The sickle-cell allele is pleiotropic (that is, it affects more than one phenotypic trait). specifically, this allele affects oxygen delivery to tissues and affects one's susceptibility to malaria. heterozygous individuals who have one normal and one sickle-cell allele have a phenotype that has both costs and benefits. the cost: under conditions of low atmospheric oxygen availability, individuals heterozygous for this allele can experience life-threatening sickle-cell "crises." the benefit: such individuals are less susceptible to malaria. thus, pleiotropic genes/alleles reveal that

The diagram below represents a marine food web and a process that can harm the human population. each circle represents an organism and the smaller dots inside them represent a toxic substance. what is being represented and how does it harm the population? the diagram represents biological half-life, in which toxins build up in organisms higher up on the food chain, and this can negatively impact humans who consume the organisms and the toxic substance. the diagram represents biomagnification, in which toxins build up in organisms higher up on the food chain, and this can negatively impact humans who consume the organisms and the toxic substance. the diagram represents the process by which different organisms prey upon each other; this can impact the human population by reducing the number of organisms that do not contain the toxin. the diagram represents the way that toxins are metabolized by living organisms, with those at greater trophic levels able to metabolize more efficiently than those at lower levels. this means that those at higher tropic levels are safer for humans to consume compared to the organisms at lower trophic levels.

Can bacteria reproduce in a way such that when you start out with two bacteria, you get five bacteria? why or why not? * a. yes, because bacteria reproduce sexually, and can produce any number of offspring, just as humans do. b. no, because bacteria grow at an exponential rate. c. no, because when bacteria reproduce, they split into two parts, and two bacteria splitting would result in four bacteria.

Which zone within the open-ocean zone is home to the most organisms? deep zone surface zone intertidal zone transition zone