Agene family that codes for various hormone receptors has been accumulating nucleotide ubstitutions at a rate of 0.4 per million years. on average, there have been 60 substitutions between the common ancestor of this gene family and each of the various living forms of this gene. based on these figures, this hormone receptor gene family likely originatedmillion years ago. a. 15 b. 24 c. 75 d. 150 e. 300

Which of the following structures is not found in both plant and animal cells? a) chloroplast b) cytoskeleton c) ribosomes d) mitochondria

On a recent expedition to a remote region of northern canada, scientists uncovered skeletal remains from about 100,000 years ago. surprisingly, all the skeletal remains, which included many species from differing biological families and spanned about two thousand years, showed evidence of experiencing temperatures in excess of 1000 degrees fahrenheit (or 538 degrees celsius). which of the following, if true, best explains the apparent paradox between the cold environment and the evidence of the bones experiencing hot temperatures? (a) chemical changes that naturally occur during the process of decay in only one north canadian species produce the same evidence of the species' skeletons being exposed to hot temperatures as the expedition scientists found. (b) a little over 103,000 years ago, a large fire is known to have occurred in northern canada. (c) strong evidence exists that as early as 70,000 years ago, homo sapiens around the world relied heavily on fire to cook animals. (d) in the same expedition and in roughly the same layer of excavation, scientists found rudimentary wood cutting and hunting tools used by early humans.

Explain the source of radioactivity in uranium in earth’s crust by which it produces nuclear radiation