Biology 1201 Final Exam 2025, Bio 1201 Test Bank,

• | P a g e

Biology 1201 Final Exam 2025, Bio 1201 Test Bank, Biology Exam Questions and Answers, Introductory Biology Final, Biology 1201 Study Guide, College Biology Test Bank, Biology 1201 Review

Which of the following statements about lipid-soluble hormones is true?

• They act by producing second messengers.
• They act by affecting the transcription of genes.
• They bind to DNA as soon as they enter a cell.
• They bind to receptors on the plasma membrane. -

ANSWER-B. They act by affecting the transcription of genes.

Based on your understanding of membrane permeability, the signal molecules (ligands) binding to the cytoplasmic receptors are _______.

• polar molecules
• non-polar molecules
• could be both - ANSWER-B. non-polar molecules 1 / 4

• | P a g e

The signal molecule Leptin is 16000 Da protein. Where would you expect to find the receptors of this molecule?

• cytoplasm
• cell membrane
• I don't know - ANSWER-B. cell membrane

Protein signal molecules are not permeable to the cell membrane but can affect their target cells because

• intracellular receptors are present only in the target cells
• all of the other cells quickly destroy the signal molecules.
• the target cells have cell membrane bound receptors specific

to the signal molecule.

• only the target cells have the appropriate DNA sequence that

must be activated.

• cells, which are the target, transport the signal molecule

directly to the nucleus. - ANSWER-C. the target cells have cell membrane bound receptors specific to the signal molecule.

Which of the following is true of a target cell? 2 / 4

• | P a g e

• It must use G-proteins
• It must use a tyrosine-kinase pathway
• It must use c-AMP
• It must have a second messenger
• It must have a receptor for the chemical signal - ANSWER-E.

It must have a receptor for the chemical signal

Transduction - ANSWER-the action or process of converting something (especially energy or a message) into another form

Describe the G-Protein transduction pathway. - ANSWER-A G- protein receptor binds to the signaling molecule, becoming activated. The G-protein binds to the activated receptor, adding GTP. The GTP activates the G-protein and will bind to the enzyme, activating it. The signal molecule is then kicked off, creating a cellular response.

In what sensory system are G-proteins found? - ANSWER- olfactory

Which of these is a logical signal transduction pathway? 3 / 4

• | P a g e

• An intracellular receptor activates phospholipase C, which

cleaves a membrane protein to form IP3, which then activates the opening of an ER channel protein, which releases cyclic AMP into the cytoplasm, where it binds to an intracellular enzyme that carries out a response.

• A receptor tyrosine kinase activates adenylyl cyclase, which

activates phospholipase C, which converts ATP into cyclic AMP, which binds to an intracellular enzyme that carries out a response.

• An ion-channel receptor opens, allowing a steroid hormone to

enter the cell; the steroid hormone then activates protein kinases that convert GTP to GDP, which binds to an intracellular enzyme that carries out a response.

• A G-protein-linked receptor activates G protein, which

activates phospholipase C, which cleaves a membrane lipid to form IP3, which binds to a calcium channel on the ER, wh - ANSWER-D. A G-protein-linked receptor activates G protein, which activates phospholipase C, which cleaves a membrane lipid to form IP3, which binds to a calcium channel on the ER, which opens to release calcium ions into the cytoplasm, which bind to an intracellular enzyme that carries out a response.

Describe the tyrosine kinase transduction pathway. - ANSWER- Tyrosine kinase is a large protein with a ton of tyrosine residues

• / 4