Suppose there is a di-allelic gene in the population with alleles A and a. Let the genotype code represent the number of A alleles in a person's genotype at the gene. So, Genotype Code 0 means aa genotype, etc. Further, suppose there is a quantitative trait whose mean values and standard deviations are determined by the genotypes. Specifically: Genotype Code 0 mean: -3.6 Genotype Code 1 mean: 0.00434 Genotype Code 2 mean: 4.09 Genotype Code 0 sd: 0.806 Genotype Code 1 sd: 0.412 Genotype Code 2 sd: 1.06, where sd means standard deviation. If an individual has phenotype value 1.44, what do you think is their underlying genotype code

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: