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

The diagrams show 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 some observations made by four students during a field trip to a nature area. Which student made observations of a community of organisms?

A science class is planning a field trip to a local farm that has a large pond. Which of the following lists the order of biological organization from smallest to largest that the students can expect to find at the pond?

Which of the following functions at the same organizational level as the kidney in the human excretory system?

A student is studying the ecology of a playa lake, which forms after a rainfall in a dry lake bed. The table lists the organisms that the student observed. Which level of biological organization has the student described in the table?

A table of four types of carbohydrates is shown. Which list correctly matches the functions to the types of carbohydrates?

Transmembrane proteins span the width of cell membranes. Four types of transmembrane proteins are shown in the section of cell membrane. Although these proteins have different specific functions, they all -

An advertisement for a health supplement for dogs claims to build lean muscle and strengthen tendons and ligaments, as well as provide energy. Which two biomolecules must the supplement contain to provide these benefits?

Two biomolecules are shown. Which of the following best describes these biomolecules?

Students were given a list of seven elements and asked to identify the four elements that are most abundant in biomolecules. Which table correctly identifies the four most-abundant elements in biomolecules?

Proteins and carbohydrates have many functions in the body of an organism. Specific proteins and carbohydrates perform specific tasks. Information about a protein and a carbohydrate is given below. How are Ferritin and Glycogen similar in their primary functions for an organism?

Four different nucleotides are used as building blocks of DNA. Which of the following can be used to distinguish one nucleotide from another?

The complex carbohydrates pictured below 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 -

A student preparing for a hike wants to pack a snack that has biomolceules 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?

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

Carbohydrates are more easily metabolized than lipids. However, on a gram-for-gram basis lipids provide cells with more -

Which of the following biomolecules typically contains both nitrogen and phosphates?

Proteins and polysaccharides are polymers. These polymers are formed by dehydration synthesis. Which statement correctly identifies a difference in the structure of proteins and polysaccharides?

Which of these best represents a fatty-acid molecule?

Students use 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 headings 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-celled organism can be classified as a prokaryote based on the absence of -

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?

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

A type of cellular transport is shown. Which description best identifies this type of cellular transport?

The diagram shows molecules that a mitochondrion uses to produces during a cellular process. Which other molecule is a product of this process?

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 the breathing rate during exercise?

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

When mammals get an infection, their internal body temperature often rises 2 to 3 degrees Celsius. The body gets the energy it needs to react to an infection by -

Which molecule synthesized by plants is a major source of energy for cellular processes in both plants and animals?

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?

In the early 1900's a scientist hypothesized a link between DNA and the production of proteins in the cytoplasm. However, the fact that DNA could not be found outside the nucleus led scientists to believe that another substance was also involved in the synthesis of protein in the cytoplasm. In the 1940's scientists performed an experiment that ultimately identified the site of protein synthesis. They also identified the molecule responsible for transporting information from the nucleus to the site of protein synthesis. What was this newly identified molecule?

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

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?

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?

Which group of organelles is directly responsible for the production of new molecules within a cell?

The cellular process known as the sodium-potassium pump was discovered int he 1950's by Jens Christian Skou, a Danish scientist: This process is a form of active transport that moves three sodium ions to the outside of a cell for every two potassium ions that it moves into the cell. Which of these best explains why energy is needed for active transport?

Which of these statements best explains the process of energy conversions that takes place in the mitochondria?

Which cellular process takes place in the ribosomes that are bound to the endoplasmic reticulum?

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?

Most plant leaves take in more carbon dioxide as light increases. They give off carbon dioxide if light intensity is too low. The graph shows a plant's carbon dioxide levels at different light intensities. At point X, the rate of which process is equal to the rate of photosynthesis?

Which of the following correctly describes how a diagram of cellular respiration would differ from a diagram of photosynthesis?

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 these data, the enzyme functions best at what temperature and pH?

Taq polymerase is an enzyme used in the polymerase chain reaction (PCR) to replicate fragments of DNA. A study published in 1976 examined the properties of Taq polymerase after the enzyme was isolated from Thermus aquaticus, a thermophilic bacterium that lives in the hot springs of Yellowstone National Park. The graph shows one of the results of the study. Which statement about enzyme activity is best supported by this graph?

Some foods that are rich in complex carbohydrates can be difficult to digest. Gas often forms as the foods are slowly digested by bacteria in the large intestine. The advertisement is for a nutritional supplement that prevents intestinal gas. Which of the following represents evidence that could be used to support the claims about this product?

The diagram represents one way an enzyme can be inhibited. Which statement explains the effect of an inhibitor on an enzyme?

