<span>carbon has four valence electrons in its outermost shell .. which makes it able to form four bonds to complete its valence shell ..
it forms large number of chains with its own self which makes it useful .. also it forms bonds with oxygen and hydrogen forming large organic compounds of great importance. </span>
<span>please mark as brainliest.</span>
Abiotic and biotic factors
<u>Answer:</u>
<em>Low calcium level in body may cause a condition called hypocalcemia.
</em>
<u>Explanation:</u>
When a <em>person has the condition of hypocalcemia his/her muscles and nerves that are releted to calcium levels in blood</em> will undergo spasms or twitching. This is generally termed as muscular irritability. <em>Muscle cramps in leg and arms are symptoms of hypocalcemia.
</em>
When the fall in calcium levels is sudden then the <em>twitching of muscles</em> will be more evident. Calcium absorption is only possible if there is adequate supply of vitamin D in our body. <em>Thus the levels of calcium and vitamin D should be well maintained to avoid hypocalcemia.
</em>
Answer: Older fossils have been found and extinct/or animals from older times have had similar characteristics to animals found closer to our time/or the present.
Answer:
Skeletal tissue pls be right
Explanation:
