What is true about the heterozygous sickle-cell (HbA HbS) condition?
A: sickle-cell anemia is not expressed
B: sickle-cell anemia is expressed under conditions of oxygen deficiency
C: sickle-cell anemia is apparent in men
D: none of the above

Describe characteristics of a good respitory surface

The human body needs energy in order to carry out life processes such as breathing. where does the body get this energy? a. from eating food b. from learning about new things c. from lying in the sun d. from sleeping

Some species of wasps are social. the queen starts a colony from scratch each spring. she builds a small nest, and lays and raises a group of female workers. the workers enlarge the nest while the queen continues to lay eggs. unfertilized eggs become males that mate with newly hatched females. all of the wasps except the newly fertilized females die by the summer. which best describes this behavior? a)it is beneficial only to the males that do not fertilize eggs. b)it is beneficial only to the female workers that are not fertilized. c)it is beneficial to each one of the individual colony members. d)it is beneficial to the whole species, but not to all of the individual members.