Human bone, muscle, and nerve cells all contain the same number of chromosomes with the same complement of genes. What enables these cells to perform specialized activities?

F The ability of some cells to remove unnecessary DNA Sequences

G The regulation of gene expression within each cell type

H The mutation of genes within each cell type

JThe use of different methods of cell division

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

Protein synthesis actually begins in the nucleus when transcribes a single gene on the dna molecule is copied. the process of copying this gene is called this copy is known as and contains the protein building instructions. this copy is sent out into the cytoplasm to the part of the cell known as the the of the ribosome will join together to form a functional ribosome when they attach to the mrna. as the mrna moves through the ribosome, the message is read by transfer rna brings the correct back to the ribosome. the amino acids are placed in the correct order and are hitched together by

Hurry which of these is true about index fossils? a) are very scarcely found b) used as guides in relative dating c) found in the youngest layer of the rock d) used as reference points in absolute dating