Specific molecular structures, usually proteins, that bind to signaling molecules (ligands) or detect stimuli, triggering a cellular response through signal transduction pathways
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
Transmembrane channels that passively transport ions and small molecules across the cell membrane down their concentration gradients
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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?
Ligand
Enzyme
Substrate
Catalyst
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WhyA ligand is the signalling chemical that binds specifically to a receptor.
3Multiple choice
Which statement regarding quorum sensing is true?
Cell signalling by bacteria
Involves the enzyme luciferin
V. fischeri is a terrestrial bacterium
Does not involve oxygen
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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.
Bacillus subtilis.
Salmonella typhimurium.
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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?
Insulin, a hormone that regulates blood glucose levels
Lignin, a complex polymer providing rigidity to plant cell walls
Chlorophyll, a pigment essential for photosynthesis in plants
Cellulose, a structural polysaccharide found in plant cell walls
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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.
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WhyNeurotransmitters are signalling chemicals used by animal nervous systems at synapses.
7Multiple choice
What chemical groups can hormones belong to?
Amines, proteins, and steroids.
Carbohydrates, lipids, and nucleic acids.
Sugars, starches, and fibers.
Enzymes, coenzymes, and vitamins.
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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
Insulin, a hormone involved in glucose regulation
Cholesterol, a lipid involved in cell membrane structure and steroid hormone synthesis
Cellulose, chitin, and lignin
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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 work in the cytoplasm, and neurotransmitters work on the cell surface.
Hormones are proteins, and neurotransmitters are lipids.
Hormones are fast-acting, and neurotransmitters are slow-acting.
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WhyBlood-borne hormones act on distant targets, whereas neurotransmitters act locally across synapses.
10Multiple choice
How are hormones typically transported?
Through the blood system.
By diffusion across a synaptic gap.
Through direct cell-to-cell contact.
Via the lymphatic system.
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WhyHormones are secreted into and transported around the body by the bloodstream.
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