A)A chromosome is a long continuous strand of DNA
The tree may erode or rot in the water or the remains of the tree will sink into the soil
The troposphere is the first layer above the surface and contains half of the Earth's atmosphere. This is where weather occurs.
Infection is the invasion of an organism's body tissues by disease-causing agents, their multiplication, and the reaction of host tissues to these organisms and the toxins they produce. Infectious disease, also known as transmissible disease or communicable disease, is illness resulting from an infection.