Which of the following cells form components of complex permanent tissue in plants ? I. Companion cells II. Sieve tubes III. Tracheids IV. Vessels Select the answer using the code given below :
- A.I, II, III and IV
- B.II, III and IV only
- C.I, III and IV only
- D.I and II only
Correct answer
Explanation
The correct answer is A, I, II, III and IV. All four are parts of the two complex permanent tissues of plants: tracheids and vessels belong to xylem, while sieve tubes and companion cells belong to phloem. A complex tissue is made of more than one type of cell working together for one function. Xylem carries water and minerals upward from the roots and has four elements: tracheids, vessels, xylem parenchyma and xylem fibres. Phloem carries food made in the leaves to other parts and has four elements too: sieve tubes, companion cells, phloem parenchyma and phloem fibres. Simple permanent tissues, by contrast, such as parenchyma, collenchyma and sclerenchyma, contain only one kind of cell. Option B is wrong because it leaves out companion cells, which are part of phloem. Option C is wrong because it leaves out sieve tubes, the main conducting cells of phloem. Option D is wrong because it leaves out tracheids and vessels of xylem. Exam tip: xylem = tracheids, vessels, xylem parenchyma, fibres; phloem = sieve tubes, companion cells, phloem parenchyma, fibres.
Practice Questions
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- C.Ammonium phosphate
- D.Ammonium sulphate
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- A.12.5 cm
- B.5 cm
- C.2 cm
- D.10 cm
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For an astronomical telescope in normal adjustment the magnifying power equals the focal length of the objective divided by that of the eyepiece, so the eyepiece focal length is 50 ÷ 25 = 2 cm.
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- B.rice and mustard.
- C.vegetables and fruits.
- D.soya bean and milk.
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Read the full explanation →Which one of the following compounds is used in black and white photography?
- A.AgF
- B.AgBr
- C.AgCl
- D.Ag2SO4
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Silver bromide is the light-sensitive compound coated on black and white photographic film and paper, because light breaks it down into tiny grains of silver metal.
Read the full explanation →Which one of the following statements about speed and velocity is correct?
- A.Speed and velocity both are vector quantities.
- B.Speed and velocity both are scalar quantities.
- C.Speed is vector quantity and velocity is scalar quantity.
- D.Speed is scalar quantity and velocity is vector quantity.
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