Answer:longitudinal design
Explanation: we need to know what is longitudinal design. By definition,
longitudinal design is the study of variables or group of variables which have similar cases and repeated over a long on short period of time. This cases happened between a similar group( teenage girls ), and it happened repeatedly over a long period of time, so this will require a longitudinal design.
Answer:
Bicuspid aortic valve is a type of abnormality in the aortic valve in the heart. In bicuspid aortic valve, the valve has only two small parts, called leaflets, instead of the normal three. This condition is present from birth. It can occur with other heart defects. The heart's ventricles are the two lower chambers of the heart.
location :
Bicuspid valve is one of the four valves of the heart which is situated between the left atrium and the left ventricle. Tricuspid valve is one of the four valves of the heart which is situated between the right atrium and the right ventricle. Bicuspid valve is present in between the left atrium and the left ventricle.
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The answer is 'Cambrian' explosion. This took place approximately 541 million years ago. 'Explosion' refers to the evolution of a large range of new major animal phyla. Scientists know this by the large number of diverse fossils from this period. Prior to this period, organisms were single-celled, but over the Cambrian Explosion, lasting about 80 million years, life forms diversified rapidly to resemble the life forms existing today.
The answer for this question would be Integument, digestive, respiratory and urogenital.
The largest system that contact with the external environment would be integument and digestive. That makes two system has normal flora of microbes and not sterile like the other systems. Normal flora of microbes will prevent the pathogen microbe grows so it gives some benefit.
In biology, the biotic factors pertain to the living components of Earth while the abiotic factors are those non-living chemicals and physical factors. The only choice that is not an interaction between biotic and abiotic factors is the third choice, "C. male elk fighting over a female".
