Crime-scene work often involves obtaining a DNA sample from a drop of blood to help identify persons who may have been involved. Frequently, the size of the DNA sample is extremely small, too small for easy analysis. Which of the following laboratory procedures could criminologists use to amplify the amount of DNA present? a
Cloning and gel electrophoresis

b
Cloning and polymerase chain reaction (PCR)

c
DNA splicing and polymerase chain reaction (PCR)

d
Vector amplification and DNA splicing

b

explanation:

oxygen +1 most likely

the atmospheric gas that forms a mild acid when dissolved in water is called carbon dioxide. the correct answer is a. 2.) chemical weathering would cause an inscription on a marble headstone to become harder and harder to read over time.

answer: ice crystals in air

the water from the water body or another source of water gets evaporated as water vapor as an effect of heat on water. these water vapor rises in the upper layers of the earth atmosphere under high atmospheric pressure. the atmospheric pressure of these water molecules starts to decrease due to the effect of cold air. the invisible water vapor condenses into visible water droplets and ice crystals.these ice crystals and water droplets being less denser than the surrounding air floats on air as clouds.