How is a dichotomous key used?
the organism is compared to paired pictures of organisms until a match is found in the key.
the organism’s dna is sequenced and compared to the dna sequences that are listed in the dichotomous key.
observable characteristics of the organism are checked through a sequence of two-part steps until an identification is listed in the key.
observable characteristics of the organism are listed in a group and compared to different groups of observable characteristics listed in the key.

Four different thermometers were used to measure the temperature of a sample of pure boiling water. the measurements are recorded in the table below. thermometer temperature reading 1 temperature reading 2 temperature reading 3 w 100.1°c 99.9°c 96.9°c x 100.4°c 102.3°c 101.4°c y 90.0°c 95.2°c 98.6°c z 90.8°c 90.6°c 90.7°c the actual boiling point of pure water is 100.0°c. what can be concluded from the data about the reliability and validity of the thermometers?

The tubes transporting minerals and water upward are called ?

Which of the following statements is true about the relationship between genetic variation and natural selection? a. genetic variation must be present in a population before natural selection can act on it. b. genetic variation arises in a population as a result of natural selection. c. natural selection can act on a population whether there is genetic variation within the population or not. d. after natural selection acts on a population, the amount of genetic variation in the population always increases.