DCOA Mixed Practice Test #257

Question 1

In a rural setting without access to advanced water purification, what is the most reliable method for making drinking water safe for consumption?

Accepted Answer

D. Boiling the water vigorously for at least one minute — Boiling water vigorously for at least one minute effectively kills most disease-causing bacteria, viruses, and parasites, making it the most reliable method in such settings. Filtering through cloth removes larger particles but not microorganisms, adding bleach requires precise measurement and can be risky, and storing water only prevents recontamination, not purification.

Answer

A. Filtering through a clean cloth

Answer

B. Adding a small amount of household bleach

Answer

C. Storing water in a sealed container

Question 2

Which of the following best explains the genetic basis of sickle cell anemia?

Accepted Answer

B. A missense mutation in the HBB gene causing a substitution of valine for glutamic acid at the 6th position of the beta-globin chain. — Sickle cell anemia is caused by a point mutation (missense mutation) in the HBB gene, where valine replaces glutamic acid at the 6th position of the beta-globin chain. This alters the hemoglobin structure, leading to sickling of red blood cells under low oxygen conditions. Options A, C, and D describe different types of mutations that do not correspond to the actual cause of sickle cell anemia.

Answer

A. A deletion mutation in the HBB gene leading to the absence of beta-globin chains.

Answer

C. A frameshift mutation in the HBB gene resulting in a completely non-functional beta-globin protein.

Answer

D. A nonsense mutation in the HBB gene truncating the beta-globin protein prematurely.

Question 3

Chinakkathoor Pooram:‌​‍

Accepted Answer

Malappuram — Malappuram.‌​‍

Answer

Thrissur

Answer

Wayanad

Answer

Palakkad

Question 4

Which is the hardest material ever known in the universe?‌​‍

Accepted Answer

Diamond — Diamond is the hardest naturally occurring material.‌​‍

Answer

Marble

Answer

Platinum

Answer

Graphite

Question 5

The communicable disease that has been fully controlled by a national programme is:‌​‍

Accepted Answer

Smallpox — Smallpox eradicated worldwide (WHO 1980) — India free via national programme.‌​‍

Answer

Filaria

Answer

Tuberculosis

Answer

Malaria

Question 6

DNA replication is:‌​‍

Accepted Answer

Semi-conservative — Each new DNA has one old + one new strand.‌​‍

Answer

Conservative

Answer

Dispersive

Answer

None

Question 7

UNSCR 1325 (2000) is associated with:

Accepted Answer

Women, Peace and Security Agenda — UN Security Council Resolution 1325 addresses the impact of war on women and their role in peace-building.

Answer

Climate change

Answer

Trade liberalisation

Answer

Nuclear non-proliferation

Question 8

Gravitational potential energy near Earth's surface is:

Accepted Answer

mgh — PE = mgh where h is height above reference.

Answer

½ mv²

Answer

mv

Answer

m/g

Question 9

Chandrayaan-3 Pragyan:‌​‍

Accepted Answer

Rover — Pragyan = rover. Vikram = lander.‌​‍

Answer

Propulsion module

Answer

Lander

Answer

Orbiter

Question 10

CNG (Compressed Natural Gas) is cleaner because:‌​‍

Accepted Answer

Less SPM, SO₂ and CO than petrol/diesel; mostly methane — Delhi buses converted post-Supreme Court 1998 order. ‌​‍Lower particulates; still has CO₂ and NOx.

Answer

Heavier

Answer

Liquid

Answer

No emissions

DCOA Mixed Practice Test #257