Science & Technology

CDS 202512 questions

1. Q26

   Tooth enamel of humans is made up of :

   • ACalcium phosphate
   • BSodium hydrogen carbonate
   • CSodium hydroxide
   • DLactic acid
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   Correct answer: (A) Calcium phosphate

   Tooth enamel, the hardest tissue in the body, is composed mainly of calcium phosphate in the form of hydroxyapatite crystals. Lactic acid produced by mouth bacteria actually erodes this enamel, and the sodium compounds listed are not structural constituents of teeth.

2. Q27

   The inner lining of the human small intestine has numerous finger-like projections called :

   • ASphincter
   • BVilli
   • CEnzymes
   • DPlaques
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   Correct answer: (B) Villi

   The finger-like projections lining the small intestine are called villi; they greatly increase the surface area for absorption of digested nutrients. A sphincter is a ring of muscle, enzymes are catalytic proteins, and plaques are unrelated deposits, so none of these describe the projections.

3. Q28

   Which of the following represent disaccharides?

   • AStarch and glycogen
   • BGlucose and galactose
   • CMaltose and lactose
   • DRibose and xylose
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   Correct answer: (C) Maltose and lactose

   Maltose (glucose+glucose) and lactose (glucose+galactose) are disaccharides made of two monosaccharide units. Starch and glycogen are polysaccharides; glucose and galactose are monosaccharides; and ribose and xylose are also single-sugar pentoses.

4. Q29

   Which one of the following organelles can be seen in a prokaryotic cell?

   • AMitochondria
   • BDefinitive nucleus
   • CRibosomes
   • DGolgi bodies
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   Correct answer: (C) Ribosomes

   Ribosomes are the only organelle in the list present in prokaryotic cells, where they carry out protein synthesis. Prokaryotes lack a membrane-bound (definitive) nucleus, mitochondria and Golgi bodies, all of which are features exclusive to eukaryotic cells.

5. Q30

   A solution with a pH value less than 7 is a/an :

   • ANeutral solution
   • BBasic solution
   • CAcidic solution
   • DHypotonic solution
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   Correct answer: (C) Acidic solution

   A pH value below 7 indicates an excess of hydrogen ions, defining an acidic solution. A pH of exactly 7 is neutral and above 7 is basic; 'hypotonic' refers to solute concentration and is unrelated to pH.

6. Q31

   Which language uses the symbolic representation of machine codes needed to program a particular processor or processor family ?

   • AMachine Language
   • BAssembly Language
   • CHigh-Level Language
   • DAll of the above
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   Correct answer: (B) Assembly Language

   Assembly language uses mnemonic symbolic representations (like MOV, ADD) of the binary machine codes specific to a particular processor or processor family, making programming more human-readable than raw machine language. Machine language is pure binary, while high-level languages are hardware-independent, so neither fits the description of 'symbolic representation of machine codes'.

7. Q32

   What are the uses of software ports ? 1. Connect client computer to server 2. Connect external devices to computer 3. Identify different services like email, file transfer 4. Connecting peripherals like cameras, scanners Select the answer using the code given below :

   • A1 and 2
   • B1 and 3
   • C2 and 3
   • D2 and 4
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   Correct answer: (B) 1 and 3

   Software (logical) ports are numeric identifiers that connect a client to a server and distinguish network services such as email (SMTP port 25), file transfer (FTP port 21), etc., so statements 1 and 3 are correct. Connecting external physical devices, peripherals like cameras and scanners refers to hardware ports (USB), not software ports, ruling out 2 and 4.

8. Q33

   Assuming the computer is a 4-bit computer, what result is produced after subtraction of 3 from 5 using the 2's complement representation ?

   • A0101
   • B10010
   • C1101
   • D11001
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   Correct answer: (B) 10010

   In 2's complement, 5 = 0101 and 3 = 0011; the 2's complement of 3 is 1101, so 5 - 3 = 0101 + 1101 = 10010, where the leading 1 is the discarded carry-out and the true 4-bit result 0010 equals decimal 2. The option showing the full 5-bit sum 10010 is the intended answer.

9. Q34

   Which one of the following is not a logical operator ?

   • ANOT
   • BOR
   • CAND
   • DDivision
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   Correct answer: (D) Division

   NOT, OR and AND are the fundamental logical (Boolean) operators used in logic and programming. Division is an arithmetic operator, not a logical one, so it is the odd one out.

10. Q35

    Which among the following are the purposes of deploying a Firewall? 1. Examine each packet arriving from Internet 2. Prevent unauthorised access 3. Block suspicious activity 4. Interconnect telephones Select the answer using the code given below:

    • A1 and 2 only
    • B1, 3 and 4
    • C2 and 3 only
    • D1, 2 and 3
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    Correct answer: (D) 1, 2 and 3

    A firewall examines each packet arriving from the Internet, prevents unauthorised access and blocks suspicious activity, so statements 1, 2 and 3 are its purposes. Interconnecting telephones is unrelated to firewalls, so statement 4 is excluded.

11. Q36

    Which of the following statements about India's military arsenal is/are correct? 1. HAMMER is a weapon system built for the Rafale fighter aircraft. 2. SCALP cruise missile is also known as Storm Shadow. 3. BrahMos missiles are built under a joint venture between India and Russia. Select the answer using the code given below :

    • A1 and 2 only
    • B2 and 3 only
    • C1, 2 and 3
    • D3 only
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    Correct answer: (C) 1, 2 and 3

    HAMMER is a precision air-to-ground weapon integrated on India's Rafale jets, the SCALP cruise missile is the French designation of the same weapon marketed as Storm Shadow, and BrahMos is an India-Russia (DRDO-NPOM) joint venture. All three statements are correct (C).

12. Q37

    Recently, ICAR (Indian Council of Agricultural Research) has developed the world's first genome-edited rice varieties. Which of the following statements is/are correct with respect to the developed products? 1. The genome-edited varieties – DRR Rice 100 (Kamla) and Pusa DST Rice 1 have been developed by ICAR-IARI, New Delhi. 2. DRR Rice 100 (Kamla), based on Samba Mahsuri, has a shorter duration of maturity. Select the answer using the code given below:

    • A1 only
    • B2 only
    • CBoth 1 and 2
    • DNeither 1 nor 2
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    Correct answer: (B) 2 only

    Statement 1 is wrong because DRR Rice 100 (Kamla) was developed by ICAR-IIRR (Hyderabad), while only Pusa DST Rice 1 came from ICAR-IARI, New Delhi. Statement 2 is correct: DRR Rice 100 (Kamla), derived from Samba Mahsuri, matures earlier (shorter duration), so B is right.