Name: ____________________________________
PRACTICE KEYSTONE EXAM
The Keystone Exam is broken down into two modules. This mock exam has the same number of multiple choice questions (32 for each module) and constructed-response questions
(4 for each module) as seen on the real keystone exam.
These are the instructions for the two styles of questions you will see on the exam Below are the scoring guidelines used by processional scorers for the constructed-response questions:
BIOLOGY MODULE 1
MULTIPLE-CHOICE ITEMS
___ 1.
A.
B.
C.
D.
Which characteristic is shared by all prokaryotic and eukaryotic organisms?
the ability to reproduce asexually
the ability to make their own food
the need for a source of energy
the need for oxygen for respiration
Use the diagram below to answer question 2
___ 2.
A.
B.
C.
D.
Which characteristic of life is best shown by this diagram?
DNA is the genetic code in an organism.
AN organism is made of one or more cells.
An organism responds to changes in its environment.
Changes occur in an organism as it grows and develops.
___ 3.
Life functions are performed at many levels of biological organization. Which level or biological organization is the simplest level at which a structure can
support life functions?
A. cell
B. tissue
C. organelle
D. organ system
Use the illustrations below to answer question 4.
___ 4.
A.
B.
C.
D.
Which statement best explains why these cells have structural differences?
The cells have different functions.
The cells evolved in different organisms.
One of the cells develops into the other type of cell.
One of the cells is more primitive than the other cell.
___ 5.
The opening of the stomata allows water to evaporate from inside the leaf in a process known as transpiration. As this occurs, water molecules cling to one
another and pull water in a continuous stream up the stem of the plant from the roots to the leaves. Which property of water makes this movement possible?
A. cohesion
B. freezing point
C. high specific heat
D. temperature-dependent density
Use the illustration below to answer question 3.
___ 6.
A.
B.
C.
D.
Which of the following is a property of water that allows a water strider to walk on the surface of water?
solubility
cohesion
high specific heat
low freezing point
Use the picture below to answer question 7.
___ 7.
A.
B.
C.
D.
The picture shows water droplets hanging on the tips of pine needles. How do the physical properties of water result in the image shown?
Cohesion allows droplets to form, and adhesion keeps the droplets on the needles.
Adhesion allows droplets to form, and cohesion keeps the droplets on the needles.
Cohesion allows droplets to form, and specific heat keeps the droplets on the needles.
Adhesion allows droplets to form, and specific heat keeps the droplets on the needles.
___ 8.
A.
B.
C.
D.
Cells are largely made of organic compounds that contain carbon. Which property of the carbon atom makes it an essential component of organic compounds?
Carbon is a nonmental.
Carbon oxidizes to form carbon dioxide.
Carbon is solid at room temperature.
Carbon can form four covalent bonds.
A.
B.
C.
D.
Which statement describes the formation of a protein molecule?
Amino acids combine to form a protein chain
Fatty acid monomers dissolve to form a protein chain.
Fatty acid monomers combine to form a protein chain.
Amino acids dissolve monomers to form a protein chain.
___ 9.
Use the diagram below to answer question 10.
___ 10.
A.
B.
C.
D.
Which statement best describes the event shown in the diagram?
Glucose is being synthesized in the chloroplast using nitrogen from plants.
Amino acid monomers are joining together to form a protein macromolecule.
A polymer in the nucleus is being broken into its individual monomer subunits.
Lipid molecules are forming fatty acid chains in a dehydration synthesis reaction.
Use the table below to answer question 11.
___ 11.
A.
B.
C.
D.
Which two students correctly described organic compounds?
Students 1 and 2
Students 2 and 3
Students 3 and 4
Students 2 and 4
Use the information below for questions 12 and 13.
A scientist formed Chemical X in a laboratory. The material was then analyzed by other scientists. Analysis showed that the chemical was composed of long chains of repeated
CH2 molecules.
___ 12.
A researcher noticed that a similar CH 2 molecular structure was also located in the plasma membrane of an animal cell. The CH 2 molecular structure contained a
negatively charged phosphate groups. Which statement best describes the primary function of the CH2 and phosphate molecular structure located in the plasma
membrane?
