Hypothesize one way that a diploid organism could have offspring that are 3n or 4n

Popypoidy mainly occurs in the plants when there is total non-disjunction of sister chromatids occurs during the meiosis of gametic cells. So as before the meiosis the number of chromosomes doubles and after meiosis every cell get half the number of chromosome so after segregation failure autopolyploidy occurs in plants.

Triploid condition can also be seen in animals when two sperms fertilize one ovum. So, in this case, the chromosome number reaches to 69(23+23+23) which means chromosome number become 3n.

the answer is lactic acid from anaerobic respiration. the acid in lactic acid is what creates sore and burning muscles. if you think about how acid burns that will give you a clue for questions like this.

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.