LEAP 2025 Biology Practice Test

Which claim is supported by evidence from Graph 1? A. Snails with yellow shells live in all three habitats, but those with banding have a survival advantage in hedge habitats. B. Snails with yellow shells and banding are less able to survive in wood habitats. C. Snails with brown shells live in all three habitats, but they have a survival advantage in meadow habitats. D. Snails with brown shells and no banding are most often found in meadow habitats.

B. Snails with yellow shells and banding are less able to survive in wood habitats.

One reason that the number of deaths due to measles is significantly lower than the number of deaths due to HIV/AIDS is the introduction of ______. The large number of cases of tuberculosis despite an effective treatment strategy suggests that complete control of an infectious disease depends on educating patients about __________________.

One reason that the number of deaths due to measles is significantly lower than the number of deaths due to HIV/AIDS is the introduction of vaccines. The large number of cases of tuberculosis despite an effective treatment strategy suggests that complete control of an infectious disease depends on educating patients about proper use of antibiotics.

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 ______.

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.

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.

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.

Use Graph 2 and Figure 1 to answer the question. Part A Which statement best predicts how yellow-banded snails will be affected if the trends shown in Graph 2 continue? A. Yellow-banded snails will migrate from higher elevations to lower elevations. B. Yellow-banded snails will migrate from northern regions to southern regions. C. Yellow-banded snails will become more common in areas that have historically cooler temperatures. D. Yellow-banded snails will be found in a much wider range than the region in which they were historically found. Part B Which statement supports your prediction from Part A?​ A. Yellow-banded snails are able to live in all environments, but predation rates were historically higher in certain areas prior to climate change. B. Yellow-banded snails in cooler areas will become extinct because they are unable to adapt to changing conditions. C. Yellow-banded snails will move to areas where there are fewer migratory predators. D. Yellow-banded snails are better suited to live in warmer climates than snails with other-colored shells.

Part A C. Yellow-banded snails will become more common in areas that have historically cooler temperatures. Part B D. Yellow-banded snails are better suited to live in warmer climates than snails with other-colored shells.

Part A Which claim about changes in biodiversity in the San Joaquin Valley is supported by the information in Figure 1? A. Biodiversity has increased because of the expansion of agriculture. B. Biodiversity has increased because woodlands have been removed. C. Biodiversity has decreased because species have migrated out of the valley. D. Biodiversity has decreased because a variety of habitats have been reduced. Part B Which statement best explains why biodiversity is important for all life on Earth?​ A. Low biodiversity prevents the loss of species by increasing the types of organisms that can live in one area. B. High biodiversity tends to stabilize an ecosystem by reducing the rate at which species become extinct. C. High biodiversity changes an ecosystem by reducing the survival rate of all but the individuals best suited to an area. D. Low biodiversity results in stable ecosystems by increasing competition for resources among individuals.

Part A D. Biodiversity has decreased because a variety of habitats have been reduced. Part B B. High biodiversity tends to stabilize an ecosystem by reducing the rate at which species become extinct.

Drag each word or phrase into the correct box to identify whether or not each word or phrase represents a reason for the change in chimpanzee hands. mutations in chimpanzee DNA sexual reproduction crossbreeding differences in the ways chimpanzees differences in enhancer sequences A Reason for the Change in Chimpanzee Hands Not a Reason for the Change in Chimpanzee Hands

A Reason for the Change in Chimpanzee Hands mutations in chimpanzee DNA sexual reproduction differences in enhancer sequences Not a Reason for the Change in Chimpanzee Hands crossbreeding differences in the ways chimpanzees

Which statements explain the most likely cause of the difference between the hands of chimpanzees and those of gorillas? ​ Select the three correct answers. A. A single nucleotide base in the enhancer sequence changed, which caused an activator protein to bind to the enhancer sequence. B. Several individual chimpanzees all developed 0 the same mutation at the same time, which caused them to grip branches better. C. Chimpanzees used their hands for climbing more than gorillas did, so their DNA mutated to disable enhancers and caused their hands to develop differently from those of gorillas. D. The exchange of pieces of DNA between alleles during sexual reproduction caused new combinations of DNA to form. E. An individual had a genetic mutation that resulted in a hand structure with a selective advantage that was passed on to offspring. F. Mutations in the enhancer sequences in chimpanzees resulted in the production of new activator proteins.

