1. Response to external stimulus is called _______________
a) reaction
b) immunity
c) response
d) irritability
Explanation: All organisms respond to external stimulus, a property known as irritability. Even the smallest amoeba and bacterial cell possess this feature. In response to external stimulus, a cell may activate from its whole range of metabolic pathways
2. Information is coded in the form of fast moving impulse in which types of cells?
a) epithelial
b) endothelial
c) neurons
d) hepatocytes
Explanation: Nerve cells are called neurons; they conduct, transmit and collect information in form of electrical impulses. The structure of neurons is unique and different from other cells in the body.
3. Which part of a neuron receives information from other neurons?
a) cell body
b) axon
c) dendrites
d) myelin sheath
Explanation: The fine extensions from cell body of the neurons are called dendrites which receive information from external sources, usually other neighboring neurons.
4. The information is forwarded from the neuron through which part?
a) axon
b) soma
c) dendrites
d) nucleus
Explanation: Axon is a single prominent extension that emerges from the cell body and is responsible for conducting outgoing impulses away from the cell and towards other cells.
5. Myelin sheath is composed mainly of _____________
a) proteins
b) lipids
c) nucleic acids
d) cholesterol
Explanation: Myelin sheath surrounds the axon which extends from the soma of a neuron. Myelin sheath is composed mainly of lipids and their function is to prevent loss of impulses.
6. Membrane potential is present only in nerve cells.
a) True
b) False
Explanation: A membrane potential of -70 mV is present in neurons. However this phenomena is not specific to neurons, membrane potential exists in other types of cells as well from anywhere between -15 to -100 mV.
7. Which of the following exists in nerve and muscle cells?
a) resting potential
b) membrane potential
c) potassium equilibrium potential
d) sodium equilibrium potential
Explanation: Nerve and muscle cells are the only excitable cells in the body; the potential difference that exists between extracellular and intracellular environments is termed as resting potential. However in other cells this voltage is termed as membrane potential.
8. On which of the following organisms, the research on nerve cells was first carried out?
a) Drosophila melanogaster
b) Grasshopper
c) Giant squid
d) Octopus
Explanation: The first research on action potential and nerve impulses was carried on the axons of giant squid in the late 1940s and early 1950s by Alan Hodgkin, Andrew Huxley, and Bernard Katz.
9. Depolarization is when ___________ ions flow inside the neuron’s membrane.
a) Potassium
b) Sodium
c) Chloride
d) Magnesium
Explanation: Depolarization is the flow of sodium ions into the membrane. These are positively charged and reduce the polarity of a cell with respect to external environment and are therefore cause depolarization
10. A neuron fires when _____________________
a) action potential is achieved
b) apoptosis is induced
c) re-stimulation occurs
d) stimulation ceases
Explanation: When the external stimulation is strong enough to reach the threshold value which is around -50 mV, the action potential is generated, and firing of the neurons occurs. This is actually the response to stimulus.