Answer:
3
Explanation:
Heterozygous mice at both loci would be BbAa genotype.
B (black) is dominant over b (white) but the presence of A results in agouti.
Crossing two heterozygous:
BbAa x BbAa
Progeny
<em>9 B_A_ - Agouti</em>
<em>3 bbA_ - agouti</em>
<em>3 B_aa - Black</em>
<em>1 bbaa - white</em>
Hence, 3 out of 16 progeny will be black in color.
<em>See the attached image for the Punnet's square analysis of the cross.</em>
Answer:
Option A, most closely related to mammals
Explanation:
Insects like arthropods and molluscs have an open circulatory system and thus do have a distinguishable heart. Fish has two chambered heart. Reptiles have three chambered heart. Amphibians too have a three chambered heart.
All mammals and fish have four chambered heart. The right and left sides of the chambers have restricted entry and hence remain intact from each other
Hence, option A is correct
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Answer:
Mammals first appeared
Explanation:
The dinosaurs became extinct one million years after the Cenozoic era started. The mammals first appeared as the modern culture first appeared in that era.