A. A single nucleotide base in the enhancer sequence changed, which caused an activator protein to bind to the enhancer sequence. D. The exchange of pieces of DNA between alleles during sexual reproduction caused new combinations of DNA to form. E. An individual had a genetic mutation that resulted in a hand structure with a selective advantage that was passed on to offspring.

Use the information and your knowledge of science to answer the question. ​ During an investigation, two German shepherds with long hair were each bred with a German shepherd with short hair in a first-generation cross. The offspring from each first-generation cross were then bred to produce a second-generation cross. ​ Which questions could be answered using the results of this investigation? ​ Select the three correct answers. A. Is hair length in German shepherds a dominant or recessive trait? B. How often does the mutation for long hair randomly occur in German shepherds? C. How does the protein made by the gene for hair length differ among German shepherds? D. Is long hair in German shepherds an inherited trait? E. What percentage of offspring in the second generation of German shepherds are homozygous for the recessive hair-length trait?

A. Is hair length in German shepherds a dominant or recessive trait? D. Is long hair in German shepherds an inherited trait? E. What percentage of offspring in the second generation of German shepherds are homozygous for the recessive hair-length trait?

Rock pocket mice are a type of small rodent found in the southwestern United States. These mice can have dark or light fur. Differences in the fur color of rock pocket mice are the result of a recessive mutation in a single gene, known as agouti. The agouti mutation causes dark fur to be striped with a band of reddish brown, resulting in lighter fur color. Scientists have noticed changes over time in fur coloration of populations of rock pocket mice living in locations with light, sandy-colored rock compared to those living in locations with black rock. The graph shows how populations of rock pocket mice are expected to change over the course of one hundred years after moving to each location.​​ ​Which explanations support the patterns seen in the graph?​ Select the three correct answers. A. Mice that have dark fur and live on sandy-colored rock are easy prey for hungry hawks and owls. B. Mice with dark fur cannot survive on black rock because the temperature is too hot. C. Mice with dark fur can more easily hide on sandy-colored rock. D. Mice born with the agouti trait are more likely to survive to breed and reproduce on sandy-colored rock. E. Mice with light fur are less likely to survive on black rock than on sandy-colored rock. F. In locations with black rock, the agouti mutation quickly becomes extinct.

A. Mice that have dark fur and live on sandy-colored rock are easy prey for hungry hawks and owls. D. Mice born with the agouti trait are more likely to survive to breed and reproduce on sandy-colored rock. E. Mice with light fur are less likely to survive on black rock than on sandy-colored rock.

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.

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 the information and your knowledge of science to answer the question. ​ Body systems often work together to achieve a goal. For example, several body systems are involved when the body engages in what is known as the "fight-or-flight" response to possible danger. The diagram shows the body systems involved in this response. ​ ​ Which statements describe how systems interact to produce the fight-or-flight response? ​ Select the two correct answers. A. The digestive system creates hormones that are sent to the muscular system, resulting in increased blood flow to muscles. B. The endocrine system floods the circulatory system with hormones that affect several other body systems. C. The muscular system sends receptors to the circulatory system to increase blood pressure and heart rate. D. The digestive system interacts with the excretory system, supplying hormones to slow the production of urine. E. The endocrine system supplies the lungs with insulin, allowing increased absorption of oxygen. F. The circulatory system experiences a change in blood flow, which allows the muscular system to obtain additional glucose.

B. The endocrine system floods the circulatory system with hormones that affect several other body systems. F. The circulatory system experiences a change in blood flow, which allows the muscular system to obtain additional glucose.

Scientists discovered a new pathogen that causes disease in humans. The pathogen measures 50 to 60 nanometers (nm) in length and is spread by the bite of a mosquito. After incubating for three to six days, it causes a variety of symptoms in affected patients, including fever, headache, muscle pain, and vomiting. The best treatment includes bed rest, fluids, and painkillers, if necessary. Antibiotics are not prescribed for this disease, but, in some cases, extra oxygen is given to help with breathing.​ To correctly identify the pathogen, scientists considered the characteristics of other diseases. The table shows some of this information.​ ​Which claim about the pathogen is supported by evidence from the table? A. The pathogen is most likely a virus because of its symptoms and its incubation time. B. The pathogen is most likely a virus because of its size and its treatment. C. The pathogen is most likely a bacterium because of its transmission method and the disease it caused. D. The pathogen is most likely a bacterium because of its symptoms and its incubation time.

