Answer:
The first yellow fever outbreaks in the United States occurred in late 1690s. Nearly 100 years later, in the late summer of 1793, refugees from a yellow fever epidemic in the Caribbean fled to Philadelphia. Within weeks, people throughout the city were experiencing symptoms.
Chargaff's rule states that A (adenine) only bonds with T (thymine) and C (cytosine) only bonds with G (guanine) in a DNA strand. Since DNA replication is semi-conservative, this complementary base pairing allows two of the DNA molecules to be identical to each other as they have the same base sequence. The new strands made are complementary to their template strands and also identical to the other template. Complementary base pairing is important in the conservation of the base sequence of DNA because adenine always pairs with thymine, while guanine pairs up with cytosine. All in all, complementary base pairing has a huge role in the conservation of the base sequence of DNA.
Answer:
El Niño is defined as an unusual weather pattern seen in the Pacific Ocean. In this weather unusual winds allows the surface water to get warm from the equator to move east, that is toward Central and South America.
So, El Niño affects wind shear, in which air current present in lower altitude moves to different direction from winds higher in the atmosphere and affects weather patterns. such as El Niño is responsble for more rain in South and Central America and in the United States.
Answer is B. Porifera
Members of the phylum porifera includes animals which lack tissues. These animals are also called sponges. These are the simplest multicellular animals. Even though they are multicellular, they do not have any tissues or organs. They have cellular level of body organization. Sponges are aquatic animals and water plays a major role in the feeding, exchange of gases and as well as excretion.