I think that the best answer is C, it is not influenced by economic conditions.
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Answer:
Heart valves or the closure of the mitral and tricuspid atrioventricular (AV) valves at the beginning of ventricular systole and the closure of the aortic valve and pulmonary valve at the end of ventricular systole.
Explanation:
The heart tone “lub,” or S1, is caused by the closure of the mitral and tricuspid atrioventricular (AV) valves at the beginning of ventricular systole.
The heart tone “dub,” or S2 ( a combination of A2 and P2), is caused by the closure of the aortic valve and pulmonary valve at the end of ventricular systole.
Food chains are for example something that another thing eats and it goes down to many different selections and starts off big and vies to small things
Deficiency of calcium in plants causes reduced internode length and crinkled leaves.
Initial signs of calcium Deficiency include localized tissue necrosis that stunts plant growth and causes young leaves to curl or have necrotic leaf margins, and terminal buds and root tips to eventually die. New growth and tissues that are expanding quickly on the plant are typically the first to be harmed.
- These include boron, copper, iron, manganese, molybdenum and zinc. Most nutrient deficiencies are caused by a lack of nutrient content in the growing medium or nutrient solution
- Plants require calcium in order to develop new growth points and root tips. Symptoms of a deficiency include decreased growth in new leaf, buds, and roots. Younger leaves curl downward and develop tip burn, which is the browning of the leaf edges and tips.
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