Genes and phenotypic adaptation work together to produce a biochemical difference between human groups in the ability to digest large amounts of milk. This is an adaptive advantage when
A. herding societies shift to a sedentary agricultural lifestyle.
B. mothers cannot wean their children from breast milk after they turn one year old.
C. other foods are scarce and milk is available, as it is in herding societies.
D. there is not enough lactose in the diet.
E. lactase, the enzyme that breaks down lactose, is not produced in enough quantities to keep up with dietary intake.
Question 2
What is a phenotypic adaptation, and what makes it possible?
A. It is a genotypic adaptation that is expressed in the phenotype. It is made possible by the close relationship between our manifest biology and our genes.
B. It occurs when genetic changes take place during an individual's lifetime. It is made possible by human genetic plasticity, our ability to change in response to the environments we encounter as we grow.
C. It is a phenotypic adaptation made possible by culture's power over biology.
D. It happens when adaptive changes occur during an individual's lifetime. It is made possible by human biological plasticity, our ability to change in response to the environments we encounter as we grow.
E. It is a biological adaptation that occurs during an individual's lifetime and, if critical enough to survival, will actually modify the genotype.
Electron-micrograph of human sperm.
Human cavity
A highly simplified view of the overall plan of the human body.
Genes are composed of a sequence of nucleotides in a DNA molecule
G-banded karyotype of a normal human male
Analysis of double-mutant phenotypes to find order of genes in developmental pathways