which claim about the transfer of energy in the tonewood ecosystem is best supported by data? A. At higher elevations, more energy is available to transfer from the trophic level occupied by the red deer than from the trophic level occupied by the Norway spruce. B. At lower elevations, more energy is available to transfer from the trophic level occupied by the Italian wolf than from the trophic level occupied by the European spruce bark beetle. C. More energy is available to transfer from the trophic level occupied by the Norway spruce at higher elevations than from the same trophic level at lower elevations. D. More energy is available to transfer from the trophic level occupied by the red deer at lower elevations than from the same trophic level at higher elevations. - ANS D. More energy is available to transfer from the trophic level occupied by the red deer at lower elevations than from the same trophic level at higher elevations.