How does pressure in the astronaut’s space suit help the body work? A The suit forces blood to certain parts of the body to counteract the absence of gravity. B The suit acts as an external pacemaker to regulate the heartbeat. C The suit regulates gas exchange between the oxygen pack and the astronaut. D The suit monitors the amount of O2 to CO2 in the blood.

straight probes are used primarily for measuring flow as it is approaching the test area. its geometry allows the probe to be mounted so that it is in the direct line of airflow.

the oldest known insects are believed to live around 400 millions ago as suggested by the fossil records.   some plants having woody stems also evolved during this time.

after the evolution of insects the first four legged species or the tetrapods evolved in shallow freshwater habitats from the intermediate species approximately 397 million years ago. the tetrapods went on conquering the land giving rise to amphibians, reptiles, mammals and birds.

the major split in tetrapods first occurred 340 million years ago branching off from amphibians.

363 million years ago when the carboniferous period began the insects started roaming on land and taking flights, following which the four limbed tetrapods adapted in the terrestrial habitat.