Assertion: cell wall's shape | /r/CapableOf | allow oxygen exchange
Facets:
value: at a constant rate
type: MANNER
Source sentences:
text: The biconcave shape of the cell allows oxygen exchange at a constant rate over the largest possible area.
text: The cells are small and highly flexible, which helps them squeeze through even the smallest blood vessels, and their biconcave shape allows for oxygen exchange at a constant rate.