The answer is spicules. These
sharp-pointed structures are formed from calcium carbonate skeleton of
the organisms. They can also be formed from silica. They can be big (megascleres),
or microscopic (microscleres). Also dependent on the number of axis on the spicules, they are classified as monoaxon,
triaxon or polyaxon.
Answer:
When a molecule moves down its concentration gradient is it participating in passive transport; moving up the concentration gradient requires energy making it Answer:active transport
Answer:
Like all other cellular membranes, the plasma membrane consists of both lipids and proteins. The fundamental structure of the membrane is the phospholipid bilayer, which forms a stable barrier between two aqueous compartments.
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