A. It contains the genetic information needed for protein production.
B. It allows the energy that a cell needs to perform various life processes.
C. It allows a cell to regulate the movement of materials into and out of a cell.
D. It catalyzes specific chemical reactions in the cytoplasm of a cell.
___ 13.
A.
B.
C.
D.
Which type of organic molecule was most likely formed by the scientist in the laboratory?
Lipid
Protein
Carbohydrate
Nucleic acid
___ 14.
Carbonic anhydrase is an enzyme involved in the reaction of carbon dioxide with water to form a molecule that dissolves well in the liquid part of blood. How
does carbonic anhydrase affect this reaction?
A. by making the reaction reversible
B. by changing the chemical properties of the reaction
C. by increasing the time needed for the reaction to occur
D. by decreasing the amount of energy needed to complete the reaction
___ 15.
A.
B.
C.
D.
Plant cells use sunlight to make their own food. Which structure allows plants to perform this function?
nucleus
vacuole
chloroplast
mitochondrion
A.
B.
C.
D.
Which statement best explains why cellular respiration in plants and other organisms is dependent on photosynthesis?
Photosynthesis is one of the final steps in cellular respiration.
Photosynthesis provides the materials that fuel cellular respiration.
Photosynthesis absorbs excess energy produced by cellular respiration.
Photosynthesis absorbs materials that are catalyzed during cellular respiration.
___ 16.
Which graph best shows how enzyme activity changes as the temperature is adjusted above and below the enzyme’s optimum temperature?
___ 17.
___ 18.
A.
B.
C.
D.
A plant cell uses the molecules in the list to synthesize a protein. What role do the ATP molecules play in the protein synthesis process?
They provide energy.
The increase activation energy.
They convert energy into hereditary information.
They absorb excess energy to prevent overheating.
A.
B.
C.
D.
The diagram shows an energy transformation that typically occurs in plant cell plastids. Which statement best describes the role of plastids in the plant cell?
Chloroplasts transform light energy into chemical energy.
Mitochondria transform light energy into chemical energy.
Chloroplasts transform chemical energy into electromagnetic energy.
Mitochondria transform chemical energy into electromagnetic energy.
___ 19.
___ 20.
Using a microscope, a student observes a small, green organelle in a plant cell. Which energy transformation most likely occurs first within the observed
organelle?
A. ATP to light
B. Light to chemical
C. Heat to electrical
D. Chemical to chemical
Use the list below to answer question 21.
___ 21.
A.
B.
C.
D.
Which two statements correctly describe one similarities and one difference between cellular respiration and photosynthesis?
Statements 1 and 2
Statements 1 and 4
Statements 2 and 3
Statements 3 and 4
Use the list below to answer question 22.
___ 22.
A.
B.
C.
D.
The functions of which cell structure are described in this list?
Lysosome
Mitochondrion
Plasma membrane
Endoplasmic Reticulum
___ 23.
The rough endoplasmic reticulum and Golgi apparatus work together in eukaryotic cells. What is one way that the rough endoplasmic reticulum assists the Golgi
apparatus?
A. It assembles nucleic acids from monomers.
B. It breaks down old, damaged macromolecules.
C. It packages new protein molecules into vesicles.
D. It determines which protein molecules to synthesize.
Use the diagram below to answer question 24.
___ 24.
A.
B.
C.
D.
The indicated protein is part of a cell membrane. What is the most likely purpose of this protein?
It allows passage of particles into and out of the cell.
It manufactures phospholipids to repair membrane damage.
It releases stored chemical energy in membrane carbohydrates.
It attracts unbalanced electrical charges in the cell’s environment.
A.
B.
C.
D.
Which statement best describes how active transport differs from passive transport?
Only active transport requires ATP.
Only active transport moves small particles.
Only active transport relies on a plasma membrane.
Only active transport allows substances to leave a cell.
___ 25.
___ 26.
Carbon dioxide and oxygen are molecules that can move freely across a plasma membrane. What determines the direction that carbon dioxide and oxygen
molecules move?
A. Orientation of cholesterol in the plasma membrane.
B. Concentration gradient across the plasma membrane.
C. Configuration of phospholipids in the plasma membrane.
D. Location of receptors on the surface of the plasma membrane.
___ 27.
A sodium-potassium pump within a cell membrane requires energy to move a sodium and potassium ions into or out of a cell. The movement of glucose into or
out of a cell does not require energy. Which statement best describes the movement of these materials across a cell membrane?
