  We study the frustrated dimer-plaquette quantum spin chain for ferromagnetic
dimer bonds. This quantum system undergoes a series of first-order ground-state
phase transitions driven by frustration or by a magnetic field. We find that
the different nature of the ground-state phases has a strong influence on the
magnetization curve as well as the low-temperature thermodynamics. In
particular, the magnetization curve exhibits plateaus and jumps, the number of
which depends on the strength of frustration. The temperature dependence of the
susceptibility may either show activated spin-gap behaviour for small
frustration or Curie like paramagnetic behaviour for strong frustration.
