The answer is true for this
The body's first line of defense is actually the non-specific immune system which is also called innate immunity.
Innate immunity employs both physical and chemical barriers that form the first line of defense. These include:
1. The intact skin. The skin is made up of keratin in its outermost layer. Keratin makes skin tough and resistant and pathogens usually cannot penetrate unless the skin is broken.
2. The mucus membrane. This is a thin membrane that forms a protective lining inside many organs and other parts of the body such as the trachea. Mucus produced by the membrane traps bacteria and other harmful particle which are then expelled from the body.
3. Tears. Tears from our eyes contain lysozyme, a chemical that kills bacteria.
If the pathogen gets through or evades these types of defenses, then it is dealt with by the second line of defense which is called specific immunity or acquired immunity. It is here that white blood cells namely the B lymphocytes and T lymphocytes attack, kill or neutralize pathogens.
Answer:(B) decrease protein production
Explanation: nitrogen gas in the atmosphere is the source of nitrogen which is useful to plants.
In the nitrogen cycle, nitrogen gas is converted to it's compounds and then back to it's gas form.
The nitrogenous cycle involves fixation, mineralization, nitrification and denitrification .
In the first three states, nitrogen undergoes changes into a state where it can be absorbed by plants.
In denitrification,nitrates (useful form of nitrogen) are converted into gaseous nitrogen.organisms involved in this process are called denitrifying bacteria eg Pseudomonads sp.
Nitrogen is an important element.
It is useful for the production of protein, DNA, RNA and chlorophyll.
When it is deficient in the soil,it affects the synthesis of proteins and yellowing of leaves due to decrease in chlorophyll
Darwin went to the continents of Africa and South America, wherein both of them have a tropical grassland/Savanna biome. The grasslands in these continents gave him a chance to notice that species do vary globally. He observed the similarities between the different large, flightless birds species–rheas, ostriches, and emu.
Answer:
b.
Explanation:
food and water can be obtained by either hunting or farming but small houses more people is a common problem in bigger countries due to new infrastructural ideas.
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