In 1898 Friedrich Loeffler and Paul Frosch found evidence that the cause of the highly contagious hoof-and-mouth disease in livestock was a microscope infectious particle. It was discovered that this particle requires a host cell to reproduce.

Which pathogen is most likely responsible for causing hoof-and-mouth disease in livestock?

Which of these describes a difference between viruses and cells?

The human immunodeficiency virus (HIV) often infects and destroys CD4 T-cells. These CD4 T-cells are one of many kinds of white blood cells that are an important part of the immune system, which protect the body.

The most common danger related to the destruction of CD4 T cells is -

The picture shows a 3D model of a virus called a bacteriophage. Bacteriophages can infect bacteria such as E.coli.

In what way are the bacteriophage and E.coli alike?

A team of students encounters an unknown organism in a field while conducting a biodiversity study. Some students think the organism is a plant, while others think it is a fungus.

Which question should the students investigate to classify the organism correctly?

Which list correctly identifies characteristics that protists share with animals?

Five general characteristics of organisms in kingdoms Plantae or Fungi are listed in the box.

Which table correctly lists the characteristics of the organisms in the two kingdoms?

A student wants to use the Venn diagram below to show the characteristics of two kingdoms of organisms. The characteristics that the two kingdoms share will be listed in the shaded area where the circles intersect.

Which of these is a characteristic that the student should list in the shaded part of the diagram?

The diagram shows taxonomic groups and a major distinguishing characteristic of all but two of them.

Which characteristic will be used to complete the chart ?

Male guppies found in areas without predators are more colorful than the ones found in locations with large predator populations. A population of adult guppies originating from an area with a large number of predators is transferred to a nearby area with few predators.

Which of these is most likely to happen over a few generations?

The diagram shows light and dark colored beetles that live on a tree. Which result is most likely to occur to the beetle population due to predation over time?

The quiver tree grows in desert areas in southern Africa. In recent decades, average temperatures have been rising in southern Africa. Scientists predict that this warming trend will continue. Quiver trees in the hottest parts of their range near the equator are dying, but quiver trees at high elevations or in parts of the range that are farther from the equator are growing and reproducing.

Which of these best explains what is happening to the quiver tree population in southern Africa?

An experiment is run where 50 beige mice and 50 black mice are placed on dark volcanic rock. Over the next 25 years, which type of mouse do you expect to be the majority?

Which term refers to the process by which individuals that are better suited to the environment survive and reproduce therefore passing down their genes to their offspring?

This cladogram shows the evolutionary relationships among some mammals based on homologous structures.

Which statement is supported by this cladogram?

Scientists can determine relatedness among organisms by comparing partial amino acid sequences. The table shows four partial amino acid sequences from four organisms.

Which organism is the least related to the other three organisms?

The image shows part of the humerus bone in different genera of primates.

Which statement is best supported by the observable structures of the different humorous bones?

Cetaceans are whales and their relatives. The diagram shows some fossils of cetaceans.

Which statement provides the best evidence that Ambulecetus natans is an ancestor of Basilosaurus iris?

Bactrian camels, dromedaries, llamas, and alpacas are all members of the same taxonomic family, Camelidae. Members of this family all have two toes, no hooves, true canine teeth, and a split upper lip. the family Camelidae originated in North America. The physical features of animals in this family and the family's geographical origin provide evidence that all these animals -

When cells lose their ability to regulate the cell cycle, they can divide at an accelerated rate and form a mass of cells. This mass of cells is referred to as -

Oncogenes are mutated forms of genes. Oncogenes can transform a cell into a tumor cell. Some tumor cells are benign, while others are malignant. How does the presence of an oncogene lead to the formation of a tumor?

Cells typically respond to DNA damage in three ways: by ceasing to grow and divide until the damage is repaired, by permanently ceasing to grow and divide, or by dying. In 2010 a group of scientists reported that a certain kind of immune reaction can cause DNA damage that leads to a fourth response. DNA damage can turn off genes involved in cell-signaling pathways. Turning off these genes can cause less-mature cells to divide too rapidly, often leading to the development of -

Atherosclerosis is a disease that obstructs blood flow and, therefore, oxygen supply to target organs. A major component of atherosclerosis is the excessive reproduction of smooth muscle unregulated reproduction of the diseased blood-vessel cells. Which of these processes is the most likely target of these drugs?

$$$$  The diagram represent the cell cycle.

