DCOA Mixed Practice Test #819

Question 1

PCR (Polymerase Chain Reaction) is used for:

Accepted Answer

DNA amplification in vitro — Kary Mullis (Nobel 1993). Uses Taq polymerase (heat-stable). Denaturation 94°C, annealing 55°C, extension 72°C.

Answer

Protein synthesis

Answer

DNA degradation

Answer

Only sequencing

Question 2

Biosphere:

Accepted Answer

Sum of all ecosystems — All life zones on Earth.

Answer

Only plants

Answer

Atmosphere

Answer

Hydrosphere

Question 3

Anemometer measures:‌​‍

Accepted Answer

Wind speed — Wind speed.‌​‍

Answer

Humidity

Answer

Rainfall

Answer

Temperature

Question 4

The ozone layer is depleted mainly by:‌​‍

Accepted Answer

CFCs (Chlorofluorocarbons) — CFCs (used in old refrigerators/ACs) release chlorine atoms that destroy ozone (O₃) molecules in the stratosphere.‌​‍

Answer

Carbon Dioxide

Answer

Methane

Answer

Nitrogen

Question 5

The CGS unit of force is:‌​‍

Accepted Answer

Dyne — Dyne is the CGS unit of force. Newton is the SI unit. 1 N = 100,000 dynes.‌​‍

Answer

Newton

Answer

Joule

Answer

Watt

Question 6

Fire extinguisher gas:‌​‍

Accepted Answer

CO₂ — CO₂ — non-combustible, smothers fire.‌​‍

Answer

O₂

Answer

N₂

Answer

H₂

Question 7

The RTE Act, 2009 emphasizes the 'no detention policy' up to which class to ensure continuous learning for all children?

Accepted Answer

B. Class 8 — The RTE Act, 2009 mandates the 'no detention policy' up to Class 8 to prevent children from being held back due to academic failures, promoting inclusive education. After Class 8, schools can detain students based on performance.

Answer

A. Class 5

Answer

C. Class 10

Answer

D. Class 12

Question 8

Nitrogen cycle bacteria:‌​‍

Accepted Answer

Rhizobium, Nitrosomonas — Various nitrogen-fixing/nitrifying bacteria.‌​‍

Answer

Staphylococcus

Answer

E. coli

Answer

Only Rhizobium

Question 9

A 14-year-old girl is extremely self-conscious about a minor pimple on her face, believing that everyone she encounters will notice it and judge her negatively. This heightened self-awareness and belief that others are constantly observing and evaluating her is an example of:

Accepted Answer

B. Imaginary audience — The 'imaginary audience' is a cognitive distortion common in adolescent egocentrism, where adolescents believe that others are as interested in them as they are in themselves, leading to intense self-consciousness. 'Personal fable' is the belief in one's uniqueness and invincibility, while deductive reasoning and concrete operational thought are different cognitive processes.

Answer

A. Deductive reasoning

Answer

C. Personal fable

Answer

D. Concrete operational thought

Question 10

Jahangir's queen who effectively ran the empire in his later years was:

Accepted Answer

Nur Jahan (Mehrunnisa) — Married Jahangir 1611. Coins issued in her name; part of junta with father Itimad-ud-Daula and brother Asaf Khan. Commissioned Itimad-ud-Daula's tomb (Agra, 'Baby Taj').

Answer

Mumtaz Mahal

Answer

Jodha Bai

Answer

Jahanara

DCOA Mixed Practice Test #819