21. on first attachment is secondary succession
22. is the degree of variation of life....
genetic, species or ecosystem within a specific area, system or planet
23. the last one is wrong = )
Answer:
React on cell surfaces, catalyze reactions.
Answer:
1-Viruses also lack the properties of living things: They have no energy metabolism, they do not grow, they produce no waste products, and they do not respond to stimuli.
2-They also don't reproduce independently but must replicate by invading living cells.
