| Term 
 
        | What is the inner lining of the heart called? |  | Definition 
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        | Term 
 
        | What is the heart muscle called? |  | Definition 
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        | Term 
 
        | What is the serous layer covering the heart muscle called? |  | Definition 
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        | Term 
 
        | What is the term for actual genetic makeup? |  | Definition 
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        | Term 
 
        | What is a chromosome pair that may be very different in size? |  | Definition 
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        | Term 
 
        | What are genes that are not expressed unless they are present in homozygous conditions? |  | Definition 
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        | Term 
 
        | What is it called when an individual has identical alleles for a particular trait? |  | Definition 
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