Dear students, prepare for biology class 9th chapter 9 long questions. These important long questions are carefully added to get you best preparation for your 9th class biology ch. 9 exams.
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Question: 1
Describe how water and ion uptake occurs in plants?
Answer: 1
1-20. Introduction:
In addition to anchoring the plant, roots perform two other vital functions.
(i) Absorbs water and salts from the soil.
(ii) Secondly, they provide conducting tissues for distributing these substances to the tissues of the stem.
2. Internal Structure of Root
(i) Conducting Tissues
Conducting tissues (xylem and phloem) of root are grouped in the center to form a rod shaped core, which extends throughout the length of the root.
(ii) Pericycle
Outside the conducting tissues, there is a narrow layer of thin walled cells, the pericycle. (iii) Endothermic and Cortex
A single layer of cells, endothermic surrounds the pericycle layer. External to this, there is a broad zone of cortex which consists of large and thin walled cells.
(iv) Epidermis
The cortex is bounded on the outside by a single layer of epidermal cells.
(v) Root Hairs
Roots also have cluster of tiny root hairs, which are actually the extensions of epidermal cells.
Functions of Root Hair:
(i) Large Surface Area for Absorption
Root hairs provide large surface area for absorption. They grow out into the spaces between soil particles where they are in direct contact with the water.
(ii) Absorption and Transport of Water
The cytoplasm of the root hairs has higher concentration of salts than the soil water, so water moves by osmosis into the root hairs. Salts also enter root hairs by diffusion or active transport. After their entry into the root hairs, water and salts travel through inter cellular spaces or through cells (via channels, called piasmodesrnata and reach xylem tissues. Once in xylem, water and salts are carried to all the
aerial parts of plant.
