The first line of defence (or outside defence system) includes physical and chemical barriers that are always ready and prepared to defend the body from infection. These include your skin, tears, mucus, cilia, stomach acid, urine flow, 'friendly' bacteria and white blood cells called neutrophils.
Answer: Atoms constitute the fundamental units of matter, and are a constituent of each element. In large part, the mass of an atom is determined by its positively charged protons and neutral neutrons.
Explanation:
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Africa is the only place where giraffes live in the wild
Phospholipids (lipid bilayer)
