The picture shows a student using a microscope to study a prepared slide of a single-celled organism. A single-celled organism can be classified as a prokaryote based on the absence of —

Different types of mutations can occur in DNA. The diagram represents a type of mutation. Which statement describes the mutation in the diagram?

Part of the cell cycle is shown in this simplified model. This part of the cell cycle is best described as the process that —

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. The results provide evidence that —

In gel electrophoresis a DNA sample from an unknown donor is placed in a small well at one end of a special gel-coated plate. Samples from known donors are placed in other wells on the plate. An electric current is passed through the plate, causing the DNA fragments to separate. The size and location of the separated fragments can be compared for similarities. The more similar the locations and sizes of the fragments, the more closely the donors of the samples are related. The diagram shows four samples being compared with an unknown sample. The donor of which sample is most closely related to the donor of the unknown sample?

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 conditions cause the contractile vacuole to fill with water?

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

A student used poster board to construct this model of a section of DNA. Which statement describes this model of DNA?

The arctic fox inhabits northern areas of North America. The same arctic fox is shown in the drawing at different times of the year. What causes this change in fur color?

The four butterflies in the illustrations represent the offspring in the F1 generation. Which statement is best supported by the phenotypes of these offspring?

The initial steps in gene expression are modeled below. Double-stranded DNA first unwinds into two strands. Which process and product are represented in Diagram 2?

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

This diagram shows cellular activity across a cell membrane. Which two processes does this diagram most directly model?

The table shows a DNA sequence and three types of mutations that can change the DNA sequence. Which mutation will cause translation to stop?

The picture shows a 3-D 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?

The table lists and describes three types of cells from prepared slides that students observed with a microscope. Which of these sets of slides could students have used for their observations?

The photograph shows a laboratory investigator examining samples of DNA in a procedure called PCR, or polymerase chain reaction. Using PCR, the investigator can create thousands or even millions of copies of a fragment of DNA for closer investigation. In which of these situations would PCR be most useful?

Each strand of a DNA molecule contains nitrogenous bases that pair with other nitrogenous bases in very specific ways. A diagram of a section of DNA is shown. Which DNA strand is complementary to the one shown above?

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?

Part of an important cellular process involving a DNA strand is modeled below. What is the purpose of this cellular process?

Models of the human immunodeficiency virus (HIV) and an animal cell are shown below. What is the difference in the function of the glycoprotein structures of an HIV virion and the cilia of an animal cell?

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?

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

The table below lists the types of white blood cells found in humans, indicates how abundant they are, and describes their functions. The two most abundant types of white blood cells may both be involved in a response to which of these?

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

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?

Some students used 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?

H1N1 flu is a highly contagious viral infection caused by the influenza A (H1N1) virus. The symptoms of H1N1 flu are listed in the box below. An antiviral agent administered within 48 hours of the appearance of symptoms can reduce the severity of the illness. Why is it important to administer an antiviral agent to an infected person within 48 hours of the appearance of symptoms?

Four different types of cells are shown below. Which characteristic is shared by all four cells?

Checkpoints occur between the stages of the cell cycle. If a cell does not meet certain criteria at the end of a stage, it will not move to the next stage. Which of these occurs just before the cell enters the G2 stage of the cell cycle?

The picture below shows a person’s karyotype. Which of the following can best be determined by examining this karyotype?

Researchers Robert Briggs and Thomas King used ultraviolet radiation to destroy the nuclear DNA of frog eggs. Nuclei from adult skin cells and from tadpole-gut epithelial cells were cultured and then injected into eggs that had their nuclei destroyed. The results were tadpoles. Which conclusion is supported by the data from this investigation?

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?

Which of the following polypeptides is coded for by the mRNA sequence 5' AUGGUUAAACGACAAUCC3'?

In 1952 Rosalind Franklin took the x-ray photograph shown below, which gave the world its first look at DNA. By studying this photograph, scientists gained knowledge about the —

A photograph of a virus is shown below. The projections on the surface of this virus allow the virus to —

A section of a nucleic acid is shown below The process represented in the diagram produces a molecule that is complementary to the template strand of DNA. What type of molecule is produced?

A photomicrograph of onion root tip cells during mitosis is shown below. Which phase of mitosis is occurring in the cell indicated by the arrow?

A model of a DNA molecule is shown below. The arrow indicates —

A codon chart is shown below. Which of these changes to the DNA triplet 3’ GCT 5’ will affect the protein produced?

The diagram below represents the cell cycle. When cells leave the cell cycle, they exit during G1 phase and then enter G0 phase, a resting period. Most normal cells can leave G0 phase and reenter the cell cycle at G1 phase before entering S phase. Cancer cells are different because they cannot enter G0 phase and are likely to do which of the following?

The results shown in the picture were obtained using a technique known as gel electrophoresis. This technique separates mixtures of DNA. In the picture nine different samples of DNA are compared. Gel electrophoresis can be used to -

The diagram illustrates the activity of vesicles during a cellular process. Which statement best explains the function of the vesicles?

A sequence of a DNA template strand is shown. Which of these is the correct amino acid chain produced from the DNA template strand?

The Himalayan rabbit's habitat has cold, snowy winters and mild summers. The body is typically covered in white fur except for the nose, feet, tail, and ears, which are covered in black fur. A scientist shaved an area of white fur on the back of a Himalayan rabbit and placed an ice pack over the shaved area. The shaved area grew black fur. Which of these best explains why the hair that grew back where the ice pack was placed was black and not white?

Students are given data from an investigation that identified some of the chemical elements present in four different samples.

In cattle the allele for cloven hooves (H) is dominant over the allele for mule-foot hooves (h). The phenotype for each trait is shown in this picture. What is the probability of cloven hooves in the offspring of parents that are heterozygous for the trait?

In the early 1900s, Thomas Hunt Morgan was among the first scientists to contribute to the chromosome theory of heredity. Morgan's investigations into heredity in fruit flies led him to propose that the event represented in the diagram sometimes occurs. Which statement about the event represented in the diagram is valid?

Some components of cells are listed. Which of the components could be observed using a microscope in a prepared slide of leaf epidermal cells but not in a prepared slide of human cheek cells?

A student groups different types of cells as shown. Which table headings should the student use for the two groups?

This model of the cell cycle includes two arrows that each represent a process in the cycle. What do the two arrows represent?

A certain mutation in the gene for hemoglobin results in the red blood cells becoming sticky, rigid, and irregularly shaped. These irregularly shaped red blood cells block the flow of blood throughout the body. A single base mutation is responsible for these irregularly shaped blood cells.Which of these mutations most likely results in the mutated hemoglobin gene?