Two brothers have X‑linked red–green colorblind vision, and their parents have normal color vision. The first brother's karyotype is 47,XXY (Klinefelter syndrome), and the second brother's karyotype is 46,XY. In which parent and in what cell division phase did the first brother's chromosomal nondisjunction occur? Assume no recombination.

The answer is mother in meiosis II

Explanation:

nondisjunction can be defined as the failure of the segregation of the child chromosomes in meiosis I and meiosis II resulting in gametogenes. This results in abnormal gametes with some chromosomal imbalance being formed and subsequent fertilization of these gametes results in a generation of abnormal individuals.

According to exercise, red-green color blindness follows an X-linked recessive pattern and the phenotype is only expressed. the father cannot bring the possibility of color blindness to his children, and the nondisjunction, defined earlier, cannot occur in either meiosis I or meiosis II. As a conclusion we can say that it may have a place in meiosis I or meiosis II corresponding to the mother and although the mother's condition may be normal, the first child would be compromised with color blindness, therefore, the mother is the carrier.

the answers are a and c

the correct answer is - d. china has a large and growing population.

the fact that china has a large (the biggest) population, and it is still growing, doesn't hinder the agriculture production in the country. in fact, it can for increased production in the agriculture, since there's more labor force, as well the sheer mass of people produces lots of scientists that come up with new inventions as to how to improve this sector. nice example is the inner mongolia region in china, in general dominated by the gobi desert, but few scientist came up with a nice idea as to how to make the region productive by using plants that are very resistant to droughts, so lots of people have been employed, and the region is becoming greener and greener each year, and the production of food in this region is also increasing.