When cells leave the cell cycle, they exit during G-1 phase and then enter G-0, a resting period.  Most normal cells can leave G-0 phase and reenter the cell cycle at G-1 phase before entering S phase.  

The gray squirrel, Eastern fox squirrel, and red squirrel are all different species of squirrels. Why is having a scientific name for each species of an organism important?

Organisms are classified today using the Linnaean system, and the following table shows the taxonomic classification of two marine organisms living along the Pacific Coast.

Taxonomic classification is important to marine biologists because it provides a way to -

Scientists around the world use a standardized taxonomic system. Why would scientists want to use a taxonomic system that is standardized?

Adult mountain lions (Puma concolor) are almost 2 meters long. They have a black spot over each eye. The common names used throughout the United States for this species are listed below.

Why is it best for scientists to use the name from the standardized taxonomic system?

The Linnaean taxonomic system classifies organisms into divisions called taxa. If two organisms belong to the same taxonomic group, they are related. Similarity at which of these levels indicates the closest relationship?

The diagrams show a partial food web containing the Glyptapanteles wasp and the life cycle of this wasp.

Based on the two diagrams, which list correctly identifies the relationships Glyptapanteles wasp larvae have with other organisms?

Which of these best demonstrates mutualism between certain types of bacteria and humans?

In North American forests, two species of birds, nuthatches and brown creepers, forage on the same trees for insects. Brown creepers feed on insects found near the bottom of the tree trunk, while nuthatches feed on insect in the top part of the tree.

The difference in foraging behavior most likely affects the nuthatches and brown creepers by -

A remora is a fish that has an adhesive disk on the back of it head that it uses to attach itself to a large shark. When food floats away from the shark's mouth as it feeds, the remora collects the scraps. drawing of a shark with a remora attached and a remora's adhesive disk is shown below.

The relationship between the remora and the shark is an example of -

A student performed an investigation in which two ivy plants were planted in two separate containers that had earthworms mixed in with the soil, and the other container has soil and no earthworms. The plants were given the same amount of water and exposed to the same amount of sunlight. The student observed that after several weeks of growth, the plant exposed to earthworms appeared to be healthier and exhibited more growth. To conclude that the relationship between the plant and the earthworm is an example of mutualism, the student must perform follow-up investigations that do which of the following?

Which diagram demonstrates how crossing-over contributes to genetic variety during meiosis?

Human body cells each have 46 chromosomes in their nuclei. Meiosis is necessary in order to ensure that each gamete produced in the human body has-

Sexual reproduction in animals depends on the production of gametes. Which of these processes produces gametes in animals?

Crossing-over between nonsister chromatids during meiosis is significant in heredity. This process most likely leads to an increase in which of the following?

A mutation that occurs in the gametes of an organism will most likely be transferred to which of the following?

A codon chart is shown.

Which of these changes to the DNA triplet 3' GCT 5' will not affect the protein produced?

Sickle-shaped red blood cells result from a mutation in the gene that codes for hemoglobin. This mutation results in sickle-cell anemia. A partial sequence of bases from a normal hemoglobin gene and a sequence that results in sickle-cell anemia are shown below.

What type of mutation is depicted in this sequence?

Early-onset Alzheimer's disease affects peope under the age of 65. Less than five percent of people who are diagnosed with Alzheimer's disease have this type. Many cases of early-onset Alzheimer's disease are inherited, a type is known as familial Alzheimer's disease (FAD). Which statement is best supported by this information?

In the 1960s the molecular biologist George Streisinger developed the strand-slippage hypothesis. Streisinger noticed that mutation occurred in areas of DNA that contained many repeated sequences. When a strand-slippage error occurs, an insertion mutation can result. How does the insertion mutation affect the DNA?

Mice have two unlinked allele pairs that affect fur color. The table shows how allele pairs affect fur color. The term "agouti" describes fur with pigmentation that changes in each hair from the shaft to the tip, giving the fur a banded appearance. Mice with the aa allele pair are albino, regardless of the second allele-pair combination.

