Wavelength
It is the distance between successive crests of a wave, especially points in a soundwave or electromagnetic wave. Frequency is the rate at which the it is repeated over a particular period of time. Trough is the level at which the wave has the highest point. Crest on the other hand is the opposite of trough it is the lowest point of wave. The unit of frequency is the Hertz. It is the SI unit of frequency, equal to one cycle per second.
Answer:
Lead in
g of blood
grams
Explanation:
Given -
Amount of lead in human blood -
parts per million (ppm)
This is equivalent to
g of lead for each million grams of blood
Numerically, it can be represented as -

Lead in
g of blood
grams
Lead in
g of blood
grams
Metanephridia differ from protonephridia in that selective reabsorption of materials occurs via cells lining the tubules in protonephridia and via capillaries in metanephridia is true.
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What are the Metanephridia?</h3>
Metanephridia gather the liquid from the celomatic hollow space via a funnel-like shape known as nephrostome. The coelomic fluid enters the tubulus, water and vitamins are reabsorbed, and the metabolic waste inclusive of ammonia, urea, or uric acid is excreted.
The principal distinction among protonephridia and metanephridia is that protonephridia are a community of dead-give up tubules with out inner openings, while metanephridia are a kind of excretory glands with a ciliated funnel starting into the frame hollow space.
Read more about the protonephridia :
brainly.com/question/11072950
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