Which of these is a way that the sexual life cycle increases genetic variation in a species? 1. by allowing crossing over
2. by allowing an increase in cell number
3. by conserving chromosomal gene order
4. by decreasing mutation frequency

Which phrase is the best summary of the model shown? a. the transfer of the sun's energy through trophic levels b. a series of aerobic and anaerobic reactions c. a transformation of light energy into chemical energy d. the breakdown of food molecules

Approximately what wavelength of light is best absorbed by chlorophyll a

What is the difference between topsoil and clay?