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11Biologically important metals can be divided into
……………….groups.
12……………………such as calcium , potassium….
13…………………………………are essential at low concentration ,
but many may be …………………….at high concentration such as
……………………,……………….
14……………………………..are not required
for metabolic activity
and are toxic at low concentration such as……………………..
15……………………..and……………………….are
poor
regulator
of
heavy metals.
16……………………….and fish
can regulate essential metals like
……………….and ………………
17Mercury
is
used
in………………………,
………………….,
………………………industries , ……………………..paints
etc but after
discovering the dangers of mercury to human lives , it has been
………………….by other substances.
18A common way to remove mercury and other metals from
bivalves is to ……………them into uncontaminated water.
19Seabirds are not vulnerable to mercury as it accumulates in
………………..and it is shed when the birds…………….
20……………………………..in Victorian England
refers to severe
mercury poisoning caused by …………………factory.
21……………….can enhance phytoplankton
photosynthesis ,
and it does not ……………………in the food chain ; and it has no
………………effects on human health.
22After the Minamata disease ,……………….was thought to be
responsible of the outbreak of……………………disease in a Japanese
village . This painful ……………….disease
appeared among
……………….women and resulted in a number of deaths , but
research revealed
that i twas due to …………………………….and
…………………….deficiency.
23……………………..is added to petrol to enhance engine
combustion , since that time there has been an increase use in
lead and thus an increase in ……………………deposition rates.