You would expect leptin deficient mice to be . A. Have normal appetite and body mass.
B. Obese and overeating.
C. Same as ghrelin-deficient mice.
D. Thin and anorexic.

Option B.

Obese and over eating

Explanation:

A leptin deficient move would be obese and overeating because leptin is an hormone produced by fat cells that decrease appetite and when it is deficient in the body,the body assumes that there is no enough fat in the body and it send signals for intense hunger and overeating or uncontrollable eating of food which result in accumulation of fats, there by resulting in obesity.

D In Prophase I the chromosomes crossover, in Prophase II they do not crossover

Explanation:

Meiosis is a type of cell division in which four daughter cells, which are genetically different from one another, are produced. The daughter cells have their chromosomal number reduced by half. Since, the meiotic process aims at producing haploid gametes, it occurs in a series of two-division steps viz: meiosis I and meiosis II.

Meiosis I involves the separation of homologous chromosomes into two daughter cells while the meiosis II involves separation of chromatids to make four daughter cells. One major difference between meiosis I and meiosis II is that in the PROPHASE of meiosis I, a unique process called CROSSING OVER occurs but does not occur in meiosis II (as seen in the attached image).