Answer:
B. False
Explanation:
No; only a small percentage of variants cause genetic disorders—most have no impact on health or development. For example, some variants alter a gene's DNA sequence but do not change the function of the protein made from the gene.
These structures are called Vestigial structures, they resemble structures from the organism's ancestors, but don't have a real purpose for them now.
Pray this helps you :)
Answer: A. The genes encode resistance to antibiotics.
D. The genes are carried on plasmids
F. The "clock"genes are highly mobile between species.
Explanation:
Molecular clock is a tool that is used to calculate the time of the evolutionary events. These are the gene sequences that are used to determine the evolutionary distance between the new and primitive organisms developed on earth. It also measures the random changes just like mutation. Thus the molecular clock is also called as the gene clock or evolutionary clock.
The accuracy of the molecular clock can be increased by the genes that encode for a resistance against the antibiotics, the genes that are carried on the plasmids and the clock genes which are highly mobile among the species.
The Mitral valve which is also known as left atrioventricular prevents blood movement from left ventricle to left atrium.
Explanation:
- Human heart is four chambered.
- Two of these are receiving chambers known as atria and the other two are distributing chamber known as Ventricles.
- Atria are superior chambers and ventricles are inferior chambers.
- The heart has four valves broadly grouped as Atrioventricular valves and Semi lunar valves.
- Atrioventricular valves allows flow of blood from atria to ventricle. These are tricuspid valve and bicuspid valve.
- Semi-lunar valves allow blood to pass out of the heart. These include the pulmonary and aortic valves.
- The pulmonary valve allows blood to flow from right ventricle to the heart while aortic valve allows blood to flow from left ventricle to the Aorta.
- The Tricuspid valve located between the right atrium and right ventricle allows blood to flow from right atrium to the right ventricle.
- The Bicuspid valve ( Mitral valve) located between the left atrium and left ventricle allows the blood flow from left atria to left ventricle.
- Valves maintain the unidirectional flow of blood and thus prevent its back flow.
