QUES: During the process of meiotic cell division, an event called genetic recombination or crossing-over can sometimes occur, in which a length of DNA on one chromatid is swapped with a length of DNA on the corresponding sister chromatid. This has no effect if the alleles on the chromatids are the same, but results in reassortment of otherwise linked alleles if they are different.:5.5 The Mendelian principle of independent assortment asserts that each of a parent's two genes for each trait will sort independently into gametes; which allele an organism inherits for one trait is unrelated to which allele it inherits for another trait. This is in fact only true for genes that do not reside on the same chromosome, or are located very far from one another on the same chromosome. The closer two genes lie on the same chromosome, the more closely they will be associated in gametes and the more often they will appear together; genes that are very close are essentially never separated because it is extremely unlikely that a crossover point will occur between them. This is known as genetic linkage.

If the alleles on the chromatids are different, what effect arises from genetic recombination?
What is the answer?
ANS: reassortment of otherwise linked alleles
QUES: Another solution to the problem of causality-based temporal paradoxes is that such paradoxes cannot arise simply because they have not arisen. As illustrated in numerous works of fiction, free will either ceases to exist in the past or the outcomes of such decisions are predetermined. As such, it would not be possible to enact the grandfather paradox because it is a historical fact that your grandfather was not killed before his child (your parent) was conceived. This view doesn't simply hold that history is an unchangeable constant, but that any change made by a hypothetical future time traveler would already have happened in his or her past, resulting in the reality that the traveler moves from. More elaboration on this view can be found in the Novikov self-consistency principle.

In several works of fiction, what ceases to exist in the past which causes decisions not to arise?
What is the answer?
ANS: unanswerable
QUES: The South American highlands were a center of early agriculture. Genetic testing of the wide variety of cultivars and wild species suggests that the potato has a single origin in the area of southern Peru, from a species in the Solanum brevicaule complex. Over 99% of all modern cultivated potatoes worldwide are descendants of a subspecies indigenous to south-central Chile, Solanum tuberosum ssp. tuberosum, where it was cultivated as long as 10,000 years ago. According to George Raudzens, "It is clear that in pre-Columbian times some groups struggled to survive and often suffered food shortages and famines, while others enjoyed a varied and substantial diet." The persistent drought around 850 AD coincided with the collapse of Classic Maya civilization, and the famine of One Rabbit (AD 1454) was a major catastrophe in Mexico.

Where did the potato originate?
What is the answer?
ANS:
area of southern Peru