Lipid molecules embedded in the cell membrane that provide structural integrity and flexibility to the cell
Enzymes that catalyze the breakdown of waste products within the cellular cytoplasm, ensuring homeostasis
Specific molecular structures, usually proteins, that bind to signaling molecules (ligands) or detect stimuli, triggering a cellular response through signal transduction pathways
Transmembrane channels that passively transport ions and small molecules across the cell membrane down their concentration gradients
Tap an answer to check it.
WhyReceptors are usually proteins that bind signalling molecules or detect stimuli, triggering cellular responses.
2Multiple choice
What term is used for a signalling chemical that binds to a receptor?
Catalyst
Substrate
Enzyme
Ligand
Tap an answer to check it.
WhyA ligand is the signalling chemical that binds specifically to a receptor.
3Multiple choice
Which statement regarding quorum sensing is true?
Does not involve oxygen
Involves the enzyme luciferin
Cell signalling by bacteria
V. fischeri is a terrestrial bacterium
Tap an answer to check it.
WhyQuorum sensing is cell-to-cell signalling by bacteria that responds to population density.
4Multiple choice
Which marine bacterium uses quorum sensing for bioluminescence?
Vibrio fischeri.
Escherichia coli.
Salmonella typhimurium.
Bacillus subtilis.
Tap an answer to check it.
WhyVibrio fischeri uses quorum sensing to trigger bioluminescence once its population is dense enough.
5Multiple choice
Which of the following is an example of a signalling chemical in animals?
Cellulose, a structural polysaccharide found in plant cell walls
Lignin, a complex polymer providing rigidity to plant cell walls
Chlorophyll, a pigment essential for photosynthesis in plants
Insulin, a hormone that regulates blood glucose levels
Tap an answer to check it.
WhyInsulin is a hormone signalling chemical that regulates blood glucose levels.
6Multiple choice
Neurotransmitters are examples of what category of signaling chemicals?
Signalling chemicals in animals.
Bacterial quorum sensing molecules.
Plant growth regulators.
Viral replication factors.
Tap an answer to check it.
WhyNeurotransmitters are signalling chemicals used by animal nervous systems at synapses.
7Multiple choice
What chemical groups can hormones belong to?
Enzymes, coenzymes, and vitamins.
Amines, proteins, and steroids.
Carbohydrates, lipids, and nucleic acids.
Sugars, starches, and fibers.
Tap an answer to check it.
WhyHormones can be amines, proteins/peptides, or steroids depending on their chemistry.
8Multiple choice
Which of the following can serve as neurotransmitters?
Amino acids, peptides, amines, and nitrous oxide
Cholesterol, a lipid involved in cell membrane structure and steroid hormone synthesis
Cellulose, chitin, and lignin
Insulin, a hormone involved in glucose regulation
Tap an answer to check it.
WhyNeurotransmitters include amino acids, peptides, amines, and gases like nitric oxide.
9Multiple choice
What is the main difference between hormones and neurotransmitters in terms of their effects?
Hormones have distant effects, while neurotransmitters have localized effects.
Hormones are fast-acting, and neurotransmitters are slow-acting.
Hormones work in the cytoplasm, and neurotransmitters work on the cell surface.
Hormones are proteins, and neurotransmitters are lipids.
Tap an answer to check it.
WhyBlood-borne hormones act on distant targets, whereas neurotransmitters act locally across synapses.
10Multiple choice
How are hormones typically transported?
Through the blood system.
Via the lymphatic system.
Through direct cell-to-cell contact.
By diffusion across a synaptic gap.
Tap an answer to check it.
WhyHormones are secreted into and transported around the body by the bloodstream.
Ready to test yourself?
Practise Chem. Signal. with instant marking and progress tracking.