The heart of an embryo starts to pump blood by the .

Emerging from the placenta is the umbilical vein, which carries oxygen-rich blood from the mother to the fetal inferior vena cava via the ductus venosus to the heart that pumps it into fetal circulation.

1. true.2. true.3. true.4. false.5. true.the concept of darwin's theory of evolution involves the idea that there are limited resources in a given living environment and that the organisms which live within have variations in their genetic make up due to random mating. the ones with beneficial genetic variations can express certain traits which give them an upper hand in surviving and reproducing in the said environment compared to ones who may have a more disadvantageous variation in traits. over time, the organisms with an upper hand will survive and reproduce more frequently and pass on their beneficial genes while the others die. the result is evolution, where we observe (usually, but not always) eventually, phenotypic distinct changes.