In the chart, the organism rr represents a genetically individual. a) heterozygous b) homogeneous c) homozygous d) retrozygous

R is a dominant allele and r is a recessive allele. For the organism to be a homozygous individual, it would have to be either RR or rr. Since the organism is Rr (both alleles), it is heterozygous.

You can remember the difference between homozygous and heterozygous by the words' prefixes:
- the prefix homo- means "same"
- the prefix hetero- means "different"

The answer is ozone layer.

The direction a chemical reaction occurs is represented by an arrow