The correct answer is the second option. Animals have two major types: vertebrates and invertebrates. Vertebrates are animals that have backbone while the invertebrates do not have one. Examples for vertebrates are birds and mammals while the latter are insects and squid.
The structure of the skin is an effective barrier against bacteria. The multiple layers of epidermis, while can be invaded by foreign organisms, has a high turnover rate which means it is constantly shedding, therefore even the bacteria is shed protecting the body. Lastly, the skin's lipids maintain an acidic pH which slows and stops growth and replication of bacteria.
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An invasive species is a species that is not native to a specific location, and that has a tendency to spread to a degree believed to cause damage to the environment, human economy or human health.
Answer:
Oxygen is used to break down sugar and sugars release energy
