Answer: Fossils of limb structures provide evidence that ancient and modern tetrapods are related because it backs up the fact that both ancient and modern tetrapods follow the one bone two bone many bone digit pattern. It suggests to how modern and ancient tetrapods have the ancestry which come from early tetrapods.
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Answer:
<h3>The genes that caused scales to become feathers in the early ancestors of birds </h3>
Answer:
Channels discriminate between solutes mainly on the basis of size and electric charge.
Explanation:
The correct answer is A. Nebula, star of seven stellar masses, a red supergiant, supernova, black hole.
Explanation
Stars have a life cycle that begins with the gravitational collapse of a gaseous nebula. Subsequently, thermonuclear fusion occurs that allows the conversion of hydrogen into helium, this causes the released energy to pass through the star and radiate in a phase called the star of seven stellar masses. After several billion years, the star passes to the "red giant" stage. Here the star contracts and raises its temperature. After this, the stars (which have masses greater than the sun) detach from their layers forming supernovae, and later, these give rise to "black holes". According to the above, the correct answer is A. Nebula, star of seven stellar masses, a red supergiant, supernova, black hole.
Physical exercise preserves bone mass. Measurements of bone biomarkers may reflect the events in bone during exercise. Fifteen healthy, well-trained individuals (7 men and 8 women) performed a running test for 21 min until exhaustion. Venous blood samples were drawn before and 30 min after the exercise to measure the levels of osteocalcin, the carboxyterminal propeptide of type I procollagen (PICP) and the carboxyterminal cross-linked telopeptide of type I collagen (ICTP). After exercise, the women had a marked increase in serum osteocalcin concentrations (from 7.5±5.0 μg/1 to 11.5±3.0 μg/1), whereas the level was unaffected in the men (from 14.5±3.0 μg/1 to 13.5±4.6 μg/l). In the men there was a marked increase in PICP (from 240±47 μg/1 to 268±56 μg/1) that was not seen in the women (from 244±70 μg/1 to 253±60 μg/1). In neither group did ICTP levels change. In conclusion, significant responses were seen in PICP and osteocalcin during exercise, indicating that such measurements may be valuable for the further delineation of the effects of physical activity on bone. Furthermore, the different responses in men and women point to interesting areas for future studies.
