Muscle tetany arises from
i) Hyperpolarization of nerve cell due to increased concentration of potassium ions inside the cell.
ii) Decreased activity of sodium gates due to increased concentration of calcium ions in extracellular fluid.
iii) Depolarization of nerve fiber due to sudden influx of sodium ions inside the nerve cell.
iv) Decrease in threshold potential of stimulus due to decreased calcium level.
i) Breakdown of glucose in cytosol.
ii) Formation of glucose using light energy.
iii) Degradation of glucose to form new organic compounds.
iv) Formation of glucose from organic compounds.
With respect to amino acids, which of the following is correct?
i) Tyrosine is a hydrophobic amino acids, and is usually found deep inside a globular protein.
ii) Glycine is an asymmetric amino acid because it contains two different groups – amino and carboxylic group.
iii) Alanine is non-polar amino acid with ethyl as the characteristic R group.
iv) Tryptophan is a complex aromatic amino acid which is precursor of T3 and T4..
Which of the following is true about human heart?
a) SA node produces rhythmic contraction of only atrial myocardial fibers by spontaneous discharge, while AV node discharges independently with same frequency for contraction of ventricular myocardial fibers.
b) If heart is isolated and kept in distilled water, it will show continuous contractions because SA node is autogenically excited repeatedly.
c) Human heart does not show fatigue in normal person even if it is contracting from the 1st month of intrauterine life.
d) Pumping action of heart helps in venous return of the blood from the peripheral tissues.