A. Sodium and potassium ions move by active transport, and glucose moves by osmosis.
B. Sodium and potassium ions move by active transport, and glucose moves by facilitated diffusion.
C. Sodium and potassium ions move by facilitated diffusion, and glucose moves by osmosis.
D. Sodium and potassium ions move by facilitated diffusion, and glucose moves by active transport.
___ 28.
A.
B.
C.
D.
All living organisms must maintain homeostasis in order to survive. Which statement best describes one way humans maintain homeostasis?
Temperature is regulated by giving off carbon dioxide.
Water content is regulated by sweating.
Temperature is regulated by sweating.
Water content is regulated by sweating.
___ 29.
A.
B.
C.
D.
Which example is an activity that a fish most likely uses to maintain homeostasis within its body?
Using camouflage to avoid predators.
Feeding at night to regulate body temperature.
Moving to deeper water to regulate metabolic wastes.
Exchanging gases through its gills to regulate oxygen levels.
___ 30.
A jackrabbit has large ears containing blood vessels that help it maintain a constant body temperature by adjusting heat exchange with the surrounding
environment. Which characteristic of life is best described by this example?
A. Growth
B. Energy use
C. Organization
D. Homeostasis
Use the information to answer questions 31 and 32.
___ 31.
A.
B.
C.
D.
The function of which human organ is most like the cell walls of bacteria?
heart
liver
pancreas
skin
___ 32.
A.
B.
C.
D.
Which statement best describes how antibiotics affect cellular homeostasis?
Antibiotics remove chloroplasts from plant cells to cause starvation.
Antibiotics interfere with the transport of intracellular and extracellular materials.
Antibiotics increase the rate of DNA replication in human cells by forming nucleotides.
Antibiotics decrease the rate of cellular respiration in animal cells by producing oxygen.
CONSTRUCTED-RESPONSE ITEM
Use the information below to answer question 33.
Part A: Describe two similarities in the structure of the organic molecules shown.
Similarity 1: ____________________________________________________________________________________________________________________________________
________________________________________________________________________________________________________________________________________________
_______________________________________________________________________________________________________________________________________________
Similarity 2: ____________________________________________________________________________________________________________________________________
_____________________________________________________________________________________________________________________________ ___________________
________________________________________________________________________________________________________________________________________________
Part B: “Structure determines function” is an important concept in biology. Select one of the organic molecules shown and explain how its structure is related to its function.
________________________________________________________________________________________________________________________________________________
________________________________________________________________________________________________________________________________________________
_____________________________________________________________________________________________________________________________ ___________________
_______________________________________________________________________________________________________________________________________________
CONSTRUCTED-RESPONSE ITEM
Use the graph and diagram below to answer question 34.
34.
Part A: Explain how Enzyme A acts as a catalyst in the reaction.
Be sure to include energy and time in your answer
_____________________________________________________________________________________________________________________________ ___________________
________________________________________________________________________________________________________________________________________________
_____________________________________________________________________________________________________________________________ ___________________
_______________________________________________________________________________________________________________________________________________
Part B: Conditions around an enzyme change and affect the shape of the enzyme’s active sites. Predict how this would affect the enzyme’s ability to catalyze the reaction.
_____________________________________________________________________________________________________________________________ ___________________
________________________________________________________________________________________________________________________________________________
_____________________________________________________________________________________________________________________________ ___________________
_______________________________________________________________________________________________________________________________________________
CONSTRUCTED-REPONSE ITEM
Use the diagram below to answer question 35.
35.
Part A: Explain why ATP is important in biochemical reactions
_____________________________________________________________________________________________________________________________ ___________________
________________________________________________________________________________________________________________________________________________
_____________________________________________________________________________________________________________________________ ___________________
_______________________________________________________________________________________________________________________________________________
Part B. Give two examples of biochemical reactions and explain how an organism uses ATP within the reactions.
Example
Explanation
CONSTRUCTED-REPONSE ITEM
36. During physical education class, some students ran one mile. After their run, the students recorded the changes they experienced.
Select three changes experienced by the students and explain how each change can represent a homeostatic mechanism.
Change 1.