What is the probability of albinism in the offspring of a cross between two mice with AaBb

In humans blood type is determined by the A, B , and O alleles. The A and B alleles are codominant to each other and dominant over the O allele. An individual with the AO genotype and an individual with the BO genotype can produce offspring with which of the following phenotypes?

A new predator of rabbits has been introduced within an ecosystem. This new predator runs faster than the native predator of rabbits.

Which statement describes what will most likely occur in the rabbit population due to the introduction of the predator?

The aye-aye lemur is a mammal that fees mostly on insect larvae that live inside trees. The aye-aye lemur ha a specialized middle finger that is long and thin. The aye-aye lemur moves along a tree branch and taps the branch with its specialized finger. When the aye-aye lemur hears a difference in the echo, it will tear open the bark with its teeth until the insect tunnel is exposed. The aye-aye lemur then uses its specialized finger to reach the insect larvae and remove it.

Which selective pressure most likely resulted in the development of the aye-aye lemur's special adaptation ?

The white tail cattail is a hybrid species of plant that is a result of the cross between broad-leaved cattail and the narrow-leaved cattail. Over time, the white cattail has established itself in the wetlands of Midwestern states.

Which of these explains the success of the white cattail ?

Adaptations that result from natural selection are expected to increase the fitness of an organism. In terms of natural selection, which of the following best describes fitness ?

In the 1040s, the scientist J. B. S. Haldane linked may human red blood cell disorders with the tropical regions where malaria occurs. Haldane hypothesized that the widespread presence of these red blood cell disorders as well as traits that protect individuals from malaria were the result of natural selection. Haldane's hypothesis was later confirmed by the research of A. C. Allison.

The resistance to malaria carried by individuals in areas where malaria is widespread is the result of --

Which diagram demonstrates how crossing-over contributes to genetic variety during meiosis?

Human body cells each have 46 chromosomes in their nuclei. Meiosis is necessary in order to ensure that each gamete produced in the human body has-

Sexual reproduction in animals depends on the production of gametes. Which of these processes produces gametes in animals?

Crossing-over between nonsister chromatids during meiosis is significant in heredity. This process most likely leads to an increase in which of the following?

Enzymes are proteins that have a three-dimensional shape that is specific to a particular substrate. environmental conditions can change the shape of the protein.

What is the most likely result if the shape of the enzyme changes?

The graphs show the reaction rate for an enzyme across a range of temperatures and pH.

Based on this data, this enzyme functions best at what temperature and pH?

The diagram represents one way an enzyme can be inhibited.

Which statement explains the effect of an inhibitor on an enzyme?

Alzheimer's disease, which is loss of brain function and cognition over time, is caused by a buildup of abnormal protein fragments that damage brain cells. The BACE2 enzyme decreases the abnormal protein fragment in the brain of people who suffer from Alzheimer's disease.

Which statement explains how BACE2 most likely works?

Which of these components are found in the cells of all living organisms?

Scientist use zebra fish to study human genetic diseases because zebra fish and humans share many of the same genetic diseases.

Which statement describes why zebra fish experience similar genetic diseases as humans?

Researchers combined sequences of fruit-fly DNA from a gene for a particular trait with frog DNA. The mixture was heated to separate the DNA strands. Cooling allowed the single strands to form pairs. The researchers observed that some of the fruit-fly DNA paired with frog DNA.

In the early 1980s scientists were able to produce two biomolecules by splicing a human gene into the bacterium E. coli to make recombinant human insulin and growth hormone. Which statement best explains why this experiment was successful?

Organisms can be classified based on homology, which is shared characteristics inherited from a common ancestor. In the past, homologies were based on studies of anatomical structures and patterns of embryonic development. In more recent years, the use of molecular biology techniques has allowed homologies to be compared at the level of nucleotide sequences. Nucleotide sequence comparisons are possible because all organisms share which of the following?

What would be the most likely effect of a wildfire that burned a large area of a forest?

As part of the nitrogen cycle, animals acquire some amino acids by doing which of the following?

This diagram demonstrates why the ocean is a larger carbon sink.

An increase in the amount of carbon dioxide in the atmosphere can cause atmospheric temperatures to increase. which statement explains how this could affect the ocean as a carbon sink?

