LEAP 2025 Biology Practice Test
Questions with All Correct
Answers
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. - Answer-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.
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 o -
Answer-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.
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 - Answer-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
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? - Answer-C. What happens when an activator
protein binds to the working enhancer in a strand of DNA?
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. - Answer-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.
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 - Answer-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.
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.
Questions with All Correct
Answers
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. - Answer-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.
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 o -
Answer-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.
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 - Answer-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
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? - Answer-C. What happens when an activator
protein binds to the working enhancer in a strand of DNA?
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. - Answer-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.
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 - Answer-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.
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.