________________________________________________________________________________________________________________________________________________
________________________________________________________________________________________________________________________________________________
_____________________________________________________________________________________________________________________________ ____________
Change 2:
_____________________________________________________________________________________________________________________________ ___________________
________________________________________________________________________________________________________________________________________________
______________________________________________________________________________________________________________________________________________
Change 3: ______________________________________________________________________________________________________________________________________
_____________________________________________________________________________________________________________________________ ___________________
________________________________________________________________________________________________________________________________________________
_______________________________________________________________________________________________________________________________________________
BIOLOGY MODULE 2
MULTIPLE-CHOICE ITEMS
___ 1.
A.
B.
C.
D.
What must be transmitted to new DNA strands during replication maintain genetic information?
individual atoms from existing DNA strands.
individual sugars from existing DNA strands.
the sequence of bases from existing DNA strands
the sequence of phosphates from existing DNA strands
Use the illustrations below to answer question 2.
___ 2.
A.
B.
C.
D.
Which sequence lists the cell images in chronological order for mitosis?
1, 2, 3, 4
4, 3, 2, 1
1, 4, 3, 2
4, 2, 3, 1
Use the diagram below to answer question 3.
___ 3.
A.
B.
C.
D.
Which statement best describes the stage of mitosis shown in the illustration?
The cell is in telophase because the chromosomes are unpaired
The cell is in anaphase because the chromosomes have replicated
The cell is in prophase because the chromosomes have decondensed
The cell is in metaphase because the chromosomes are aligned
Use the diagram below to answer question 4.
___ 4.
A.
B.
C.
D.
Which part of the apple flower produces cells by meiosis?
Style
Anther
Stigma
Filament
A.
B.
C.
D.
Mitosis and meiosis are processes by which animal and plant cells divide. Which statement best describes a difference between mitosis and meiosis?
Meiosis is a multi-step process.
Mitosis occurs only in eukaryotic cells.
Meiosis is used in the repair of an organism.
Mitosis produces genetically identical daughter cells.
A.
B.
C.
D.
A carp, a type of fish, has 104 of chromosomes in its brain cells. How many chromosomes are contained in one of its gametes?
13
26
52
104
___ 5.
___ 6.
___ 7.
The genetic material of two different individuals of the same species is analyzed. One individual has brown eyes. The other has blue eyes. Which characteristic
for eye color would be the same for both individuals?
A. the allele
B. the DNA sequence
C. the amount of pigment
D. the location of the gene
___ 8.
A.
B.
C.
D.
Which effect is most likely caused by nondisjunction during meiosis?
an increase in nuclei
an extra chromosome
only two types of nitrogenous bases
increased survival benefits from traits
A.
B.
C.
D.
Which statement best describes the relationship between an allele and a gene?
An allele is a variation of a gene that can be expressed as a phenotype.
An allele is the part of a gene that attaches to messenger RNA molecules.
An allele is a segment of a DNA molecule that controls replication of a gene.
An allele is the primary protein made by a gene found in a developing embryo.
___ 9.
___ 10.
A trait in cows is determined by two alleles of a single gene: allele R is dominant, and allele r is recessive. What is the probability of the dominant trait being
expressed in the offspring of one RR parent and one rr parent?
A. 25%
B. 50%
C. 75%
D. 100%
___ 11.
Hemophilia is an inheritable genetic disorder that prohibits the proper formation of blood clots. The recessive gene that causes hemophilia is located on the Xchromosome. Given this information, which of the following statements is true?
A. In order for a male offspring to be a hemophiliac, his mother must be a hemophiliac.
B. In order for a female offspring to be a hemophiliac, her father must be a hemophiliac.
C. In order for a male offspring to be a hemophiliac, his father must be a hemophiliac.
D. In order for a female offspring to be a hemophiliac, her mother must be a hemophiliac.
Use the diagram below to answer question 12.
___ 12.
A.
B.
C.
D.
Which statement describes the diagram above?
DNA transcription is producing ribosomal RNA.
DNA translation is producing messenger RNA.
DNA transcription is producing messenger RNA.
DNA translation is producing ribosomal RNA.
___ 13.
A genetic mutation involving a single base causes an error that affects the sequence of the next 500 amino acids in a protein. Which type of mutation could have
produced this type of error in the protein?
