NEED HELP! Sickle cell disease is lethal, usually killing its victims before they reach maturity and can reproduce. According to the theory of natural selection, the sickle cell gene should not remain in the population. How do scientists explain its prevalence in certain regions?​

The model illustrates a process by which a substance is taken up by a cell

The current thought on the structure of the cell membrane is: a. a static phosphate sandwich of lipids b. a fluid-mosaic of phospholipids and proteins c. a bilayer of proteins with static lipid molecules d. an impermeable bilayer of protein molecules e. a static and permeable phospholipid single layer

The embryos of a bird, a reptile, and a mammal are similar in appearance. how does comparing the physical appearance of embryos of different species support the theory of evolution? a. it shows that these organisms share a common ancestor. b. it provides evidence that these organisms eat the same foods.c. it shows that these organisms share the same habitat.d. it provides evidence that these organisms suffered a genetic mutation.