To perform this test to check if gold is real, make a light, tiny scratch on the item using a small nail file. Choose a spot that is not noticeable if possible. Use a dropper to apply a small drop of nitric acid to the scratch. If there is no reaction, then the piece is probably made from real gold.
Answer:
sinoatrial node and atrioventricular node
Hippodamia convergens and Hippodamia variegata can mate but cannot produce fertile offspring because the number of chromosomes can make the development of the embryo unfeasible.
<h3>What are fertile hybrids?</h3>
The crossing between plants or animals of similar species can generate beings that, despite being hybrids, are fertile, even though in the initial phase of cell multiplication some chromosomes do not find the respective pair.
<h3>Why don't hybrids reproduce?</h3>
These differences in the number of chromosomes can make the development of the embryo unfeasible, as the alignment of equivalent chromosomes from the female and the male is necessary for the division of the fertilized cell to occur. When this alignment does not occur, the cell does not reproduce and dies.
With this information, we can conclude that Hybrid animals are beings from genetic crosses between different species, but of the same genus, that is, when two different animals cross and a new animal appears, usually sterile, due to their incompatible genes: the hybrid animal.
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