fine canals in bone tissue that link lacunae.
the loss of water vapour from the aerial parts of a plant through stomata or lenticels.
a tough substance made from a modified polysaccharide that contains nitrogen. It is the main...
a cluster of capillaries situated inside Bowman's capsule in the nephron.
a ranking system.
mass extinction event of 250 million years ago, in which about 90% of all species on Earth died...