All Categories MCQs
Topic Notes: All Categories
General Description
Plato
- Biography: Ancient Greek philosopher (427–347 BCE), student of Socrates and teacher of Aristotle, founder of the Academy in Athens.
- Important Ideas:
- Theory of Forms
- Philosopher-King
- Ideal State
671
Which of these is a major difference between the Salk (IPV) and Sabin (OPV) polio vaccines?
Answer:
Salk is an inactivated (dead) virus injection, while Sabin is a weakened live virus taken orally
Jonas Salk developed the inactivated polio vaccine (IPV) which is given as an injection. Albert Sabin later developed the oral polio vaccine (OPV), which used a weakened live virus. Both were instrumental in nearly eradicating polio worldwide.
672
What happens to the electron affinity as we move from left to right across a period?
Answer:
It generally becomes more negative (increases)
Electron affinity is the energy released when an electron is added. Across a period, nuclear charge increases and atomic size decreases, making the nucleus better at attracting an incoming electron, thus releasing more energy.
673
Which of the following is an example of 'Passive Immunity'?
Answer:
A baby receiving antibodies from mother's milk
Passive immunity involves the transfer of pre-made antibodies from one individual to another. Because the recipient's own immune system didn't produce them, no memory cells are created, and the protection is temporary. Breast milk provides natural passive immunity to infants.
674
Tuberculosis (TB) is a serious infectious disease that mainly affects the lungs. Which microorganism is responsible for TB?
Answer:
Mycobacterium tuberculosis (Bacterium)
Tuberculosis is caused by a specific type of bacterium called Mycobacterium tuberculosis. It is an airborne pathogen that can stay suspended in the air for hours, making it highly transmissible in crowded or poorly ventilated environments.
675
Which of these is a covalent network solid?
Answer:
Diamond
In diamond, each carbon atom is covalently bonded to four other carbon atoms in a continuous 3D giant lattice. This makes it extremely hard with a very high melting point.
676
Which of the following is a physical property of liquids?
Answer:
Ability to flow (viscosity)
Liquids have the ability to flow because their particles can slide over each other while remaining in contact. This property is quantified as viscosity (resistance to flow).
677
Electronegativity _______ down a group.
Answer:
Decreases
Down a group, atomic size increases and the shielding effect increases. This makes the nucleus less effective at attracting shared electrons in a bond, thus decreasing electronegativity.
678
What is the shape of a water molecule ($H_2O$)?
Answer:
Bent (V-shaped)
Although the oxygen atom has four electron pairs (two bonding, two lone) arranged tetrahedrally, the molecular shape—the position of the atoms—is bent or V-shaped with an angle of about 104.5 degrees.
679
Which specific cells of the immune system are responsible for 'remembering' a pathogen and providing a rapid response upon re-exposure?
Answer:
Memory B and T cells
After an initial infection or vaccination, a subset of lymphocytes becomes memory cells. These cells circulate in the blood for years and can quickly recognize the pathogen if it enters the body again, leading to a much faster and stronger secondary immune response.
680
Which of the following statements about 'Smallpox' is true?
Answer:
It was the first and only human infectious disease to be completely eradicated through vaccination
Thanks to a massive global vaccination campaign led by the World Health Organization (WHO), smallpox was declared officially eradicated in 1980. This remains one of the greatest achievements in the history of public health.