Scientists estimate that there are more than 20,000 species of ants. The species range in size from 1 mm long to 38 mm long and live in most environments. The diets of ants range from flowers and seeds to fluids from their own larvae. Ants have been able to successfully inhabit so many different environments because their populations have been able to --

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?

The picture shows bean-shaped glands called nodes. The clusters of cells in the nodes include macrophages that break down viruses and other potentially harmful materials. Nodes also contain cells that produce protein particles capable of capturing harmful materials that flow in tissue fluid through the nodes. Different parts of the body are drained by nodes in different regions of the body.

Which body systems are directly responsible for regulating these nodes and protecting the body from harmful materials in tissue fluid?

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 -

Part of an important cellular process involving a DNA strand is modeled in the image. (View image)

What is the purpose of this cellular process?

The energy pyramid shows the energy made available by producers. (View Image)

Base 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?

Nitrogenous bases are located on both strands of the DNA double helix. What is the significance of the nitrogenous bases?

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?

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

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

Viruses can be transmitted through air, water, food, insect bites, and direct skin contact. Once a virus gains entry to the body, it invades a host cell in order to --

The diagram shows cells in different phases of mitosis. A student is trying to find a cell in a particular phase of mitosis. The student is looking for evidence that spindle fibers are separating the chromosomes to ensure that each new nucleus has one copy of each chromosome. (View Image)

Which cell is in the phase of mitosis that the student is searching for?

Albinism is an autosomal recessive condition. Which circle graph shows the genotype probability when an albino female mates with a male that is heterozygous for the albinism trait? (View Image)

The complex carbohydrates pictured (View Image) are made by linking molecules of glucose.

In all three complex carbohydrates, the subunits of glucose are bonded together differently. Because they have different structures, they most likely --

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

Four common relationships between organisms are listed in the box. (View Image)

Which statements best describe these relationships?

The diagram represents one way an enzyme can be inhibited. (View Image)

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

Which biomolecule is responsible for insulation and long-term energy storage?

This infectious viral disease has many symptoms that range from chills, coughing and sneezing to fever, muscle aches, nausea and vomiting. These symptoms show up within 2 to 7 days after our cells become infected. What is the viral reproduction cycle of this virus?

What mutation has occurred here?

T-G-A-C-C-A

T-G-A-G-C-A

Some female peacocks prefer males with large, colorful tales while other female peacocks prefer males with no tail at all. Females are now mating only with the tail they prefer. What type of reproductive barrier is this?

A segment of DNA produces methionine, threonine, histidine, aspartate, and glycine when translated. A substitution mutation occurs and causes the synthesis of the segment as shown. Which is the new peptide chain when the new DNA segment is translated?

On March 24, 1989, an oil tanker ran aground on Bligh Reef in Prince William Sound, Alaska, and spilled millions of liters of crude oil. The graph shows pink salmon populations in Prince William Sound from 1970 to 1999. What do these data suggest about the effect the oil spill had on pink salmon?

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 —

A student preparing for a hike wants to pack a snack that has biomolecules that provide quickly available energy but few excess calories. Which nutrition label lists the best combination of biomolecules that provide quickly available energy while providing the fewest calories from other types of biomolecules?

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?

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?

The model represents the change in the DNA content of a cell during the cell cycle. Which part of the model represents the S phase?

Cells can generate as many as 36 to 38 molecules of adenosine triphosphate (ATP) from the metabolism of one molecule of glucose. Which cellular process results in this amount of ATP production?

A segment of DNA is represented in the illustration. How is information for a specific protein carried on the DNA molecule?

Fireflies emit light. The production of light by an organism is called bioluminescence. To generate visible light, cells in a firefly’s tail produce thousands of luciferase enzymes. Luciferase binds to a chemical called luciferin. Once bound, the luciferase enzyme speeds up a chemical reaction that combines an oxygen molecule and luciferin to produce oxyluciferin. This reaction requires energy and releases light. Which of the following best describes how the luciferase enzyme speeds up the chemical reaction?

An analysis of DNA and RNA sequences can be used to classify organisms. A dendrogram, such as the one shown below, is based on molecular data. It can be used to represent evolutionary relationships within a group of organisms that are hypothesized to have descended from a common ancestor. Which statement is best supported by the information in this dendrogram?

Facial dimples and free earlobes are both considered dominant human traits. What are the expected phenotypes of the offspring of a female with dimples and free earlobes (DDFf) and a male with no dimples and attached earlobes (ddff)?

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

A cladogram is shown below. All the animals to the right of the hagfish would have the common characteristic of —

The differences between two molecules include the type of sugar that forms a section of the molecules and the identity of one of the four nitrogenous bases that make up another section of the molecules. These two molecules are —

Some students used vinegar to dissolve away the shells of three 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.

Plants have developed many methods of seed dispersal. The table below shows seeds of two different plants. Plants have developed many methods of seed dispersal. The table below shows seeds of two different plants.

A student builds a model of a DNA strand. Which of these models of a DNA strand shows bases that are complementary to the ones on the student’s DNA model?

Three species of lizards of the genus Gallotia are found on the Canary Islands, a chain of seven volcanic islands off the west coast of Africa. The easternmost island, Lanzarote, is the oldest, while the westernmost island, El Hierro, is the youngest. The distribution of lizard species is shown on the map below. Which statement about the ancestry of the lizards from the genus Gallotia is best supported by this information?

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 —

In the 1960s the molecular biologist George Streisinger developed the strand-slippage hypothesis. Streisinger noticed that mutations 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?

Normal fruit flies have brownish-yellow bodies, and this body color is dominant. A mutation in the gene for body color can produce flies with an ebony body color. A homozygous normal fruit fly (e+e+) is crossed with a homozygous ebony fruit fly (ee). What is the predicted outcome of this genetic cross?