Atmospheric nitrogen has to be combined with other elements, or fixed, in order to be used by plants. Lightning is one way that nitrogen is fixed.

when lightning occurs, the extreme heat breaks the bonds in nitrogen to combine with oxygen and form nitrogen oxides. In what ways is most of the nitrogen fixed by lightning made available for use by plants?

The diagram shows the flow of organic molecules through an ecosystem. One process that occurs in the ecosystem is labeled X, and another process that occurs is labeled Y.

Which two processes are identified by eh labels X and Y?

Which statement accurately describes the energy needs for photosynthesis and cellular respiration?

Which statement explains how producers are dependent upon consumers for their survival ?

Photosynthesis and cellular respiration both involve the use and release of gases. Which statement correctly identifies the role of gases in the two processes?

Which statement best describes the relationship between the products of photosynthesis and the reactants in cellular respiration?

Diatoms are one of the most common types of phytoplankton in marine habitats. Like plants, diatoms contain chlorophyll and produce glucose from which of the following?

Students are modeling mRNA during the process of protein synthesis. Which answer choice correctly describes the model of mRNA strand being transcribed?

Which of these is the correct amino acid chain produced from the DNA template strand?

A model of a biological process is shown above. What is the purpose of this process?

The initial steps in gene expression are modeled in the picture above. Double-stranded DNA first unwinds into two strands.

Which process are products are represented in Diagram 2?

Part of an important cellular process involving a DNA strand is modeled below.

What is the purpose of this cellular process?

A dichotomous key for identifying fish is shown.

Based on this key, which two fish have eyes located on either side of their head and are not spotted?

Many tree frog populations are threatened due to habitat loss. In an effort to promote conservation, tree frogs may be bred in captivity. A zoo acquired male and female tree frogs from two different populations. In the zoo, the tree frogs were able to successfully mate within their own population, but breeding attempts between the two populations were unsuccessful.

Based on this information, which statement correctly describes the relationship between the two populations of tree frogs.

A student used a microscope to study four members of the phylum Ciliophora. Members of this phylum move when propelled by hundreds of tiny cilia.

Although these organisms belong to the same phylum, they are classified as different -

The relationships among different orders of millipedes are shown in the cladogram.

Based on this cladogram, which statement best describes relationships among millipede orders?

Simple leaves have a single leaf on a petiole, or stem, while compound leaves have more than one leaflet on a petiole. This unknown leaf can be identified using the dichotomous key.

Which tree does the unknown leaf come from?

During secondary succession, which of these best describes why decomposing pioneer plants give way to larger more complex plants species, such as hardwood trees?

grassland ecosystem in Texas have evolved to depend on periodic fires to return nutrients to the soil and encourage plant reproduction. humans have prevent fires in many of these grassland areas, resulting in plant and animal communities with tlittle diversity. wildlife biologists often recommend purposefully stating fires called prescribed burns. which are moonitored and controlled, in grassland ecosystems every 3 to 4 years. These biologists observe greater diversity in plant and animal life in the years following a prescribed burns.

What natural processes are the biologist attempting to imitate?

A small town in the piney woods of East Texas has a soccer field composed of native grasses. The soccer field is mowed once a week.

What effect does continual mowing have on the ecology of the field?

An estuary collects sediments from the ocean and rivers that feed into it. The sediments swirl around and then settle to form a mudflat. Eel grass is then established on the mudflat. The ecosystem changes over time and ultimately develops into a salt marsh that contains mangrove trees.

Which of the following is likely NOT involved in this example of ecological succession?

The rocky material left behind by a retreating glacier forms what is called a moraine. When primary succession occurs on a moraine, which life forms will help create the soil by breaking down bare rock?

Gibberellins are hormones produced in the root tips of plants. The plant uses these hormones to stimulate the growth of shoots.

How are gibberellins able to affect other parts of the plant?

A chart of some plant systems and functions is shown.

Which system interactions are dependent on the plant's ability to respond to the direction of light?

Plant roots have extensions called root hairs. These root hairs. These root hairs are important in the homeostasis

of the plant.

Which statement best explains the importance of the root hair to the stems and leaves of the plant?

A corn plant produces both male and female flowers. The male flower forms the tassel and the female flower forms the ear of corn. The silk that emerge from the ear are the stigma of the female flower. Each silk leads to an ovule that can become a corn seed.

