D is for dichotomous key;dichotomous key is a special identification that use a series of paired characteristics that leads to the idenification of an organism,object or material .
O is for ozone layer ;ozone layer is a layer in the earths stratosphere at an attitude to 6.2 miles. Which absorbs most of the ultraviolet radiation reaching the earth from the sun .
T is for thermometer; thermometer is a tool that takes the temperature of the outside weather or takes someone temperature to see if they have a fever .
V is for vascular ;vascular is plants that have well developed systems for transporting water and food . They have roots,stems,and leaves . ( largest group in the plant kingdom )