People who have Alzheimer's disease experience an increasing loss of brain function and cognition over time. Alzheimer's is characterized by a buildup of abnormal protein fragments that damage brain cells. Recently scientists have discovered an enzyme, BACE2, that decreases these abnormal protein fragments in the brain of a person with Alzheimer's disease. Which statement explains how BACE2 most likely works?

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?

Lactose is found in milk products. It is converted by the body into a usable form in a species of chemical reactions. The diagram shows the series of reactions that convert lactose into a usable form. If Enzyme 2 is denatured, the levels of which substance will increase?

Pepsin and trypsin are two of the digestive enzymes that break down protein. A group of students studied the pH requirements of these enzymes. The graph below shows the results. The students found that pepsin functions best in an acid environment and trypsin functions best in a neutral environment. Based on their observations, pepsin most likely aids in digestion in which part of the human body?

Enzymes are proteins that help increase the rate of chemical reactions inside cells. These proteins are composed of many simpler molecules called amino acids. Which of the following suggests that the shape of an enzyme determines the enzymes's function?

A student produces a labeled drawing of a virus for a presentation. The student states that the capsid has a function similar to the nuclear membrane found in animal cells. Which of these describe the similar functions of capsids and nuclear membranes?

In 1898 Fredrich Loeffler and Paul Frosch found evidence that the cause of a highly contagious hoof-and-mouth disease in livestock was a microscopic 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?

In the 1880's, Louis Pasteur developed a method of weakening viruses. The weakened viruses could be injected into healthy individuals. How is this method effective in fighting viral diseases?

Which of these describes a difference between viruses and cells?

The human immunodeficiency virus (HIV) often infects and destroys CD4 T cells. Thes CD4 T cells are one of many kinds of white blood cells that are an important part of the immune system. The most common danger related to the destruction of CD4 T cells is -

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 1918 influenza epidemic killed between 50 million and 100 million people worldwide. This epidemic happened near the end of World War I. More people died from the influenza epidemic than were killed in the war. Which of the following explains why this virus was so deadly worldwide?

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 bacteriophage and E. coli alike?

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?

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. 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 intiviral agent to an infected person within 48 hours of the appearance of symptoms?

A person infected with the human immunodeficiency virus (HIV) may not have any symptoms for a period of time. During this period the virus affects the body by doing which of the following?

Severe acute respiratory syndrome (SARS) is an illness caused by a coronavirus. Symptoms including a high fever, headaches, and body aches typically occur two to seven days after infection by the virus. SARS is more serious in elderly patients. This information suggests that the reproductive cycle of the SARS virus is -

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

Cold sores are caused by the herpes simplex virus type 1. A company that wants to develop antiviral drugs would ask a research immunologist to study -

The karyotype, or chromosomal profile, for humans is shown. A karyotype can be used to investigate genetic disorders. The chemical colchicine is used in the production of karyotypes. Colchicine prevents spindle fibers from forming during the cell cycle. What is a result of preventing spindle fivers from forming?

Which table shows two steps of DNA replication?

The activities in the cell cycle occur during specific phases. In which phase of the cell cycle is DNA replicated?

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

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

People who have leukemia, a cancer that affects white blood cells, are often given Cytarabine. This drug inhibits the synthesis of DNA. Which phase of the cell cycle is most affected by Cytarabine?

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?

Cells pass through a G₂ checkpoint before entering mitosis. Ideally, if DNA damage is detected, the cells do not enter mitosis until the damage is repaired. Why is DNA damage repaired before cells enter mitosis?

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?

Scientists can bioengineer skin in a laboratory to treat severe burns and other types of skin injuries. This bioengineered tissue is grown from living cells. The cellular process that enables the cells to grow and develop into tissue is?

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 inters the G₂ stage of the cell cycle?

Telophase is a stage of a cellular process that begins after the chromosomes have moved to opposite poles of the cell. During which cellular process does telophase occur?

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

Which of these must occur during S phase of the cell cycle so that two daughter cells can be produced during M phase?

The diagram shows how specialized body cells can develop. Which of the following best explains why cells that contain the same genetic material do not develop into the same types of cells?

What is the role of mRNA in expressing specialized structures?

From a single fertilized ovum undergoing a series of rapid cell divisions, a human infant develops. The embryonic cells become specialized for a variety of functions. Which of these statements best describes how different cell types develop?

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

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?

Cell differentiation is critical during embryonic development. The process of cell differentiation results in the production of many types of cells, including germ, somatic, and stem cells. Cell differentiation is most directly regulated by -

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 they 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 obstruct blood flow and, therefore, oxygen supply to target organs. A major component of atherosclerosis is the excessive reproduction of smooth muscle cells of the blood vessels. Certain drugs may have the potential to reverse or prevent the unregulated reproduction of the diseased blood-vessel cells. Which of these processes is the most likely target of these drugs?

The diagram represents the cell cycle. When cells have 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?