B. The pathogen is most likely a virus because of its size and its treatment.

Use the information in Table 1 and Figure 1 to answer the question. ​ Which change is most responsible for the decline of the kit fox population? A. an increase in predator habitat due to reduced competition B. a reduction in carrying capacity due to habitat loss C. a reduction in carrying capacity due to decreased temperatures D. an increase in insect populations due to agriculture

B. a reduction in carrying capacity due to habitat loss

Use the information in Table 1 and Figure 1 to answer the question.​Which change is most responsible for the decline of the kit fox population? A. an increase in predator habitat due to reduced competition B. a reduction in carrying capacity due to habitat loss C. a reduction in carrying capacity due to decreased temperatures D. an increase in insect populations due to agriculture

B. a reduction in carrying capacity due to habitat loss

Which change is most responsible for the decline of the kit fox population? A. an increase in predator habitat due to reduced competition B. a reduction in carrying capacity due to habitat loss C. a reduction in carrying capacity due to decreased temperatures D. an increase in insect populations due to agriculture

B. a reduction in carrying capacity due to habitat loss

Use the information and your knowledge of science to answer the question. ​ A scientist crosses morning glory plants of different flower colors to determine how flower color is passed on to offspring. The results of three crosses are shown in the table. ​​ ​The scientist crosses an offspring from cross X with an offspring from cross Z. What are the expected results of this cross? A. 100% of plants with red flowers B. 100% of plants with purple flowers C. 50% of plants with red flowers, 50% of plants with purple flowers D. 75% of plants with purple flowers, 25% of plants with red flowers

C. 50% of plants with red flowers, 50% of plants with purple flowers

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.

C. Changes in placodes over time allowed for the development of different structures.

Use your knowledge of science to answer the question. ​ ​Which statements describe steps in photosynthesis? ​ ​Select the three correct answers. A. Glucose is broken down into carbon dioxide and water. B. Energy is stored in the bonds of ATP. C. Light energy is absorbed by chlorophyll. D. Organic matter and oxygen combine to break molecules into smaller parts. E. Energy is used to convert carbon dioxide and water into sugar. F. Energy in the form of heat is used to absorb carbon dioxide. G. Water is broken apart to produce oxygen.

C. Light energy is absorbed by chlorophyll. E. Energy is used to convert carbon dioxide and water into sugar. G. Water is broken apart to produce oxygen.

Which human intervention would most likely protect and maintain kit fox populations? A. Move kit foxes to areas with large populations of similar mammals. B. Move kit foxes to sparsely populated mountainous regions. C. Protect grasslands and prairies from development. D. Introduce a species that could be a new kit fox food source.

C. Protect grasslands and prairies from development.

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.

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 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.

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.

Use the information and your knowledge of science to answer the question.​The model shows the process of photosynthesis.​​ Drag each phrase into the appropriate column of the table to show what this model of photosynthesis can and cannot be used to explain. how energy is stored within carbohydrates how glucose is built from smaller molecules how oxygen gas is released from water molecules how carbon dioxide is split how sugars are broken down to release energy how the Sun's energy is stored within carbon dioxide molecules Can Be Explained Using This Model of Photosynthesis Cannot Be Explained Using This Model of Photosynthesis

Can Be Explained Using This Model of Photosynthesis how energy is stored within carbohydrates how glucose is built from smaller molecules how oxygen gas is released from water molecules how carbon dioxide is split Cannot Be Explained Using This Model of Photosynthesis how sugars are broken down to release energy how the Sun's energy is stored within carbon dioxide molecules

Use the information and your knowledge of science to answer the question.​ Drag each statement into the correct box to identify the causes and effects of Huntington's disease within a population. Cause Effect Dutch settlers in South Africa carried the gene for Huntington's disease. Dutch settlers remained in small communities within South Africa. Only 766 male immigrants are the ancestors of 56 million South Africans. People of Dutch ancestry in South Africa have an unusually high frequency of the allele that causes Huntington's disease.

