The defense system of the human body is made up of entire organs and vessel systems like the lymph vessels, but also of individual cells and proteins. The inner and outer surfaces of the body are the first barriers against pathogens (germs). These surfaces include the skin and all mucous membranes, which form a kind of mechanical protective wall.
Several things support this protective wall:
<span><span>- The body’s own antibacterial substances can disable different pathogens from the environment at an early stage. A certain enzyme found in saliva, the airways and tear fluid destroys the cell walls of bacteria.
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- Many pathogens that are breathed in get stuck to mucus in the bronchi and are then moved out of the airways by hair-like structures called cilia.
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- Most pathogens that enter the body together with food are usually stopped by stomach acid.
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- Normal flora, harmless bacteria that reside on the skin and many mucous membranes in the body, also help to protect the body.</span></span>
The cough and sneeze reflex can also help to remove pathogens.
Hope this helps (:
Three scientists are credited with the development of cell theory. Matthias Schleiden observed that all plants were made of cells; Theodor Schwann observed that all animals were also made of cells; and Rudolf Virchow observed that cells only come from other cells.
Answer – D. RNA
Like proteins, Ribonucleic acid is another kind of organic molecule that also acts as a catalyst for chemical reactions. Asides acting a catalyst for chemical reactions, proteins have a wide variety of functions that they perform in in living cells.
Answer:
A. Rivers
Explanation:
because most of the water comes from two big rivers
Answer:
A. true
B. false
C. true
D. true
E. true
Explanation:
A. it works kind of like a door lock they have a specific alignment in which it can fit only the complimentary substrates.
B. their shape isn't affected by the reaction. however their structure can be affected due to constant reuse.
C. they are biological catalysts that break down bonds which helps in making digestion faster.
D. for example: digestion, neutralization...
E. pH can affect the enzyme's shape which will slow it down, temperature can help the enzyme work faster however if it gets too high it will affect the enzyme's shape.
