A concentration gradient can be described as a phenomenon by which molecules travels from an area which is highly concentrated to an area which has low concentrations of that molecule.
Answer No 2:
A molecule is said to be diffusing down a concentration gradient when molecule acquire the phenomenon of concentration gradient i.e move from higher concentration to lower concentration. This mechanism is also termed as passive transport. Active transport is the opposite of passive transport. In active transport, molecules move against the concentration gradient i.e from an area of lower concentration to an area of higher concentration.
Since it's a recessive disorder that means the presence of the dominant allele will overshadow the recessive if it's present. Two recessive alleles have to be present in order for the person to have the disorder.