Cause Dutch settlers in South Africa carried the gene for Huntington's disease. Dutch settlers remained in small communities within South Africa. Effect Only 766 male immigrants are the ancestors of 56 million South Africans. People of Dutch ancestry in South Africa have an unusually high frequency of the allele that causes Huntington's disease.

Use Graph 1, Figure 1, and the information about banded snails to answer the question. ​ Drag the correct statement into each box to show an effect that each cause is likely to have on a snail population with a high degree of genetic diversity.​ Not all statements will be used. DRAG & DROP THE ANSWER Choices: Only snails with a lighter shell color and banding are able to survive in the new environment. Dark-colored banded snails become more common than yellow-colored banded snails. Snails with a darker shell color are less likely to survive and reproduce to pass traits on to offspring. Snails of any color with the most banding survive better than snails with any color and no banding. Cause: Regions begin experiencing cooler than average winter climates. A new species of predator is able to detect darker colors better than song thrushes can. Warmer temperatures cause wood environments to change into hedge environments.

Cause: Regions begin experiencing cooler than average winter climates. Effect: Dark-colored banded snails become more common than yellow-colored banded snails. Cause: A new species of predator is able to detect darker colors better than song thrushes can. Effect: Snails with a darker shell color are less likely to survive and reproduce to pass traits on to offspring. Cause: Warmer temperatures cause wood environments to change into hedge environments. Effect: Snails of any color with the most banding survive better than snails with any color and no banding.

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.

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.

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.

D. The same sequences are found in the genetic information of theropods and birds.

Chimpanzees within a population have a range of different hand shapes and sizes, but all chimpanzees carry the mutant enhancer protein that causes their hands to differ from those of gorillas. ​ Select the correct answer from each drop-down menu to support a claim about how the mutant enhancer protein became common within the chimpanzee population. Evidence suggests that chimpanzees and gorillas descended from a common ancestor that produced a ____ enhancer protein.​ At one point, ____ developed a mutation in the ____ that affected hand shape. This trait was passed on to offspring over man generations, and those individuals ____ the trait were more successful than other individuals. This resulted in the mutant enhancer protein becoming common among all chimpanzees.

Evidence suggests that chimpanzees and gorillas descended from a common ancestor that produced a normal enhancer protein.​ At one point, an individual chimpanzee developed a mutation in the DNA that affected hand shape. This trait was passed on to offspring over man generations, and those individuals with the trait were more successful than other individuals. This resulted in the mutant enhancer protein becoming common among all chimpanzees.

Use the information and your knowledge of science to answer the question. ​ Like all fruit, pears continue to undergo cellular respiration after they are harvested. As pears ripen, they begin respiration, and carbohydrates in the fruit are converted to other forms. If enough time goes by, the fruit may begin to rot. Growers want to keep the pears unripe for as long as possible, and ripen the fruit just before sending them to the supermarket. For this reason, growers have investigated storing pears under different conditions. The graph shows the results of one investigation. ​ ​ Select the correct answer from each drop-down menu to complete the sentences related to cellular respiration in pears. ​ For long-term storage of pears, the oxygen concentration should be _____ and the temperature should be _____. This will result in the _____ amount of energy being used by the pears.

For long-term storage of pears, the oxygen concentration should be 5% and the temperature should be 7°C. This will result in the least amount of energy being used by the pears.

Vitamin D is a molecule that assists chemical reactions within a cell. Human skin cells produce vitamin D when they are exposed to ultraviolet radiation from the Sun. The model shows how the body metabolizes (alters and uses) vitamin D.​ ​Select the correct answer from each drop-down menu to show what the model can be used to explain about vitamin D metabolism.​ In order to make vitamin D into a usable form, it must first be transported from the skin to different​ _____. The model shows that the interaction of _____ is necessary to accomplish specific functions within the body.

In order to make vitamin D into a usable form, it must first be transported from the skin to different​ organs within each system. The model shows that the interaction of different organ systems is necessary to accomplish specific functions within the body.

Sheephead are a species of large fish that are a key predator in a kelp forest ecosystem. Scientists have learned that approximately 60 percent of their diet consists of crabs, 9 percent consists of sea urchins, and 6 percent consists of bivalves (clams, mussels, oysters). Scientists examined how removing sheephead from a community affects the sea urchin population. The graph shows the results of this investigation, which began in October 1980.​ Part A Which claims are supported by evidence from the graph?​ ​Select the two correct answers. A. A large sheephead population will cause the sea urchin population to decrease. B. As the sea urchin population decreases, the population of sheephead decreases due to starvation. C. The sea urchin population has a limiting effect on the sheephead population. D. The size of the sheephead population has a direct effect on the size of the sea urchin population. E. Sea urchin survival depends on a stable sheephead population. Part B Which statement uses information from the graph that supports the answer to Part A?​ A. The sea urchin population with sheephead present was higher in April 1982 than it was in June 1981. B. The sea urchin population with sheephead present decreased between 1980 and 1982. C. The sea urchin populations with sheephead present and with sheephead absent were the same in November 1980. D. The sea urchin population with sheephead absent was smaller in 1982 than it was in 1980.

Part A A. A large sheephead population will cause the sea ur chin population to decrease. D. The size of the sheephead population has a direct effect on the size of the sea urchin population. Part B B. The sea urchin population with sheephead present decreased between 1980 and 1982.

A saline solution (a type of salt water) can be added to a patient's bloodstream during medical procedures. However, if the concentration of salt is too high, blood cells may become damaged. ​ ​A student decides to perform an investigation to test this claim. ​ Part A Which investigations are most appropriate to help the student test the claim? ​ ​Select the three correct answers. A. Use a microscope to examine changes in leaf cells placed in solutions of 1% or 10% salt. B. Measure the mass of carrot sticks before and after being placed in solutions of either salt water or fresh water. C. Examine how quickly colored salt water moves into potato cubes that are 5 mm or 10 mm in length. D. Monitor how quickly celery stalks of different lengths take in colored water. E. Compare the firmness of spinach leaves placed in a salt solution overnight with those placed in fresh water overnight. Part B Which statements explain the answers to Part A?​ Select all that apply. ​ A. Cells placed in fresh water may burst. B. Cells placed in fresh water will shrink in size. C. Tissues placed in salt water will weigh more than those placed in fresh water. D. Cells placed in salt solutions will become stiff. E. Solutions with a high salt concentration will diffuse faster than solutions with a low salt concentration. F. Water will move out of cells that are placed in a solution with a high salt concentration.

Part A A. Use a microscope to examine changes in leaf cells placed in solutions of 1% or 10% salt. B. Measure the mass of carrot sticks before and after being placed in solutions of either salt water or fresh water. E. Compare the firmness of spinach leaves placed in a salt solution overnight with those placed in fresh water overnight. Part B A. Cells placed in fresh water may burst. F. Water will move out of cells that are placed in a solution with a high salt concentration.

Use the information in Figure 1 to answer the questions. Part A Which claim about changes in biodiversity in the San Joaquin Valley is supported by the information in Figure 1? A. Biodiversity has increased because of the expansion of agriculture. B. Biodiversity has increased because woodlands have been removed. C. Biodiversity has decreased because species have migrated out of the valley. D. Biodiversity has decreased because a variety of habitats have been reduced. Part B Which statement best explains why biodiversity is important for all life on Earth?​ A. Low biodiversity prevents the loss of species by increasing the types of organisms that can live in one area. B. High biodiversity tends to stabilize an ecosystem by reducing the rate at which species become extinct. C. High biodiversity changes an ecosystem by reducing the survival rate of all but the individuals best suited to an area. D. Low biodiversity results in stable ecosystems by increasing competition for resources among individuals.

Part A D. Biodiversity has decreased because a variety of habitats have been reduced. Part B B. High biodiversity tends to stabilize an ecosystem by reducing the rate at which species become extinct.

Part A The data for 1945 in Table 2 represent the typical relationship between environmental factors and the growth pattern for trees in the Dolomite mountain range. ​ Select the correct answer from each drop-down menu to complete the claim about which conditions are ideal for producing tonewood trees. ​ Tonewood trees are most likely to be produced as a result of ________ temperatures and ______ precipitation. Part B Which statements are evidence that supports the answer to Part A? Select all that apply.​ A. In years with average temperatures, the growth rates of the trees at both sites were average. B. In years with lower-than-average temperatures, the rate of cellular respiration fluctuated randomly at site 1. C. In years with higher-than-average temperatures, the rate of cellular respiration decreased at site 1. D. In the year with lower-than-average precipitation, the rate of cellular respiration in trees at both sites was lower than average. E. In the year with above-average temperatures and average precipitation, the rate of growth at site 2 decreased. F. In the year with average precipitation, the growth rates for trees at site 1 and site 2 were the same.

