Which of these body systems has cells that attach to each other to form a leak-proof barrier? Select one:

Urinary system.

Reproductive system.

Respiratory system.

Endocrine system.

Which term refers to the total dollar value of the goods and services produced in a country in a year?

Ectocarpene is a volatile, sperm cell-attracting material released by the eggs of the seaweed ectocarpus siliculosus. its constitution is all the double bonds are cis, and the absolute configuration of the chirality center is s. draw a stereochemically accurate representation of ectocarpene.

How much time has elapsed from the very beginning of "the memior of the conquistador bernal diaz del castillo" to the end? a. castillo's whole life b. a quarter of an hour c. a few weeks d. a decade