Which of these must happen for corn seeds to develop on the ear?

Fruits grown in hot climates are usually less sweet than those grown in cooler temperatures. The high temperatures increase the rate of respiration in the plants, thus reducing the sugar content in some fruits.

Why does increased respiration in the leaves and stems reduce the sugar content in the fruits of a plant?

Gibberellins are hormones produced in the root tips of plants. The plant uses these hormones to stimulate the growth of shoots.

How are gibberellins able to affect other parts of the plant?

A chart of some plant systems and functions is shown.

Which system interactions are dependent on the plant's ability to respond to the direction of light?

Plant roots have extensions called root hairs. These root hairs. These root hairs are important in the homeostasis

of the plant.

Which statement best explains the importance of the root hair to the stems and leaves of the plant?

A corn plant produces both male and female flowers. The male flower forms the tassel and the female flower forms the ear of corn. The silk that emerge from the ear are the stigma of the female flower. Each silk leads to an ovule that can become a corn seed.

Which of these must happen for corn seeds to develop on the ear?

Fruits grown in hot climates are usually less sweet than those grown in cooler temperatures. The high temperatures increase the rate of respiration in the plants, thus reducing the sugar content in some fruits.

Why does increased respiration in the leaves and stems reduce the sugar content in the fruits of a plant?

CRISPR-Cas 9 is a genetic modification technique that edits parts of the genome of an organism. Using this technique, scientists can add, remove, or modify sections of the DNA sequence.

How can scientists use this technique to control gene expression?

Human bone muscle and nerve cells all contain the same number of chromosomes with the same complement of genes. What enables these cells to perform specialized activities?

At birth, Himalayan rabbits are usually white over their entire bodies. However, when parts of their bodies reach temperatures below 35 degrees Celsius, a pigment that causes these parts to turn black is produced. Which of the following is most likely the cause of this phenomenon?

In 1917, the biologist Thomas Hunt Morgan conducted studies in which he kept some caterpillars in the dark and places some others under red, green, or blue lights. Exposure to red light produced butterflies with brightly color wings. Exposure to green light resulted in dark-colored wings. Exposure to blue light or no light resulted in pale-colored wings. What was the most likely conclusion of Morgan's research?

CRISPR-Cas 9 is a genetic modification technique that edits parts of the genome of an organism. Using this technique, scientists can add, remove, or modify sections of the DNA sequence.

How can scientists use this technique to control gene expression?

Human bone muscle and nerve cells all contain the same number of chromosomes with the same complement of genes. What enables these cells to perform specialized activities?

At birth, Himalayan rabbits are usually white over their entire bodies. However, when parts of their bodies reach temperatures below 35 degrees Celsius, a pigment that causes these parts to turn black is produced. Which of the following is most likely the cause of this phenomenon?

In 1917, the biologist Thomas Hunt Morgan conducted studies in which he kept some caterpillars in the dark and places some others under red, green, or blue lights. Exposure to red light produced butterflies with brightly color wings. Exposure to green light resulted in dark-colored wings. Exposure to blue light or no light resulted in pale-colored wings. What was the most likely conclusion of Morgan's research?

The San Marcos salamander, Eurycea nana, is a light reddish-brown translucent salamander about 2-5 cm in length. E. nana is found only in Spring Lake and a portion of the San Marcos River.

Which human activity would most likely decrease the ability of the salamanders to survive?

In the mid-1980s an aggressive strain of algae known as Caulerpa was accidentally introduced into the Mediterranean Sea when a seaside aquarium cleaned out its tanks. The algae contain a toxin that prevents native herbivores from consuming it. Caulerpa quickly spread over the seafloor, crowing out many species including sponges, corals, sea fans, and lobsters.

Which statement explains the most likely impact Caulerpa has had on the biodiversity in the Mediterranean Sea?

Scientist have observed many types of tropical fish moving beyond their traditional ocean ranges into waters that have historically been more temperate. These fish compete for food with native fish, consuming much from the kelp forests and beds of sea grass.

Roads are often built through forests for industrial purposes or as land is developed for residential and commercial needs. How would road construction through a forest most likely affect the ecosystem?

Food webs such as the one shown were first used in 1927 by the animal ecologist Charles Elton. The food web below represents the feeding relationships among organisms in an Alaskan ecosystem.

an environmental change that removed which of these organisms from the ecosystem would cause the most instability in the ecosystem?

