601: The Function of heavy water in a nuclear reactor is to
(a) Stop the nuclear reaction
(b) Slow down the speed of neutrons
(c) Cool down the reactor
(d) Increase the speed of neutrons
Explanation:
Under the first stage of the Department of Atomic Energy's nuclear power programme, a series of Pressurised Heavy Water Reactors, using natural uranium as fuel and heavy water as both coolant and moderator, has already been built. In nuclear reactor heavy water is used as a moderator. It's there to act as a neutron moderating fluid. Moderator is the material in the core which slows down the neutrons released from fission so that they cause more fission. It is usually water, but may be heavy water or graphite. If graphite or heavy water is used as moderator, it is possible to run a power reactor on natural instead of enriched uranium. Natural uranium has the same elemental composition as when it was mined (0.7 per cent U-235, over 99.2 per cent U-238), enriched uranium has had the proportion of the fissile isotope (U-235) increased by a process called enrichment, commonly to 3.5 - 5.0 per cent. In this case the moderator can be ordinary water, and such reactors are collectively called light water reactors. Because the light water absorbs neutrons as well as slowing them, it is less efficient as a moderator than heavy water or graphite.
602: What is Cas9 protein that is often mentioned in news?
(a) A molecular scissors used in targeted gene editing
(b) A biosensor used in the accurate detection of pathogens in patients
(c) A gene that makes plants pest-resistant
(d) A herbicidal substance synthesized in genetically modified crops
Explanation:
CRISPR Cas9 is an acronym for "Clustered Regularly Interspaced Short Palindromic Repeats." CRISPR genome engineering technology enables scientists to easily and precisely edit the DNA of any genome.
Source: https://www.synthego.com/learn/crispr
603: Which is not a parasite?
(a) Tick
(b) Housefly
(c) Bed bug
(d) Louse
604: Which one of the following statements is not correct?
(a) Hepatitis B virus is transmitted much like HIV.
(b) Hepatitis B. unlike Hepatitis C, does not have a vaccine.
(c) Globally, the number of people infected with Hepatitis B and C viruses arc several times more than those infected with HIV.
(d) Some of those infected with Hepatitis B and C viruses do not show the symptoms for many years.
Explanation:
The hepatitis B vaccine is a safe and effective vaccine that is recommended for all infants at birth and for children up to 18 years. The hepatitis B vaccine is also known as the first "anti-cancer" vaccine because it prevents hepatitis B, the leading cause of liver cancer worldwide.
Source: https://www.hepb.org/prevention-and-diagnosis/vaccination/
605: Sex of a child is determined by the:
(a) Chromosomes of father
(b) Chromosomes of mother
(c) Rh factor of parents
(d) None of these