Heterozygotes at the sickle-cell locus produce both normal and abnormal (sickle-cell) hemoglobin (see concept 11.4). when hemoglobin molecules are packed into a heterozygote’s red blood cells, some cells receive relatively large quantities of abnormal hemoglobin, making these cells prone to sickling. in a short essay (approximately 100–150 words), explain how these molecular and cellular events lead to emergent properties at the individual and population levels of biological organization.

In an individual's molecular and cellular level, the heterozygote alleles are preferred over the homozygote alleles. In humans, the heterozygote alleles are found at a locus of beta polypeptide subunit of hemoglobin, while on the other hand, the homozygous alleles found at a similar locus are prone to sickle cell disease.  

The individuals carrying homozygous alleles exhibit sickle-shaped RBCs and they also possess low oxygen-carrying capacity, which ultimately results in brain, kidney, or heart failure. However, in the case of heterozygous alleles, the configurations of RBCs are of two kinds, that is, normal shaped and sickle-shaped. Thus, there are not enough sickle-shaped cells to result in the condition.  

The heterozygote alleles are resistant to malaria, thus, in tropical areas, where malaria is a prime issue the heterozygote alleles are preferred over the homozygote dominant alleles as they are vulnerable to the infection and over the homozygote recessive alleles who has sickle cell disease.  

i think it is true in my reasonment ..