A partial Texas food web is shown.

The populations of which organisms will most likely increase as a result of a disease that suddenly reduced the population of Texas horned lizards?

A biomass pyramid of an ecosystem is shown.

Which statement provides the best explanation for the difference in biomass of organisms found at each trophic level?

The table lists some organisms found in a swamp ecosystem and their sources of energy.

When constructing an energy pyramid of the swamp ecosystem, which of these would be placed at the top of the pyramid?

A partial meadow food web is shown.

Based on this food web, which organisms are direct sources of energy for secondary consumers?

The energy pyramid below shows the energy made available by producers.

Based on the energy flow between trophic levels in an energy pyramid, how much energy would be expected to be found at the secondary consumer level in this pyramid?

Which four body systems interact to allow a person to sneeze?

The fuzzy millipede, Polynexus fasciculatus, is found in Texas and is preyed upon by most species of ants. To protect itself against the ants, it ejects fibers from a tuft located at the tail end of its body. The tufts have hooks at the tips and barbs along their length that lock and interlink with the ant's setae, small hairs that cover the body of the ant. When an ant attacks, the millipede flexes its back end toward the ant and wipes the tufts against it. As the ant attempts to remove the tufts, it entangles itself more, becoming immobilized.

Which two systems most directly interact in the fuzzy millipede's defense against ants?

A feedback mechanism in the human body is shown.

Based on this diagram, which two systems interact to maintain homeostasis?

The female reproductive and endocrine systems work interactively for which main purpose?

How do the circulatory system and immune system work together to respond to an injury?

Some species of millipedes will roll into a ball when threatened, while other species of millipedes can secrete noxious chemicals from their bodies.

These adaptations allow the millipedes to -

The Indian leaf butterfly has traits that allow it to resemble a leaf. The bright colors of the monarch butterfly indicate that the butterfly tastes bad and can be poisonous.

How does the appearance of these butterflies help them to survive?

The table below provides some information about the feeding methods of the five rhinoceros species.

Which rhinoceros species is best adapted for feeding in the large open grasslands of Africa's Serengeti ecosystem?

Which answer choice best describes a community?

The human body is composed of organ systems. Which list represents a system organized from least to most complex?

The diagram shows some of the levels of biological organization.

In what order are the levels in the diagrams?

Recent studies in bone research indicate that using ultrasound on a broken bone can decrease the healing time by 25%. Which of these are the most basic levels of organization involved when a bone heals?

The table shows observations made by four students during a field trip to a nature area.

Which student made o0berservations of a community of organisms?

What is the role of mRNA in expressing specialized structures?

As a fertilized egg divides, the cells differentiate because they -

Animal develop from a single fertilized egg. The embryonic cells become specialized for a variety of functions.

Which of these statements best describes how different cells types develop?

How does RNA and DNA differ?

Which of the following describes RNA?

Conservation biologists studying cheetah populations have determined that the lack of genetic diversity among the cheetahs is due to genetic drift.

Which statement explains the most likely consequence of having a low genetic diversity on the cheetah population?

Common baboons live on the savanna in breeding groups called troops. While females tend to stay with the troop, younger or less dominant males may leave to join a neighboring troop. Which of these is a likely outcome of movement by young males ?

Two populations of mice living in the same forest are separated by a large water-filled ditch. After a rainstorm, flooding brings several mice from one population to the other population. When the mice from the first population reproduce with members of the second population, which of the following will likely occur?

Lord Howe Island is a volcanic island in the Tasman Sea that is about 11 km long and 2.8 km wide. The island has two species of palm trees, Howea forsteriana, and the more abundant Howea belmoreana. The two species do not interbreed even when they grow very close to each other. Which evolutionary process fails to occur ?

The concept of gene flow is demonstrated when a cow is driven off from its hers, joins another herd, and reproduces. When the cow contributes to the gene pool of the new herd, which of these most likely increases?

Students using a microscope to look for structures present in four different cells. the students placed an X for each structure that was viewed for each cell on the table shown.

Which cell that was viewed is most likely a prokaryote?

A student groups different types of cells as shown.

Which table heading should the student use for the two groups?

