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What is a sieve-tube element?
a. the sugar-conducting cell found in phloem
b. the widened, perforation-containing, water-conducting cell found only in
c. the nutrient- and water-absorbing cell found in root hairs
d. the nucleated and organelle-rich support cell found in phloem
Introduction:
The plants consist of two important tissues, namely, phloem and xylem. Phloem is responsible for the transfer of organic molecules across different cells in the plants. Sieve-tube cells are the specialized cells that are present in the phloem tissue for the transport of carbohydrates.
Answer to Problem 1TYK
Correct answer:
The sieve-tube cells or the sieve-tube elements are the dead, elongated cells found in the phloem of the angiosperms. These elements carry out the transfer of sugar in the plants.
Explanation of Solution
Explanation/Justification for the correct answer:
Option (a) is given as the cell that is responsible for the conduction of sugars. The sieve-tube elements are the specialized cells involved in the conduction of the sugars in the plants. Carbohydrate (starch) is one such form of sugar. On maturity, they are considered as dead cells due to lack of nucleus. These cells are present in the phloem of the angiosperms. Hence, Option (a) is correct.
Explanation for incorrect answer:
Option (b) is given as the widened, perforation-containing, water-conducting cell found only in angiosperms. The perforation-containing, widened cells that carry out transport of water are known as xylem. So, it is a wrong answer.
Option (c) is given as cells that are found in the root hairs and are responsible for the absorption of water and nutrients. The roots hairs are also known as trichoblasts. The trichoblast is formed from the epidermis layer of the root of the plant. So, it is a wrong answer.
Option (d) is given as the nucleated and organelle-rich cells found in phloem. The nucleated and organelle-rich support cells in the phloem are also known as companion cells. The companion cells are those that transport the sugar to the sieve-tube elements in the leaves from the mesophyll. So, it is a wrong answer.
Hence, options (b), (c), and (d) are incorrect.
Thus, sieve–tube cells represent the class of cells that are specialized for the transportation of sugar in the plants and are found in the phloem.
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Chapter 34 Solutions
BIOLOGICAL SCIENCE
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Biology (MindTap Course List)BiologyISBN:9781337392938Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. BergPublisher:Cengage Learning