In the early 1900s 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 1940s 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?

Which of these describes a difference between viruses and cells?

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

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 nucleus has one copy of each chromosome. Which cell is the phase of mitosis that the student is searching for?

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 type of cells?

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 -

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?

The diagram 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?

A segment of a DNA strand is shown. 3' AGGTCAGGT 5'. Which of these is the correct complementary DNA strand for the segment shown?

Which part of a DNA molecule is responsible for the direct coding of specific traits in an organism?

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

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

CRISPR-Cas9 is a genetic modification technique that edits part 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?

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 the 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?

The model shows a mutation to a partial sequence of bases in a gene. Which type of mutation does the model demonstrate?

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?

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 alleles?

In cattle the allele for cloven hooves (H) is dominant over the allel 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?

Gamete produced by an organism contain a combination of genes from that organism. In every gamete, this combination is --

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

Which list correctly identifies characteristics that protists share with animals?

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?

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

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. How are ferritin and glycogen similar in their primary functions for an organism?

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

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?

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, this enzyme functions best at what temperature and pH?

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

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?