The mass of a tree is primarily carbon. The carbon comes from carbon dioxide used during photosynthesis. During photosynthesis, plants convert the sun's energy into chemical energy which is captured within the bonds of carbon molecules built from atmospheric carbon dioxide and water.
"Coronary heart disease, North America’s number one cause of death, has been linked with the competitive, hard-driving, impatient, and (especially) anger-prone Type A personality. Under stress, the body of a reactive, hostile person secretes more of the hormones that accelerate the buildup of plaque on the heart’s artery walls. Type B personalities are more relaxed and easygoing. Chronic stress also contributes to persistent inflammation, which heightens the risk of clogged arteries and depression."
OR
Coronary heart disease (CHD) could be the thinning or impediment in the coronary thrombosis veins, normally brought on by coronary artery disease. Coronary artery disease (at times termed “stiffing” or maybe “blocking” in the arterial blood vessels) may be the build-up associated with trans fat and fatty deposits (named plaques) around the intrinsic artery walls.
Answer:
D. There is no enough oxygen in the culture fluid
Explanation:
The cells in the test tube need to carryout one of the important metabolic processes of living organisms - respiration. The process involves the breakdown of glucose to generate energy for other metabolic processes in the cell.
Respiration can be carried out in the presence of oxygen (aerobic) or in the absence of oxygen (anaerobic). Human cells are primarily aerobic but can carryout respiration anaerobically in the presence of inadequate oxygen.
For aerobic respiration, glucose is broken down in the presence of oxygen to produce carbon-dioxide, water and energy in the form of ATP:

<em>In the absence of oxygen, the glucose becomes converted to lactic acid and a smaller amount of ATP is produced as compared to aerobic respiration.</em>
<em>Hence, lactic acid gradually builds up in the absence of oxygen due to anaerobic respiration.</em>
The correct option is D.
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