Answer: is heterozygous
Explanation: A hybrid is heterozygous which means that it has one dominant gene and one recessive gene. A dominant gene is a type of gene which has the ability to express itself phenotypically either in a homozygous or a heterozygous state. A dominant gene masks the effect of a recessive gene. A recessive gene is a type of gene that lacks the ability to express itself in a heterozygous state. It can only express itself outwardly in a homozygous state. It's effect is masked by the dominant gene is a heterozygous state.
Most populations changed from mostly light colored to mostly dark colored in the 1800s. This relates to microevolution.
Answer:
1 - Malaria
2- Typhoid fever and Tuberculosis
Explanation:
In case of malaria, the causal microorganism is Plasmodium falciparum, which target red blood cells of host. In humans who have defective sickle cell allele, have abnomral shaped red blood cells. So microorganism does not able to attach to abnormal shaped RBCs thus humans having sickle cell allele are more resistant to death caused by malaria.
In cystic fibrosis, mutation on that gene which encodes a protein known as cystic fibrosis transmembrane conductance regulator (CFTR).
Normally Salmonella typhi (bacteria responsible for typhoid fever) enters into intestinal cells by attaching with CFTR receptor. Carriers of cystic fibrosis mutant gene, have abnormal CFTR thus reduced rate of entry of bacteria into carriers.
Normally Mycobacterium tuberculosis (bacteria responsible for tuberculosis) adds sulfate in its cell walls. In carriers of cystic fibrosis, arylsulfatase B activity is reduced which incorporates sulfate. Thus reduced arylsulfatase activity makes bacteria unable to add sulfate in its cell walls thus decreases their virulence to carriers of cystic fibrosis.
