Question

Q1) What is not true of signal-transduction pathways?

A		They are often made-up of a series of kinases
B		They transduce signals from water-soluble hormones to stimulate a cellular response
C		They are typically initiated by the binding of a hormone to a cytoplasmic receptor protein
D		They allow amplification of a hormonal signals
E		They allow regulation a hormonal signal by other molecules

Q2) When you touch a hot object you automatically pull your hand away as a reflex. Which part of your nervous system is not involved in this response?

A		Spinal ganglia
B		Sensory receptors
C		Sensory neurons
D		Cerebellum
E		Motor neurons

Q3) Which is the best explanation of why action potentials can only move in one direction along an axon.

A		Because voltage-gated Na+ channels are unable to open during membrane repolarization.
B		Because voltage-gated Na+ channels are unable to open during membrane depolarization.
C		Because voltage-gated K+ channels are unable to open during membrane depolarization.
D		Because voltage-gated K+ channels are unable to open during membrane repolarization.

Q4) Which of the following components of the immune system is not correctly matched with its function?

A		Interferons – protection of cells from viral attack
B		Mast cells – allergic response to pollen
C		Plasma cells – clonal response of B cells
D		Cytotoxic T cells – activation of complement proteins
E		Helper T cells - Interleukin-2

Answer 1

Q1) Not true of signal-transduction pathways?

A. They are often made-up of a series of kinases - True

Signal transduction is the process by which a physical or chemical signal is transmitted through a cell as a series of molecular events, most commonly protein phosphorylation catalyzed by protein kinases, which ultimately results in a cellular response.

B. They transduce signals from water-soluble hormones to stimulate a cellular response - True

Water-soluble hormones bind to a receptor protein on the plasma membrane of the cell.

C. They are typically initiated by the binding of a hormone to a cytoplasmic receptor protein - False

Water-soluble hormones bind to a receptor protein on the plasma membrane of the cell. Receptor stimulation results in a change in cell activity, which may send feedback to the original hormone-producing cell.

D. They allow amplification of a hormonal signals - True

Hydrophilic hormones must interact with cell membrane receptors and are typically associated with a G protein, which becomes activated when the hormone binds the receptor. Amplified as the signaling pathway progresses.

E. They allow regulation a hormonal signal by other molecules - False

Q2) A. Spinal ganglia - false

Spinal ganglia is a cluster of nerve bodies positioned along the spinal cord at the dorsal and ventral roots of a spinal nerve.

B. Sensory receptors - True

Sensory receptors are dendrites of sensory neurons specialized for receiving specific kinds of stimuli.

C. Sensory neurons - False

Sensory neurons are nerve cells within the nervous system responsible for converting external stimuli from the organism's environment into internal electrical impulses.

D. Cerebellum - False

The cerebellum receives information from the sensory systems, the spinal cord and other parts of the brain and then regulates motor movements.

E. Motor neurons - False

A motor neuron (motoneuron) is a neuron whose cell body is located in the motor cortex, brainstem or the spinal cord and axon (fiber) projects to the spinal cord or outside of the spinal cord to directly or indirectly control effector organs, mainly muscles and glands.

Q 3. Action potentials move in one direction. This is achieved because the sodium channels have a refractory period following activation, during which they cannot open again.

Ans; B. Because voltage-gated Na+ channels are unable to open during membrane depolarization.

Q 4 A. Interferons – protection of cells from viral attack - Correct

B. Mast cells – allergic response to pollen - Correct

C. Plasma cells – clonal response of B cells - Correct

D. Cytotoxic T cells – activation of complement proteins - Correct

E. Helper T cells - Interleukin-2 - False