Two remnants of fetal structures are observable in the adult heart- the ligamentum arteriosum and the fossa ovalis. the fetal heart structures are called the ductus arteriosus and the foramen ovale, respectively. what common purpose did they serve as functioning fetal structures? a. they allowed blood to bypass the non-functional fetal lungs. b. they supplied blood to the immature fetal heart muscle. c. they provided support the the delicate tissues of the developing heart. d. they received maternal blood from the umbilical cord.

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explanation:

plate tectonics and volcanic euptions

over time, plate tectonic processes cause continents to move to different positions on the globe.

for example, britain was near to the equator 300 million years ago, and therefore was hotter than it is today. for further details look at our climate through time poster or online map.

the movement of the plates also causes volcanoes and mountains to form and these too can contribute to a change in climate.

mountain ranges formed by plate tectonics. large mountain chains can influence the circulation of air around the globe, and consequently influence the climate.   warm air might be deflected somewhere cooler by the mountains.

the second type of galaxy is called a barred spiral, which has a thing called a bar straddling the nucleus

answerhomologous structures;