Awoman with long hair is a suspect in a burglary case. at the crime scene, several long hairs were found attached to a broken lock of the safe. the police obtain a warrant and request a sample of 25 to 50 hairs from this woman. they tell the woman it is important that they pull the hairs from her head rather than to merely cut the hairs. the police suspect that the woman was stealing to support a drug habit.
a. why is it important that the police pull the hairs from her head rather than cut her hair? b. why is it necessary to obtain 25 to 50 hairs from this woman? c. the woman denies that she is currently taking drugs and states that she stopped using drugs a year ago. explain how the police can determine if the woman has been off drugs for over one year. d. suppose the hairs of the woman match the hairs found at the crime scene. why does this not necessarily prove that she was the guilty party?

fertilization, pictured in figure 24.23a is the process in which gametes (an egg and sperm) fuse to form a zygote. the egg and sperm each contain one set of chromosomes. to ensure that the offspring has only one complete diploid set of chromosomes, only one sperm must fuse with one egg. in mammals, the egg is protected by a layer of extracellular matrix consisting mainly of glycoproteins called the zona pellucida. when a sperm binds to the zona pellucida, a series of biochemical events, called the acrosomal reactions, take place. in placental mammals, the acrosome contains digestive enzymes that initiate the degradation of the glycoprotein matrix protecting the egg and allowing the sperm plasma membrane to fuse with the egg plasma membrane, as illustrated in figure 24.23b. the fusion of these two membranes creates an opening through which the sperm nucleus is transferred into the ovum. the nuclear membranes of the egg and sperm break down and the two haploid genomes condense to form a diploid genome.

explanation: