The population in south africa is more prone to sickle cell anemia (genotype “ss”). people with genotype “ss” survive only up to 14-15 years of age. people with “ss” are prone to malaria because the parasite resides inside their rbcs. people with genotype "ss" are resistant to malaria because the parasite cannot reside inside their rbcs, and they can live a normal life (without sickle cell anemia). what kind of evolutionary force must be operative in south africa?

the level of progesterone is low at the pre-ovulatory phase of the cycle but it gradually increases and the levels are high at the luteal phase. if pregnancy occurs, the level of progesterone will be high throughout the pregnancy.

if egg is fertilized and the mother gets pregnant, progesterone starts preparing the uterus for the implantation. it starts building up the lining of uterus and make it hostile of the period of pregnancy.

succession returns a disturbed

ecosystem to a more stable state. this is also classified into two (2) types:

primary succession and secondary succession. the primary succession arises when

a new land is transformed and a bare rock has been exposed providing an environment

that can be occupied for the first time. while, secondary succession occurs

when a previously occupied environment was disturbed that kills much of all its

community

explanation: