Which of the following is an example of the skeletal system interacting directly with the
respiratory system?

a the ribcage expands to allow air to enter the lungs.
b the muscles attached to bones contract to lift your leg.
c the marrow inside bones produces white blood cells.
d the vertebrae protect the spinal cord from injury,

a tetrad is the foursome during meiosis made by two homologous chromosomes that have each already replicated into a pair of sister chromatids.

an organism's phenotype is the  form of a trait  that it  displays. for  flowercolor, a pea  plant  can  display  a phenotype of purple or white flowers. an organism's  genotype  is the alleles of a gene it contains. based on his data, mendel concluded that a phenotype can be  determined  by more than one  genotype.

the actual answer was 160934