AP bio Unit 4

Which of the following is a type of local signaling in which a cell secretes a signal molecule that affects neighboring cells?

• hormonal signaling

• autocrine signaling

• paracrine signaling

Hormones are chemical substances produced in one organ that are released into the bloodstream and affect the function of a target organ. For the target organ to respond to a particular hormone, it must _____.

• modify its plasma membrane to alter the hormone entering the cytoplasm

• be from the same cell type as the organ that produced the hormone

• experience an imbalance that disrupts its normal function

• have receptors that recognize and bind the hormone molecule

When a neuron responds to a particular neurotransmitter by opening gated ion channels, the neurotransmitter is serving as which part of the signal pathway?

• relay molecule

• transducer

• signal molecule

• response molecule

Which of the following types of signaling is represented in the figure?

• autocrine

• paracrine

• hormonal

• synaptic

A G-protein receptor with GTP bound to it _____.

• is in its active state

• signals a protein to maintain its shape and conformation

• will use cGMP as a second messenger

• directly affects gene expression

Testosterone (a hormone) functions inside a cell by _____.

• acting as a signal receptor that activates tyrosine kinases

• binding with a receptor protein that enters the nucleus and activates specific genes

• acting as a steroid signal receptor that activates ion channel proteins

• coordinating a phosphorylation cascade that increases spermatogenesis (sperm generation)

One of the major categories of receptors in the plasma membrane reacts by forming dimers, adding phosphate groups, and then activating relay proteins. Which type does this?

• G protein-coupled receptors

• ligand-gated ion channels

• steroid receptors

• receptor tyrosine kinases

A drug designed to inhibit the response of cells to testosterone (a hormone) would most likely result in _____.

• lower cytoplasmic levels of cAMP

• a decrease in transcriptional activity of certain genes

• an increase in cytosolic calcium concentration

• a decrease in G protein activity

Binding of a signaling molecule to which type of receptor leads directly to a change in the distribution of ions on opposite sides of the membrane?

• receptor tyrosine kinase

• G protein-coupled receptor

• ligand-gated ion channel

• intracellular receptor

Lipid-soluble signaling molecules, such as testosterone, cross the membranes of all cells but affect only target cells because _____.

• only target cells retain the appropriate DNA segments

• intracellular receptors are present only in target cells

• only target cells possess the cytosolic enzymes that transduce the testosterone

• only in target cells is testosterone able to initiate the phosphorylation cascade leading to activated transcription factor