Part A Tonewood trees are most likely to be produced as a result of higher-than-average temperatures and lower-than-average precipitation. Part B D. In the year with lower-than-average precipitation, the rate of cellular respiration in trees at both sites was lower than average. E. In the year with above-average temperatures and average precipitation, the rate of growth at site 2 decreased.

Temperature regulation in humans is controlled by feedback mechanisms. If body temperature decreases below the optimal temperature, the central nervous system causes muscles in the skin to contract. This pulls each hair into a vertical position and causes parts of the skin to raise into small bumps called goosebumps. This response helps reduce the amount of blood that is exposed to the environment.​ A student wants to investigate the feedback mechanism that causes goosebumps.​​ Drag the correct statement into each box to show the most appropriate order of the steps a student should take in this investigation.​​ Not all statements will be used. DRAG & DROP THE ANSWER Ask the participant whether or not his or her Observe the hand in water for goosebumps. Observe the hand in water for goosebumps. Have a participant place one hand into a Drip each water. Prepare one bowl of hot water, one bowl of room-temperature water, and one bowl of cold water. Drip each watersample on the back of the participant's neck. Record observation data.

Step 1 Prepare one bowl of hot water, one bowl of room-temperature water, and one bowl of cold water. Step 2 Drip each watersample on the back of the participant's neck. Step 3 Observe the skin on the arms and legs of the participant. Step 4 Record observation data.

Scientists studying San Joaquin kit foxes have proposed the three strategies shown in an effort to increase the kit fox population. ​Strategy 1: Work with landowners to create artificial dens that prevent coyotes and bobcats from entering. Strategy 2: Place tracking devices on lizards and rodents to understand how the kit fox's prey use the territory. Strategy 3: Restore a portion of agricultural land back to its original saltbush habitat. Identify which strategy is likely to result in the greatest increase in the San Joaquin kit fox population. Explain why the strategy you identified is more likely than the other two strategies to lead to the greatest increase in the kit fox population. Use evidence from the information about kit foxes to support your explanation.

Strategy one is to work with landowners to create artificial dens that prevent coyotes and bobcats from entering. I think this would be a great idea because one of the main reasons for the danger of the San Joaquin kit foxes is their predators are eating them. There's been an increase in coyotes.

Scientists have noted a difference in the concentration of atmospheric gases available to Norway spruce trees at site 1 and site 2. Use Table 1 and Figure 2 to describe the difference in atmospheric gases at each site. Explain how the flow of matter and energy differs in these two locations as a result of the concentration difference. Use evidence from any of the tables or figures to support your answer.

Table 1 shows that trees at site 2 grow faster and are at a lower elevation than trees at site 1. Faster growth means that the processes of photosynthesis and subsequent cellular respiration occur more quickly. Photosynthesis requires carbon dioxide, so trees at site 2 have a higher concentration of CO2 than the trees at site 1. As a result of a higher concentration of CO2, there is more energy and matter available to all other organisms in the food web at site 2 than at site 1.

Develop a model that can be used to explain the stages of growth and development that result in a salmon fry.

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.

As the climate in northern regions changes, the population of snails with darker-colored shells will likely​ ______ because they have _____ than snails with lighter-colored shells.

As the climate in northern regions changes, the population of snails with darker-colored shells will likely​ decrease because they have higher body temperatures than snails with lighter-colored shells.

