What structure is most important in forming the tetrads?
centromere
synaptonemal complex
chiasma
kinetochore

The correct answer will be option- synaptonemal complex.

Explanation:

The tetrad arrangement of the genetic material in an organism is mediated by a highly conserved structure known as the synaptonemal complex.  The synaptonemal complex is formed during the prophase I of the meiosis I which attaches the chromatin of the homologous chromosomes.

The synaptonemal complex is a proteinaceous structure which is formed by the two lateral ladders like elements with a central portion composed of the central element. The chromatin gets attached to the lateral elements while the central a portion bridge space between the two ladders thus help in the formation of the tetrad.

Thus, option- synaptonemal complex is the correct answer.

your answer is "the 1950's"

c) 50% there are four chromosomes. after crossing over, 2 of the four have been changed. that means any gamete has a 2 in 4 chance or 50% chance of receiving the mutated chromosome.