A. silent
B. nonsense
C. frame-shift
D. substitution
Use the diagram below to answer question 14.
___ 14.
A.
B.
C.
D.
Which type of change in chromosome composition is illustrated in the diagram?
deletion
insertion
inversion
translocation
A.
B.
C.
D.
Which form of genetic engineering was used by humans for many years before the discovery of DNA?
Gene splicing
Gene insertion
Animal cloning
Selective breeding
___ 15.
___ 16.
New technologies enable cells to be extracted from plants to make renewable biodiesel fuel. Scientists have altered the genome of a specific plant species to
increase the amount of oil produced by each plant. Which statement explains why this technology most likely benefits farmers?
A. It makes each plant more resistant to disease.
B. It lowers the cost of each acre of plants cultivated.
C. It increases the value of each acre of land cultivated.
D. It eliminates the processing needed to extract plant oils.
___ 17.
A population of squirrels was separated during the formation of the Grand Canyon. Over time the squirrels, separated by the canyon walls and the Colorado
River, became unique species. Which mechanism most likely caused the development of the new species?
A. habitat preference
B. increased gene flow
C. geographic isolation
D. behavioral isolation
___ 18.
Overuse of antibiotics has caused antibiotic resistance in some bacteria in a population. Which statement describes the most likely impact of natural selection on
the bacterial population?
A. Beneficial mutations have decreased, resulting in a larger population than normal.
B. Only the genes for antibiotic resistance are now expressed, eliminating other genes.
C. More antibiotic-resistance bacteria have survived, resulting in more offspring with this trait.
D. The bacteria have become genetically isolated, resulting in decreased reproductive rates.
___ 19.
A researcher observes two species of frogs in the same area. Both species have a similar diet. One species breeds in fast-moving streams, while the other species
breeds in ponds. Both species are similar in appearance and have very similar DNA. Which information provides the best evidence that these two species descended from
a common ancestor?
A. the species’ similar diets
B. the species’ shared habitat
C. the species’ mating behaviors
D. the species’ physical characteristics.
___ 20.
In North America, the eastern spotted skunk mates in late winter, and the western spotted skunk mates in late summer. Even though their geographic ranges
overlap, the species do not mate with each other. What most likely prevents these two species from interbreeding?
A. temporal isolation
B. gametic isolation
C. geographic isolation
D. behavioral isolation
Use the statements below to answer question 21.
Statement 1: All living things are composed of cells.
Statement 2: If soil contains high levels of salt, the plants will die.
Statement 3: The temperature reading on the thermometer is 21C.
Statement 4: It must have rained this morning because the soil is wet.
___ 21.
A teacher lists four statements to interpret. Which table of information correctly distinguishes between the statements?
A.
B.
C.
D.
___ 22.
A.
B.
C.
D.
Which statement is a hypothesis?
The presence of an enzyme increased the reaction rate.
The reaction rate increased 100% once the enzyme was introduced.
Introducing an enzyme into a reaction did not increase the rate of the reaction.
When an enzyme is introduced into a reaction the reaction rate will increase by 100%.
A.
B.
C.
D.
A student studying the biosphere makes a list of biotic and abiotic characteristics of various biomes. Which characteristic is considered a biotic factor?
dry, sandy, nutrient-poor soil in a desert
less than 25cm of precipitation in a desert
evergreen trees present in a coniferous forest
temperature range of -40C to 40C in a grassland
A.
B.
C.
D.
Which description is the best example of a population?
all of the red foxes in a forest
all of the red foxes in every forest
all or the organisms in a forest
all of the organisms in every forest
___ 23.
___ 24.
Use the diagram below to answer question 25.
___ 25.
A.
B.
C.
D.
Which energy transfer most likely occurs between organisms in the food web?
from owl to fox
from rabbit to fox
from sparrow to grass
from mouse to grasshopper
___ 26.
A.
B.
C.
D.
Which example describes a mutualistic relationship between organisms?
Young wasps prey on caterpillars.
Crabs eat the remains of dead fish.
Ants protect a tree on which they feed.
Tapeworms feed on food in the intestines of cats.
___ 27.
Most of the water on Earth is located in the oceans and has a salinity of about 3.5%. Which statement best explains why rain is fresh water and has a very low
salinity?
