Answer:
The correct answers are:
1. closing
2. the ventricles and arteries,
3. a constricted trachea
Lub is the first sound of a heartbeat and is mentioned as S1. It is usually produced due to the closing of tricuspid and and mitral or bicuspid valves present between atria and ventricles.
Tricupsid is located between atrium and ventricle of the right hand side and mitral valve is located between atrium and ventricle of the left hand side. They prevent the back flow of blood from ventricles to their respective atria.
Dub, being the second sound is written as S2. It is produced due to the closing of pulmonary (located between right ventricle and pulmonary artery) and aortic valves (located between left artery and aorta).
These valves prevent the back flow of blood from arteries into the ventricles.
The time between the two sounds is often taken as the measure of the diastole i.e. ventricular filling.
Wheezing refers to a high-pitched sound produced when a person breathes, especially during exhale. It is caused by constriction of the airways or inflammation. It is considered as a symptom of various diseases such as asthma, COPD, allergies, bronchitis etc.
<h2>Development of Plant Needles</h2>
Explanation:
- Seed of pitch pine treated with colchicine delivered tetraploid seedlings which had thick and sporadic needles and less fortunate tallness and diameter growth than ordinary seedlings.
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In test of colchicine-initiated polyploidy in pines, researcher found that a significant number of the polyploid plants returned to a diploid development in light of the fact that the polyploid cells partitioned at a more slow rate and were overwhelmed by the more quickly developing diploid cells which encompassed them.
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The primary needles of both diploid and polyploid plants were more effective at low light intensity than secondary needles, and they had lower compensation points.
Although amino acids may have other formulas, those in protein invariably have the general formula RCH(NH2)COOH, where C is carbon, H is hydrogen, N is nitrogen, O is oxygen, and R is a group, varying in composition and structure, called a side chain.
Nodes. Leaves are attached the plant stem at areas called nodes .
