AP Biology Module 4 Cell Cycle Review

Examine the image of a nerve cell. The diagram represents synaptic signaling in an animal. Which of the following is being released into the synapse in this model?

• Local regulators

• Neurotransmitters

• Relay molecules

• Receptor proteins

Which of the following best describes the evolution of cell communication in organisms?

• Because single-celled organisms do not use cell communication to survive, it most likely evolved after multicellular organisms.

• Cell communication does not occur in bacteria, suggesting it evolved after the emergence of multicellular organisms.

• Cell communication evolved early in the history of life because cell-signaling mechanisms are present in plants, animals, and bacteria.

• Signaling processes evolved independently across kingdoms because they all produce different cell communication hormones.

Which of the following best explains a method by which plants use long-distance signaling to carry out cell communication?

• Gas hormones are released and travel through the air to reach their target cells.

• Growth factors are released into extracellular fluid toward target cells via paracrine signaling.

• Molecules travel down a concentration gradient to target cells through plasmodesmata.

• Neurotransmitters carry chemical signals from dendrites to axons across synapses.

Which of the following correctly explains a long-distance signaling method animals use to perform cell communication?

• Chemical signals travel down a nerve cell and are converted to electrical signals at synapses.

• Endocrine cells release hormones that travel through the bloodstream to target cells.

• Local regulator molecules pass through gap junctions to transmit signals to target cells.

• Proteins on a cell's surface recognize and interact with molecules on another cell's surface.

Which of the following enzymes can rapidly remove phosphate groups from proteins?

• Adenylyl cyclase

• cAMP

• Protein phosphatases

• Protein kinases

Below is a model of a signal transduction pathway that results in the transcribing of mRNA. What is the best description of what would happen if the phosphorylation cascade resulted in a phosphate being attached to the transcription factor?

• mRNA would not stop being transcribed from the DNA.

• The phosphorylation cascade would continue to release excess phosphates.

• mRNA would stop being translated from the DNA.

• Receptor proteins would not bind to the signaling hormone.

What is the primary function of the phosphorylation cascade in the signal pathway mediation of gene expression?

• Amplification of the signal

• Conversion of transcription into translation

• Initiation of the signal

• Reduction of the hormone concentration

Researchers are studying the abnormal activity of kinases in relation to cancer. Theoretically, how might researchers use signal transduction pathways to influence the environment of cancer cells for treatment?

• Disrupt the function of protein kinases involved in cell cycle regulation

• Inactivate epinephrine receptors on cancer cells

• Stimulate production of cAMP in cancer cells

• Alter G protein-coupled receptors involved in cell cycle regulation to be active in the absence of their normal signaling molecules

Two cells are close to each other during early embryonic development. However, one of the cells becomes a muscle cell, while the other becomes a liver cell. What is the best explanation of why this occurs?

• They contain different DNA during the initial zygote formation.

• They receive different chemical signals in gene expression.

• They receive different electrical signals to activate DNA replication.

• They translate different genes from the same transcription.

How does the injection of insulin affect the signal transduction pathway of type 1 diabetics?

• Injected insulin prevents the glucose from binding to the cellular protein receptor.

• Insulin acts as a secondary messenger that cascades the message to allow glucose into the cell.

• Insulin is absorbed into the cytoplasm and binds with the transcription factor to make it active.

• Protein receptors on the cell bond to the insulin, which allows glucose to enter the cell.