DCOA Mixed Practice Test #262

Question 1

Which of the following best describes the Hoffmann bromamide reaction?‌​‍

Accepted Answer

Amide → amine with one less carbon (Br₂ + NaOH) — RCONH₂ → RNH₂. Degradation for primary amine synthesis.‌​‍

Answer

Amide to alcohol

Answer

Amide to ketone

Answer

Amide to ester

Question 2

CRISPR-Cas9 technology has revolutionized gene editing. Which of the following statements accurately describes its core principle and application in addressing genetic disorders?

Accepted Answer

B. It utilizes a guide RNA to direct a nuclease enzyme to specific DNA sequences, allowing precise cuts for gene inactivation or correction. — The correct answer is B. CRISPR-Cas9 technology uses a guide RNA (gRNA) to precisely target a specific DNA sequence, where the Cas9 nuclease enzyme then makes a cut. This allows for gene inactivation, correction of mutations, or insertion of new genetic material at a precise location. Option A describes traditional gene therapy methods using viral vectors to deliver entire genes. Option C refers to post-transcriptional or post-translational modifications, not direct gene editing. Option D describes random mutagenesis, which is not the controlled and precise mechanism of CRISPR.

Answer

A. It involves inserting entire functional genes into target cells using viral vectors, replacing defective ones.

Answer

C. It primarily focuses on altering the protein products of genes post-transcription, without directly modifying the DNA sequence.

Answer

D. It induces random mutations across the genome to increase genetic diversity, hoping for a beneficial outcome.

Question 3

Nylon 6,6 is made from which of the following?‌​‍

Accepted Answer

Hexamethylenediamine + adipic acid — Condensation polymer (polyamide). Named after 6+6 carbons. Strong, elastic — used in ropes, clothing.

Answer

Ethylene

Answer

Isoprene

Answer

Styrene

Question 4

Number of rivers in Kerala:‌​‍

Accepted Answer

44 — 44 rivers (41 west-flowing + 3 east-flowing).‌​‍

Answer

41

Answer

34

Answer

50

Question 5

A light year is a unit of:‌​‍

Accepted Answer

Distance — A light year is a unit of distance — the distance light travels in one year (~9.46 trillion km). ‌​‍Despite the name, it measures distance, not time.

Answer

Time

Answer

Speed

Answer

Mass

Question 6

Osteoporosis is related to:‌​‍

Accepted Answer

Bones — Osteoporosis = weakening of bones due to loss of calcium. ‌​‍Common in elderly women.

Answer

Muscles

Answer

Nerves

Answer

Blood

Question 7

The PLI (Production Linked Incentive) scheme covers how many sectors?‌​‍

Accepted Answer

14 — PLI scheme was announced for 14 key sectors including electronics, pharma, auto, textiles, and semiconductors.‌​‍

Answer

13

Answer

10

Answer

18

Question 8

DNA structure was discovered by:‌​‍

Accepted Answer

Watson and Crick — James Watson and Francis Crick discovered the double helix structure of DNA in 1953.‌​‍

Answer

Mendel

Answer

Darwin

Answer

Pasteur

Question 9

Follicle stimulating hormone (FSH) in males:‌​‍

Accepted Answer

Stimulates Sertoli cells (spermatogenesis) — LH stimulates Leydig → testosterone. ‌​‍In females: FSH stimulates follicle growth; LH triggers ovulation.

Answer

Produces testosterone

Answer

No function

Answer

Stimulates Leydig cells

Question 10

Perfect numbers are:

Accepted Answer

Rare — Few known perfect numbers.

Answer

Common

Answer

Infinite known

Answer

Only 6

DCOA Mixed Practice Test #262