3.8 billion – 2.5 billion years ago
The Archean is the name of the age which started with the shaping Earth. This time of Earth's history endured quite a while, over 2.5 billion years. When the archean age ended the earth was just coming alive.
Answer: a). AA
Explanation: Every trait is controlled by at least a pair of gene. Genes have different forms known as alleles. Alleles can be dominant or recessive. A dominant allele expresses itself in the presence of a recessive allele and masks the effect of a recessive allele. A recessive allele cannot express itself in the presence of a dominant allele and it's effect is masked by a dominant allele. Dominant alleles are usually written in upper cases such as A, T, while recessive alleles are usually written in lower cases such as a, t. The two alleles that determines a trait is called a genotype. A genotype can be homozygous if the two alleles are identical such as in AA or aa
and can be heterozygous if the two alleles are not identical such as in Aa, Tt.
BB or Bb because brown eyes are dominant and blue eyes are recessive.
Answer:
B. Populations of amphibians in a few local areas have declined dramatically in the last few decades
Explanation:
The continuous, low-level extinction of species that has occurred throughout the World and at least six species of frogs have not been seen for one to three decades and also it has recently been discovered that some species of salamander-specific chytrid has gone into extinction
I believe it is D bcuz there is no more reproducing of that species so it will eventually die out.
