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General ScienceEasyAsked in: CDS · CDS-II 2023, GK

Which one of the following is the correct combination of organelles and their functions ?

  1. A.Mitochondria - Respiration; Chloroplast - Photosynthesis; Ribosome - Protein Synthesis; Rough endoplasmic reticulum - Transport of proteins
  2. B.Mitochondria - Respiration; Chloroplast - Photosynthesis; Ribosome - Transport of proteins; Rough endoplasmic reticulum - Protein synthesis
  3. C.Mitochondria - Respiration; Chloroplast - Protein synthesis; Ribosome - Photosynthesis; Rough endoplasmic reticulum - Transport of proteins
  4. D.Mitochondria - Photosynthesis; Chloroplast - Respiration; Ribosome - Protein synthesis; Rough endoplasmic reticulum - Transport of proteins

Correct answer

A. Mitochondria - Respiration; Chloroplast - Photosynthesis; Ribosome - Protein Synthesis; Rough endoplasmic reticulum - Transport of proteins

Explanation

The correct answer is A. Mitochondria carry out respiration, chloroplasts photosynthesis, ribosomes make proteins and the rough endoplasmic reticulum transports them.

Mitochondria are called the powerhouse of the cell because aerobic respiration in them releases energy as ATP. Chloroplasts, found in green plant cells, hold chlorophyll and use sunlight to make food by photosynthesis. Ribosomes are tiny particles of RNA and protein that join amino acids into proteins. The rough endoplasmic reticulum gets its name from the ribosomes stuck on its surface; it receives the proteins they make, folds them and carries them through the cell, often on to the Golgi apparatus for packaging.

B is wrong because it swaps the roles of the ribosome and the rough ER. C is wrong because chloroplasts do not make proteins and ribosomes do not carry out photosynthesis. D is wrong because it swaps mitochondria and chloroplasts.

Exam tip: ribosomes make proteins, the rough ER moves them, and the Golgi packs and dispatches them.

Practice Questions

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Q1.General ScienceAsked in: UPSC CAPF · CAPF 2025, Paper IHard

Consider the following statements : 1. The circulation of nitrogen from the inorganic compounds in the soil to form protein in plants and animals and back again is known as the nitrogen cycle. 2. The preparation of ammonia by Haber process is an endothermic reaction. 3. Urea is synthetically made by the action of ammonia and carbon dioxide under high temperature and high pressure. Which of the statements given above is/are not correct?

  1. A.1 and 3
  2. B.2 and 3
  3. C.2 only
  4. D.1 only
Show answer
Correct answer: C. 2 only

The Haber process is exothermic, not endothermic: nitrogen and hydrogen combine to form ammonia and release heat. In the Haber process, N2 + 3H2 ⇌ 2NH3 gives out about 92 kJ for every two moles of ammonia formed.

Q2.General ScienceAsked in: UPSC CAPF · CAPF 2026, Paper IEasy

Which one of the following statements about xylem vessels in plants is not correct?

  1. A.Xylem vessels have lignified cell walls.
  2. B.Phloem sieve tubes are identical to xylem vessels in structure.
  3. C.Dead xylem vessels provide structural support to plants.
  4. D.Water is transported through xylem vessels.
Show answer
Correct answer: B. Phloem sieve tubes are identical to xylem vessels in structure.

Phloem sieve tubes are not like xylem vessels: sieve tubes are living cells with thin walls and sieve plates, while mature xylem vessels are dead, hollow tubes with thick lignified walls.

Q3.General ScienceAsked in: UPSC CAPF · CAPF 2026, Paper IMedium

Which one of the following effects best explains the high partial pressure of carbon dioxide causing haemoglobin to release oxygen in actively respiring tissues?

  1. A.Haldane effect
  2. B.Allee effect
  3. C.Bohr effect
  4. D.Eagle effect
Show answer
Correct answer: C. Bohr effect

The Bohr effect is the fall in haemoglobin's affinity for oxygen when carbon dioxide and acidity rise, so oxygen is unloaded where tissues need it most.

Q4.General ScienceAsked in: UPSC CAPF · CAPF 2026, Paper IEasy

Which one of the following statements about arteries is not correct?

  1. A.The inner lining is made of squamous endothelium.
  2. B.The middle layer is made of smooth muscle and elastic fibres.
  3. C.The outer layer is made of fibrous connective tissue with collagen fibres.
  4. D.Arteries have the thinnest walls amongst any other blood vessels.
Show answer
Correct answer: D. Arteries have the thinnest walls amongst any other blood vessels.

Arteries have the thickest walls of all blood vessels, not the thinnest, because they carry blood away from the heart under high pressure.

Q5.General ScienceAsked in: UPSC CAPF · CAPF 2025, Paper IMedium

Which one of the following is not an exothermic reaction?

  1. A.Dissolution of calcium oxide in water
  2. B.Decomposition of vegetable matter into compost
  3. C.Decomposition of lead nitrate
  4. D.Dilution of sodium hydroxide with water
Show answer
Correct answer: C. Decomposition of lead nitrate

Lead nitrate breaks down only when it is heated strongly, so the reaction absorbs heat and is endothermic. On heating, lead nitrate gives lead oxide, brown fumes of nitrogen dioxide and oxygen: 2Pb(NO3)2 → 2PbO + 4NO2 + O2.