Answer:
recessive
Explanation:
a recessive allele is the gene donated by one parent which is present within the genotype, but is not expressed in the phenotype of the person's characteristics.
B and C are correct - A is incorrect as natural selection affects any generation of species. D is also incorrect as any species population change in an ecosystem inevitably affects another, even if it isn't a predator-prey relationship.
Answer: D. It yields chromosomes that contain both maternal and paternal DNA.
Explanation:
The recombination or crossing over is a genetic process. It takes place during the Prophase I of meiosis. The homologous pair align and held together by synapsis. This results in the mixture of genes combination formed from both parents that can be represented as a single chromosome.
If the recombination do not occur then each chromosome will be either 100% maternal or paternal. Thus recombination assures the recombinant chromosomes which consists of genetic material from both parents. Thus the genetic diversity of offspring increases.
Answer:
The correct answer is D) short-lived plasma cells that secrete antibodies for the antigen
Explanation:
Each B lymphocyte has an antigen receptor (BCR: B cell receptor), a surface immunoglobulin (IgM or IgD), that binds to specific domains of the antigen called antigenic determinants or epitopes. Only B lymphocytes with a high antibody affinity for the antigen, and which are capable of processing and presenting it, will be positively selected. In this contact between the two cells, an exchange of chemical signals takes place that leads to the activation, clonal proliferation and differentiation of B cells into two sister subclones: one of antibody-secreting plasma cells, and the other of memory primed B cells. Therefore, only these last positively selected B lymphocytes will survive, proliferate and differentiate into plasma cells, synthesizing and secreting antibodies of a single isotypic class, with a unique specificity and high affinity, improving the ability to adhere to the antigen and, thus , neutralize and destroy pathogens.
