10.0 COORDINATION

Which of the followings a true statement about the threshold potential of a membrane

• It is equal to about 35 mV

• It is equal to about 70 mV

• It opens voltage-sensitive gates that result in the rapid outflow of sodium ions

• It is the depolarization that is needed to generate action potential

Saltatory conduction is a term applied to conduction of impulses

• Across electrical synapses

• Along the postsynaptic membrane from dendrite to axon hillock

• In two directions at the same time

• Along myelinated nerve fibers

Neurotransmitters are released from presynaptic membrane to synaptic cleft by process of

• Osmosis

• Diffusion

• Active transport

• Exocytosis

The role of calcium ions during the muscle contraction is to

• Form tropomyosin-troponin complex

• Bind with tropomyosin to expose the myosin head

• Deactivates ATPase on myosin binding site on action

• Bind with troponin to allow the formation of cross-bridges

During muscle contractions,

• The myofilaments shorten

• The actin filaments move towards the middle of sarcomere

• The actin and tropomyosin filamens slide over each other

• Cross-bridges of myofilaments are formed permanently

Where are neurotransmitter receptors located?

• On the nuclear membrane

• At Nodes of Ranvier

• On the presynaptic membrane

• On the postsynaptic membrane

Steroid hormone-receptor complexes formed in

• the lysosome

• the plasma membrane

• the cytoplasm

Which of the following is TRUE of a non-steroid hormone action mechanism?

• Hormone binds with a specific receptor on the cell membrane

• Hormone binds with the receptor in the cytoplasm

• Hormone crosses the cell membrane

• mRNA is produced

In order to flower, a short-day plant needs a

• night that is longer than a certain length

• day that is longer than a certain length

• lash of red light during a long dark period

• high level of Pfr

Which type of neuron transmits a signal from a sense organ to the central nervous system?

• sensory
• relay
• motor
• efector