A. When water precipitates from oceans, most of the salt remains in the oceans.
B. When water evaporates from oceans, most of the salt remains in the oceans.
C. When water precipitates from clouds, most of the salt remains in the clouds.
D. When water evaporates from clouds, most of the salt remains in the clouds.
___ 28.
Agricultural runoff can carry fertilizers into lakes and streams. This runoff can cause algae populations to greatly increase and then die off. Which effect does this
change in the algae population sizes most likely have on affected lakes and streams?
A. an increase in water level
B. an increase in water clarity
C. a reduction in dissolved oxygen needed by fish and shellfish
D. a reduction in temperature variations near the water’s surface
___ 29.
A.
B.
C.
D.
Why are nonnative species often considered a disturbance in an ecosystem?
They increase mutations.
They compete for resources.
They have special growth needs.
They cause increased biodiversity.
___ 30.
In Pennsylvania, a nonnative plant called stiltgrass out-competes native plants in many forest ecosystems. Which statement best describes how the spread of
stiltgrass negatively affects native herbivores?
A. Stiltgrass stops the life cycles of native herbivores.
B. Stiltgrass reduces the size of the native plant populations.
C. Stiltgrass increases the flow of energy through the ecosystem.
D. Stiltgrass attracts other nonnative plants to the forest ecosystem.
Use the information to answer questions 31 and 32 and the map to the right
___ 31.
The map indicates four locations of aye-aye-populations. Which location would most likely have an aye-aye population with the greatest variation in allele
frequencies?
A. Location 1
B. Location 2
C. Location 3
D. Location 4
___ 32.
A.
B.
C.
D.
For the aye-aye species, what is most likely the primary value of individuals living alone?
decreased space needs for the species
increased survival rates with habitat loss
reduced competition for natural resources
greater genetic variability within the species
CONSTRUCTED-RESPONSE ITEM
33. White-tailed deer from North America were brought to the islands of New Zealand around the year 1900. This species of deer has survived in several regions in New Zealand.
Part A: Explain why the white-tailed deer population is considered a nonnative species in New Zealand.
_____________________________________________________________________________________________________________________________ ___________________
________________________________________________________________________________________________________________________________________________
_____________________________________________________________________________________________________________________________ ___________________
Part B: Describe one possible effect that a nonnative species can have on a native ecosystem and explain why this effect might occur.
_____________________________________________________________________________________________________________________________ ___________________
________________________________________________________________________________________________________________________________________________
_____________________________________________________________________________________________________________________________ ___________________
Use the diagram below to answer question 34.
Part A: Using the pea flower color cross, identify the pattern of inheritance shown and explain how the cross shows this pattern.
_____________________________________________________________________________________________________________________________ ___________________
________________________________________________________________________________________________________________________________________________
_____________________________________________________________________________________________________________________________ ___________________
Part B: Explain how farmers could ensure that they only grow white flowers.
_____________________________________________________________________________________________________________________________ ___________________
________________________________________________________________________________________________________________________________________________
_____________________________________________________________________________________________________________________________ ___________________
Use the table below to complete question 35.
35. A Trichoplax is a simple multicellular animal that lives in water. This animal can reproduce asexually by simply dividing into two organisms
Part A: Describe a cellular division process that could be used by Trichoplax when it reproduces asexually.
________________________________________________________________________________________________________________________________________________
_____________________________________________________________________________________________________________________________ ___________________
_____________________________________________________________________________________________________________________________ ___________________
Part B: Describe one benefit and one limitation of how the Trichoplax can reproduce by simply dividing.
_____________________________________________________________________________________________________________________________ ___________________
________________________________________________________________________________________________________________________________________________
_____________________________________________________________________________________________________________________________ ___________________
Use the diagram below to complete question 36.
Part A: Identify the initial source of energy for the ecosystem.
_____________________________________________________________________________________________________________________________ ___________________
Part B: Using the table, complete a food chain that includes a producer, a primary consumer, and a secondary consumer.
Part C. The number of beavers in this ecosystem suddenly decreases. Describe the effect this may have on one other organism.
________________________________________________________________________________________________________________________________________________
_____________________________________________________________________________________________________________________________ ___________________
________________________________________________________________________________________________________________________________________________