In the Gulf of Mexico, seagrass meadows are nurseries for many young animals. Polychaetes are a type of invertebrate that lives on seagrass and provides food to many of the animals that live in the seagrass meadows.​ To study the effect of predators on different species of polychaetes, scientists divided four large fish tanks into two halves. Seagrasses containing different species of polychaetes were placed into both halves of all four fish tanks. A predator was placed into only one of the two halves in each of the four fish tanks. After a few days, the scientists counted the total number of polychaetes in each half of the tank.​ The results are shown in the graph.​ ​Next, the scientists counted the number of polychaete species in each half of the tank. The results are shown in the table.​​ ​Based on the information in the graph and the table, how has competition among predators affected species diversity in seagrass meadows in the Gulf of Mexico? A. Over time, pink shrimp have adapted to eat a wider variety of prey species compared to other predator species. B. Over time, blue crab have adapted to eat more of their diet in polychaetes compared to other predator species. C. Over time, the number of pink shrimp has decreased and the number of pinfish has decreased. D. Over time, the number of grass shrimp has decreased and the number of blue crab has increased.

A. Over time, pink shrimp have adapted to eat a wider variety of prey species compared to other predator species.

Use Figure 2 to answer the question. ​ The model shown in Figure 2 can best be used to explain the answer to which question? A. Why did some individuals develop the mutation that disrupts a working enhancer? B. When a working enhancer binds to a gene, does it affect the amount of protein that can be produced? C. What happens when an activator protein binds to the working enhancer in a strand of DNA? D. When a coding region of a gene becomes inactive, is the deactivation of the enhancer proteins the only cause?

C. What happens when an activator protein binds to the working enhancer in a strand of DNA?

Steelhead trout spend a portion of their lives at sea but return to streams and rivers to reproduce. As dams were built on rivers, it became more difficult for steelhead trout to travel upriver, and populations decreased. However, more recently, the removal of dams has caused populations of steelhead trout to increase again. Scientists have observed changes to the populations of steelhead trout since the dams were removed. The figure shows changes noted at one location.​​Which statement best explains the change in the male steelhead trout population? A. Shorter males produce more sex cells than longer males, resulting in the fertilization of more eggs. B. Longer males use more energy for growth than shorter males, resulting in the production of fewer sex cells. C. Shorter males travel faster upriver than longer males and begin breeding with females earlier. D. Longer males are able to outcompete shorter males for access to females.

D. Longer males are able to outcompete shorter males for access to females.

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.

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.

As you respond to Part A, Part B, and Part C, follow the directions below. ​ ​Address all of the instructions in each prompt. Use the evidence from the information provided and your own knowledge of science to support your responses. ​Part A Based on the information in Graph 1, explain the relationships between shell color, presence of banding, and habitat. Use the evidence from the graph to support your answer. Part B The characteristics of two snail populations are shown. ​ ​Population 1: high degree of genetic variation among snails living in a wood environment at higher elevations Population 2: all snails have the same traits specialized for a hedge environment that is found in warmer locations ​Explain how each snail population will likely be affected if the trend shown in Graph 2 continues. Use evidence from Graph 1, Graph 2, and Figure 1 to support your explanation. ​ Part C Describe the snail color that will offer the greatest selective advantage if the trends shown in Graph 2 continue. Use evidence from the information on banded snails to support your claim.​

Part A Shell color, banding and habitat all correlate when determining the environments that each snail is best suited for. For example, Graph 1 shows a cluster of wooded area where snails are brown and have little to no banding. In opposition, there is a large amount of hedge area where snails are yellow and have a higher percentage of banding. And meadow areas are pretty spread out among the graph, showing that snails of either color with any type of banding are able to survive in that area. From this, we can gather that the shell color and presence of banding determine where the snails habitats may be. Wood snails will have darker shell colors and little to no banding, while hedge snails will have lighter shell colors and may have lots of banding. This is due to the camouflage that is necessary in each environment and can protect each snail from their predators. Part B Population 1 will probably survive the climate change because they have high genetic diversity, increasing the chances that some individuals will have traits that are adapted to the new environment. Population 2 is at a greater risk of extinction because their bodies will continue to warm with the changes to the environment. Part C The yellow snail color with banding will offer the greatest selective advantage if the trends shown in Graph 2 continue. As stated in the text, "...snails with lighter-colored shells have a lower body temperature than those with darker-colored shells." Lower-body temperatures entail that the organism can endure higher heat and must live in an overall warmer environment. Also, the text state, "Snails with darker-colored shells tend to be found living farther north than those with lighter-colored shells." Therefore, if the trend in Graph 2 continue, lighter-colored snails, in this case, yellow snails, would offer the greatest selective advantage, because they can withstand higher temperatures naturally because they can handle this overall warming in climate.