Question 1

Question 1How do the roots of plants absorb water?

Accepted Answer

The roots have thin layered, unicellular outgrowths of the epidermis; which are called root hairs. They increase the surface area for absorption of water from the soil. Following are the steps of absorption of water:Water is absorbed by the root hairs by the process of Osmosis. The concentration of water molecules is more in soil as compared to the cell. This causes osmosis to occur, and so water is absorbed by the root hair cells from outside as shown in the given diagram.Water molecules move through osmosis from root hair cells to adjacent cells of the inner tissue.This process continues until water reaches the xylem tissue in the root. Thus, water moves from root hair cells through the root cortex to the xylem in the root.Inside the xylem, water travels upwards from one cell to another against the force of gravity.Below diagrams shows the absorption and movement of water in root cells:

Question 2

Question 4How does the food manufactured in the leaves reach different parts of the plant?

Accepted Answer

The sugar molecules manufactured by the leaves by photosynthesis are transported throughout the plant by phloem. The transport of soluble products of photosynthesis is called translocation. Phloem has cells called sieve tubes which are placed one above the other to form long tubes through which food is transported.

Question 3

Question 5Give two points of importance of transpiration in plants.

Accepted Answer

Two points of importance of transpiration in plants are:Cooling effect — Transpiration from the aerial parts of the plant, cools down the plant surface.Ascent of sap and distribution of minerals — Transpiration results in the development of low water potential in the leaf tissues. Thus, water moves from the xylem tissue to the leaf cells and helps in the ascent of sap. Mineral ions also move up along with water due to the transpiration pull.

Question 4

Question 6Differentiate between macro-nutrients and micro-nutrients with examples.

Accepted Answer

Sl.No.Macro-nutrientsMicro-nutrients1.The minerals that are required in large quantities are called Macro-nutrients.The minerals that are required in small quantities are called Micro-nutrients.2.Their requirement is 0.2 to 0.4% of dry weight of the plant.Their requirement is 0.1 to 0.02% of dry weight of the plant.3.Nitrogen, phosphorous, potassium, sulphur, calcium and magnesium are examples of macro-nutrients.Boron, manganese, chlorine, iron, zinc, copper, nickel and molybdenum are examples of micro-nutrients.

Question 5

Question 2Osmosis and Diffusion

Accepted Answer

Sl.No.OsmosisDiffusion1.The movement of water molecules through a semi-permeable membrane from an area of its higher concentration to an area of its lower concentration is called Osmosis.The movement of salt or mineral molecules from a region of their higher concentration to a region of their lower concentration is called Diffusion.2.It takes place only in a liquid medium.It takes place in any medium such as solid, liquid and gas.3.It requires a semi-permeable membrane.It does not require any semi-permeable membrane.4.It is a slow process.It is comparatively a faster process in gases, slow in liquids.

Question 6

Question 3Diffusion and Active transport.

Accepted Answer

Sl.No.DiffusionActive transport1.It is the movement of molecules or ions of a substance from a region of their higher concentration to a region of their lower concentration.It is the movement of ions of a substance from their lower concentration region to their higher concentration region using energy.2.It is the movement of solute or solvent molecules.It is the movement of ions only (no water).3.No cell energy is needed.Cell energy is needed in the form of ATP.4.It occurs through a non-living permeable membrane.It occurs through a living selectively permeable membrane.

Question 7

Question 7The loss of water vapour through the stomata of the leaves is calledwiltingtranslocationtranspirationtransportation

Accepted Answer

transpirationReason — The loss of water in the form of water vapour through the stomata of leaves and other aerial parts of a plant is called transpiration.

Question 8

Question 8Transpiration occurs through openings in leaves calledporesguard cellstomatabarks

Accepted Answer

stomataReason — Stomata are the openings present on lower side of leaves, through which transpiration as well as gaseous exchange occurs.

Transport of Food and Minerals in Plants

Answer the following in detail

Differentiate between

Tick the most appropriate answer