Because an antibody is "made" relative to the antigen, but kept at low levels when you are exposed the first time ("primary immune response"). The second time you're exposed to the same antigen, memory cells recognize it and the body produces a high level of antibodies, and the level of antibodies usually remains higher for a longer time ("secondary immune response"). This is your basic immune response (primary and secondary).
This explains exactly why vaccines are effective to extremely effective.
cell wall
the main difference between animal cell and plant cell is in existing of cell wall on plant cell and existing of centriols in animal cell large vacules in plant cell ...
The forearm of birds, reptiles, and humans illustrates a homologous body structure.
- Similar physical characteristics found in species with a shared origin are known as homologous structures, although these characteristics have entirely different biological purposes.
- The limbs of humans, cats, whales, and bats are examples of homologous structures.
- All of these structures—arm, leg, flipper, and wing—are supported by the same type of bone structure.
- The arms of a person and the wings of a bat are excellent examples of homologous structures. Because both bats and people are mammals, they have a common ancestor.
- Even though they appear considerably different from one another from the outside, a bat's wing and a human arm have remarkably comparable internal bone structures.
- Wings help bats fly, whereas arms enable human interaction with their environment. The wing and the arm also have various purposes.
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Answer:
examples can be kelp and seaweed with their multi-cellular composition
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Answer:
There are over 30 phyla dedicated to invertebrates. Major invertebrate phyla that you should know include porifera, cnidaria, platyhelminthes, nematoda, mollusca, annelida, arthropoda, and echinodermata
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