The picture shows a student using a microscope to study a prepared slide of a single-celled organism.

A single-cell organism can be classified as a prokaryote based on the absence of -

4. Some students used the information they gathered from lab investigations to prepare a table. They entered the table in their lab notebooks.

Which of these correctly identifies the two cells described in the table?

Both euglena (eukaryote) and cyanobacteria (prokaryote) are photosynthetic unicellular organisms found in pond water. The feature that distinguishes euglena from cyanobacteria is the -

White-tailed deer are seasonal breeders. female white-tailed deer begin their reproductive cycle in the fall. Rising testosterone levels in male white-tailed deer cause them to start their breeding season around the same time. Offspring are born the following spring and summer.

What is the most likely explanation for white-tailed deer having a seasonal breeding cycle instead of a monthly breeding cycle like many domesticated animals?

The green frog (Liithobathes clamitans clamitans) is found in many parts of the United States. The table contains some information about this frog.

Why does the ability to lay 1,000 to 5, 000 eggs increase the fitness of the species L. clamitans clamitans?

What condition is essential for natural selection to result in a new species ?

Which description best identifies this type of cellular transport?

In a study of physical endurance, researchers observed significant increases in the heart rates and breathing rates of participants immediately after they engaged in strenuous exercise.

Which statement best explains the increase in the heart rate and breathing rate during exercise?

The picture shows a contractile vacuole of a unicellular freshwater organism. The contractile vacuole regulates the flow of water into and out of the cell in an aquatic environment.

What condition caused the contractile vacuole to fill with water?

This diagram shows cellular activity across a cell membrane.

Which two process does this diagram most directly model?

Some students used vinegar to dissolve away the cells of these eggs and used these eggs as models of human red blood cells. The students observed the changes in the eggs when they were placed in different solutions.

Which statement best describes the role of the cell membrane in this model?

Which role of protist has the most positive effect on maintaining the plant population in an ecosystem?

Saprophytes are fungi that feed on dead and decomposing organisms. They secrete enzymes that digest components of cell walls, such as cellulose and lignin.

Which statement explains why these fungi are an important part of the biogeochemical cycle?

A student researching bacteria concluded a report with the claim in the box.

Which statement correctly addresses the validity of the claim?

Some fungi secrete substances that are toxic to bacteria that compete with them for food. Scientists have used their knowledge of this ability of fungi in order to produce which of the following substances?

A student sets up a compost bin outdoors. Inside the bin, microorganisms convert the student's vegtable and paper scraps into rich fertilizer. Which of the following best describes the role that these microorganisms play in natural habitats?

The diagram shows data on the evolution of horses.

The date in the diagram is evidence that -

Niles Eldredge and Stephen Jay Gould researched the lenses of the eyes of fossil trilobites of different species. In 1972 they published a paper in which they described the tendency of a species to remain the same un5il a sudden change in the environment causes a new related species to appear.

Which hypothesis was most challenged by the work of Eldredge and Gould?

The graph shows the number of taxa of reptiles whose fossilized tracks have been found.

Which statement is best supported by this data?

This diagram of the fossil record represents changes in mollusks over millions of years.

How can the pattern of changes in the fossil record best be explained?

The cladogram shows the evolution of land plants as indicated by fossil records.

Which discovery would challenge the validity of this cladogram?

Male guppies found in areas without predators are more colorful than the ones found in locations with large predator populations. A population of adult guppies originating from an area with a large number of predators is transferred to a nearby area with few predators.

Which of these is most likely to happen over a few generations?

The diagram shows light and dark colored beetles that live on a tree. Which result is most likely to occur to the beetle population due to predation over time?

The quiver tree grows in desert areas in southern Africa. In recent decades, average temperatures have been rising in southern Africa. Scientists predict that this warming trend will continue. Quiver trees in the hottest parts of their range near the equator are dying, but quiver trees at high elevations or in parts of the range that are farther from the equator are growing and reproducing.

Which of these best explains what is happening to the quiver tree population in southern Africa?

An experiment is run where 50 beige mice and 50 black mice are placed on dark volcanic rock. Over the next 25 years, which type of mouse do you expect to be the majority?

Which term refers to the process by which individuals that are better suited to the environment survive and reproduce therefore passing down their genes to their offspring?