Which of the following is an example of a role programmed cell death plays in maintaining homeostasis?
1) preventing crossover during meiosis
2) preventing self-fertilization in plants
3) promoting conjugation of dna in bacteria
4) promoting tissue growth in body cells

Why are scientists concerned about the depletion of the ozone levels in the stratosphere?

Amino acids contain the elements carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur. of the 20 amino acids found in humans, 11 are called "nonessential" because they can be manufactured by the body when needed. which elements in these 11 amino acids are commonly obtained from the metabolism of sugar molecules?

What molecules will be best used to compare different species with the exact same sequence of amino acids? why would two species have the same protein even if the molecules in question is different? (hint: transcription to translation to protein).