DCOA Mixed Practice Test #287

Question 1

pH value of pure water is:‌​‍

Accepted Answer

7 — Pure water has a pH of 7, which is neutral. ‌​‍pH below 7 is acidic, above 7 is alkaline/basic. This is one of the most basic chemistry facts tested in PSC.

Answer

14

Answer

0

Answer

1

Question 2

Oxygenated blood from lungs enters:‌​‍

Accepted Answer

Left atrium — Pulmonary veins → left atrium.‌​‍

Answer

Right ventricle

Answer

Right atrium

Answer

Left ventricle

Question 3

Moment Magnitude Scale:‌​‍

Accepted Answer

Replaces Richter for large quakes — Mw preferred for M > 7.‌​‍

Answer

Different measure

Answer

Same as Richter

Answer

Unused

Question 4

Chain reaction in U-235 occurs because each fission produces:

Accepted Answer

~2-3 neutrons (some cause further fissions) — Critical mass needed to sustain chain. Moderator slows neutrons to increase fission probability.

Answer

0 neutrons

Answer

1 neutron

Answer

10 neutrons

Question 5

Which of the following infections is primarily transmitted through the fecal-oral route?

Accepted Answer

B. Typhoid fever — Typhoid fever is transmitted via the fecal-oral route, typically through contaminated food or water. Hepatitis B is primarily transmitted through blood and body fluids. Tuberculosis is airborne, and malaria is transmitted by mosquitoes.

Answer

A. Hepatitis B

Answer

C. Tuberculosis

Answer

D. Malaria

Question 6

Kerala's most densely populated district:‌​‍

Accepted Answer

Alappuzha (~1,500/km²) — Kerala density ~860/km². Idukki least dense. Kerala has >90% literacy.‌​‍

Answer

Thiruvananthapuram

Answer

Wayanad

Answer

Idukki

Question 7

The SI unit of electric charge is:

Accepted Answer

Coulomb — Coulomb (C); 1 C = 1 A·s.

Answer

Ampere

Answer

Volt

Answer

Ohm

Question 8

Makaravilakku:

Accepted Answer

Sabarimala festival — Major Sabarimala festival (January).

Answer

Onam

Answer

Vishu

Answer

Navratri

Question 9

Protected forests:

Accepted Answer

Some use allowed — Regulated use.

Answer

Fully open

Answer

Strict

Answer

None

Question 10

Penicillins are a class of beta-lactam antibiotics. Their antibacterial activity is primarily due to the presence of the beta-lactam ring, which acts by:

Accepted Answer

D. Inhibiting bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs). — Penicillins, like other beta-lactam antibiotics, exert their bactericidal effect by inhibiting the synthesis of the bacterial cell wall. They achieve this by covalently binding to and inactivating penicillin-binding proteins (PBPs), which are transpeptidases essential for peptidoglycan cross-linking. The other options describe mechanisms of action of different classes of antibiotics.

Answer

A. Inhibiting bacterial protein synthesis by binding to the 50S ribosomal subunit.

Answer

B. Disrupting bacterial cell membrane integrity.

Answer

C. Interfering with bacterial DNA replication.

DCOA Mixed Practice Test #287