Which statement is true about a person's chromosomes? 1: they are all identical

2: their sister chromatids are joined at centrosomes

3: they are arranged in homologous groups of three

4: they are long chains of DNA

Two true-breeding pea plants were crossed. one parent is round, terminal, violet, constricted, while the other expresses the respective contrasting phenotypes of wrinkled, axial, white, full. the four pairs of contrasting traits are controlled by four genes, each located on a separate chromosome. in the f1 only round, axial, violet, and full were expressed. in the f2, all possible combinations of these traits were expressed in ratios consistent with mendelian inheritance. (a) what conclusion about the inheritance of the traits can be drawn based on the f1 results? (b) in the f2 results, which phenotype appeared most frequently? what mathematical expression predicts the probability of occurrence of this phenotype? (c) which f2 phenotype is expected to occur least frequently? what mathematical expression predicts this probability? (d) in the f2 generation, how often is either of the p1 phenotypes likely to occur? express your answer as a fraction (example: 3/16).

Two male mice, which we will call male a and male b, are both phenotypically normal. male a was from a litter that contained half phenotypically normal mice and half dwarf mice. the mother of male a was known to be homozygous for the normal igf2 allele. male b was from a litter of eight mice that were all phenotypically normal. the parents of male b were a phenotypically normal male and a dwarf female. male a and male b were put into a cage with two female mice that we will call female a and female b. female a is a dwarf and female b is phenotypically normal. the parents of these two females were unknown, although it was known that they were from the same litter. the mice were allowed to mate with each other, and the following data were obtained: female a gave birth to three dwarf babies and four normal babies. female b gave birth to four normal babies and two dwarf babies. which male(s)mated with female a and female b? male a with both females male a with female b, and male b with female a male a with female a, and male b with female b could not be determined male b with both females

This is an active transport mechanism by which cells pump sodium and potassium ions against the concentration gradient