AP Biology Unit 4 Flashcards

Questions and Answers

Which of the following best describes the role of cell-to-cell communication during a response to an invasion of antigens?

Chemicals secreted from antigen-presenting cells activate helper T cells. (correct)

Helper T cells initiate the production of antibodies.

Antigens directly kill invading pathogens.

Antibodies neutralize antigens without communication.

Which of the following statements best describes a primary function of plasmodesmata?

They enable photosynthesis.

They allow the movement of molecules from one cell to another. (correct)

They seal plant cells to prevent water loss.

They store nutrients for the plant.

Which of the following best explains a possible mechanism that would enable a hormone to efficiently reach all of the target cells in the body?

The hormone diffuses through the cell membranes.

The hormone is released into the bloodstream. (correct)

The hormone binds to a specific enzyme for transport.

The hormone is delivered directly to each cell by receptors.

Which of the following describes a critical role of cAMP during the transduction stage of a G protein signal transduction pathway?

It results in the activation of an enzyme that amplifies the signal. Signup and view all the answers

Which of the following best describes the component that metformin represents in a signal transduction pathway that regulates glucose production in the liver?

A ligand that activates the signal transduction pathway. Signup and view all the answers

What typically occurs first once a chemical messenger reaches a target cell?

A ligand binds to a receptor. Signup and view all the answers

Which of the following justifies the claim that differences in components of cell signaling pathways explain the different responses to epinephrine?

Only cells with receptors for epinephrine are capable of responding. Signup and view all the answers

Which statement provides the evidence to justify the claim that signal transduction may result in an altered phenotype?

If the SRY gene is absent or nonfunctional, the embryo will exhibit female sexual development. Signup and view all the answers

Which of the following statements best justifies the claim that changes in the expression of ced-9 in C. elegans can affect regulation of apoptosis in the cell?

An experiment showed a mutation in the ced-9 gene led to excessive cell death. Signup and view all the answers

Study Notes

Immune Response and Antigens

Antigens trigger immune responses in host organisms, recognized by specific antibodies produced by the immune system.
Cell-to-cell communication is vital in this process, where chemicals secreted by antigen-presenting cells activate helper T cells.

Plasmodesmata in Plant Cells

Plasmodesmata are narrow channels connecting adjacent plant cells through cell walls, allowing cytoplasmic communication.
Their primary function is to facilitate the movement of molecules between cells, enhancing intercellular communication.

Hormonal Signaling

Hydrophilic peptide hormones from the anterior pituitary gland target specific body cells.
These hormones are released into the bloodstream, enabling transportation to all cells possessing the appropriate receptors.

G Protein Signal Transduction

G proteins transmit extracellular signals to the interior of a cell upon activation by signaling molecules.
cAMP acts as a second messenger, activating enzymes that amplify the signal, significantly influencing the transduction process.

Metformin and Glucose Regulation

Metformin, used for treating type 2 diabetes, lowers glucose production in the liver by activating AMPK.
AMPK activation is essential for metformin’s inhibitory effects, as it cannot cross the plasma membrane independently, indicating it acts as a ligand in this signal transduction pathway.

Initial Steps in Signaling Pathways

The critical first step in a signaling pathway after a chemical messenger reaches a target cell is ligand binding to a receptor.

Epinephrine Response Variation

During fight-or-flight responses, epinephrine distributed via the circulatory system may elicit varied cellular responses based on receptor presence.
Only cells with epinephrine receptors can respond to the hormone, highlighting the importance of receptor availability in signaling pathways.

Signal Transduction and Phenotypic Changes

Changes in gene expression due to signal transduction can alter cellular functions and phenotypes, such as the SRY gene’s role in male sexual development.
Absence or dysfunction of the SRY gene leads to female sexual development, evidencing the impact of signaling pathways on phenotype.

Apoptosis in C. elegans

Researchers studied apoptosis in C. elegans to understand programmed cell death, identifying key regulating genes like ced-9 and ced-3.
A mutation in ced-9 results in excessive cell death, illustrating how changes in gene expression can affect apoptosis regulation.

Insulin Receptor Functionality

The insulin receptor, a transmembrane protein, regulates glucose homeostasis in the body by binding specific peptide hormones.

Description

Test your knowledge on the immune response and the role of antigens and antibodies with these AP Biology unit 4 flashcards. This quiz covers important concepts of cell-to-cell communication in the context of immune responses. Perfect for preparing for your exams and enhancing your understanding of biological interactions.