Answers to some common questions (Part-2)

By: Aamarpali Puri

Q: What all workers and medical staff who are likely to be near radioactive or ionizing sources must wear to monitor their exposure to radiations?

A: To monitor their exposure to radiations they must wear lapel radiation badges containing photographic film.

Q: The aprons of those who are involved in radiotherapy treatment are lined with which element?

A: Lead.

Q: What will be the order of danger from alpha, beta and gamma radiations if the radioactive source gets inside the body?

A: The ‘danger’ order is alpha > beta > gamma.  The bigger the mass or charge of the particle, the bigger will be its ionizing impact on atoms/molecule. Because the order of mass is 4 > 1/1850 > 0, and for electric charge the order is 2+ > -1 > 0.  If the radioisotope is in the body the radiation impacts directly on cells with the consequences described above.

Q: What will be the order of danger from alpha, beta and gamma radiations if the radioactive source is outside the body?

A: If the radioactive source is outside the body, the order danger is reversed to gamma > beta > alpha because the danger order follows the pattern of penetrating power. The smaller the mass and charge the more penetrating the radiation (reverse the order of above). Gamma and beta are the most penetrating and will reach vital organs in the body and be absorbed.  Most gammas passes through soft tissue but some is inevitably absorbed by cells.  Alpha radiation would not penetrate clothing and is highly unlikely to reach living cells.

Q: How radioactive isotopes help in smoke detecting?


Q: How α particles work in smoke detectors?

A: As Alpha particles are easily stopped, an alpha source is used in some smoke detectors. A sealed alpha source of Americium-241 (half-life 458 years, producing constant signal) sends a stream of alpha particles to a sensor across an air gap. Any smoke present will block the alpha particles and change the sensor signal, this change in signal triggers the alarm. Beta and gamma radiation would be of no use because the smoke particles would not stop them. There will be no change in signal and no alarm will be triggered.

Q: How cartilaginous fishes solve the problem of conserving body water in strongly hypertonic environment?

A: They solve this problem by maintaining a high concentration of urea in their blood.

Q: Why is water great solvent?

A: That’s because the charged ends of the water molecules are attracted to the charges on other molecules. Water molecules will surround soluble molecules or ions in a hydration shell. This helps keep the molecules in solution.

Q: What makes insects capable of walking on the surface of water?

A: Surface tension of water.

Q: Which important defensive compound is present in plant?

A: Terpenes.

Q: Which bond maintains protein’s proper shape?

A: Hydrogen bond between water molecules and amino acids.

Q: In human body calories ingested in a meal and not used immediately by tissues are converted to triglycerides and transported to fat cells to be stored? Excess of these triglycerides is harmful for human body, why?

A: They are harmful because they cause body to produce excess cholesterol.

Q: What is the function of formic acid in ants?

A: Alarm and defense.

Q: How the motion of planets in an orbit and that of electrons in orbit different?

A: Planet moves around the sun in an orbit which can be plotted and electrons are in orbital which is the space around nucleus where probability of finding electrons is maximum.

Q: When a metal is melted what happens to its bonds?

A: On melting bond is loosened not broken.

Q: Why moss is used in dressing of wounds?

A: It has ability to absorb blood or any liquid substance.

Q: Occurrence of aquatic moss at some place indicates presence of which element in soil?

A: Calcium

Q: How Bryophytes prevent soil erosion?

A: They prevent soil erosion due to their trample resistant structure and their regenerative ability.

Q: How Bryophytes aid in moisture conservation?

A: They envelop the forest floor and tree trunks and aid in moisture conservation.

Q: Why Merceya, Mielichhoferia elongate are known as copper mosses?

A: They are known as copper bryophytes because they grow in copper rich soil.


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