The dominant trait is hornless.
If this is correct, then the original bull is a heterozygote:
H = hornless
h = horned
Bull is Hh
Cross 1: Hh x hh (horned female) - offspring is hh (horned)
Cross 2: Hh x Hh (hornless female) - offspring is hh (horned)
Cross 3: Hh x hh (horned female) - offspring is Hh (hornless)
Cross 3 is the key to confirming this because the only way to get a hornless offspring would be if hornless is recessive.
Lead emission since early 1980s have DECREASE DUE TO LEAD FREE GASOLINE.
Lead is a natural occurring element that is found in small quantity in rocks and soils. Lead emission is an important environmental health issue because a very small quantity of lead can cause adverse effects on the nervous system of unborn babies and young children. Because of this, the government took all necessary measures to ensure that its emission was drastically reduced.
The answer is C. solid iron and nickel
The substance is called DNA.
A example of a nerve cell is a nerve cell