Systematics is the study of the units of biodiversity. Systematics differs from ecology in that the latter is concerned with the interactions of individuals (and therefore species) in a particular time.
Answer:
Plants need a rigid structure. Animal cells have flexible cell membranes. So animal cells can have a variety of shapes, but plant cells can not, they have to take the shape of their cell walls. Both plant and animal cells are eukaryotic, so they contain membrane-bound organelles like the nucleus and mitochondria.
It is probably the l<span>amellae.
The lamellae are sheets of bony matrix. This bony matrix is produced by o</span>steoblasts, which are cells that synthesise collagen<span> and specialised proteins like </span>osteocalcin<span> and </span>osteopontin. These are then the most important constituents of the bony matrix.
Environments are always changing so organisms need to adapt to survive. The organisms that survive are the ones that are fit to live in that environment, which is where survival of the fittest comes into play.
Archaea bacteria live and thrive in extreme environments (extreme salt, extreme temperature), whereas eubacteria live best in more 'normal' environments that are closer to what we (humans) are used to.
