Molecules on the outer surface of a microorganism act as _ ,which stimulate activity in the immune system. In _ ,circulating antibodies work with B cells to destroy the invaders. In _ ,macrophages and helper T cells are involved.
Answer choices:
Choose 1 for blank space #1: Phenotypes, mutagens, genotypes, or antigens
Choose 1 for blank space #2: cell-mediated immunity, humoral immunity, or non-specific immune response
Choose 1 for blank space #3: humoral immunity, cell-mediated immunity, or non-specific immune response

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:

this protocol provides a detailed procedure for nucleoprotein extraction from cultured cells and tissues in an efficient manner.

the correct answer is:

a population changes in response to a change in the environment.