Absorption By Roots

Front 1

What is plant physiology?

Back 1

Plant physiology is the branch of biology which deals with the life functions of the plant. It includes the functioning of cells, tissues, organs, organ systems and the organism as a whole.

Front 2

What are the functions of the root?

Back 2

1. The roots fix the plant in the soil giving it support.

2. the roots absorb water and mineral nutrients from the soil and conduct them into the stem for supply to leaves, flowers, fruits exactra.

Front 3

What are the purposes of water and minerals for plants?

Back 3

1. Photosynthesis: water is used up in the Green Leaves as a raw material in the synthesis of glucose. 2. Transpiration: a large quantity of water gets evaporated as water vapour during transpiration, for cooling in hot weather, for producing suction force, exactra 3. Transportation: transportation of substances in water solution from Roots upwards into the shoot or from leaves to the other parts. 4. Mechanical stiffness: water provides turgidity, which is necessary for stiffness of plant tissues.

Front 4

Name the nutrients that are absorbed as salts.

Back 4

Nitrates, phosphates, sulphates potassium, calcium, magnesium, chlorine and exactra

Front 5

Why does the root hairs contain cell sap of higher concentration than the surrounding water?

Back 5

Root hairs are extensions of outer cells of roots. They also contain large vacuoles which are filled with a solution called cell sap. Some salt are dissolved in the cell sap, which makes the concentration higher than that of the surrounding water. This results in the the movement of water from the outside to the inside .

Front 6

Define cell wall & cell membrane.

Back 6

The root hairs have 2 outer layers - ° The cell wall is thin and permeable. It allows the movement of water molecules and dissolved substances freely in and out of the cell.

° The cell membrane is very thin, and is semi-permeable, which means that it allows water molecules to passing through, but not the larger molecules of the dissolved salts.

Front 7

What are the mains 5 by which water is conducted from soil by the roots?

Back 7

1. Imbibition 2. Diffusion 3. Osmosis 4. Active transport 5. Turgidity and flaccidity

Front 8

What is imbibition?

Back 8

Imbibition is a phenomenon by which the living or dead plant cells absorb water by surface attraction.

Front 9

What is diffusion?

Back 9

Diffusion is the free movement of molecules of a substance from the region of their higher concentration to the region of the lower concentration when the two are in direct contact.

Front 10

Define osmosis.

Back 10

Osmosis is the movement of water molecules from their region of higher concentration to the region of lower concentration through a semipermeable membrane.

Front 11

What is active transport?

Back 11

Active transport is the passage of a substance from its lower to higher concentration through a living cell membrane using energy from the cell.

Front 12

What is passive transport?

Back 12

Passive transport is nothing distance from diffusion. "Passive" message to requiring no input of energy. There is a free movement of molecules from their higher concentration to lower concentration.

Front 13

What is osmotic pressure?

Back 13

It is the minimum pressure that must be exerted to prevent the passage of the pure solvent into the solution when the two are separated by a semipermeable membrane.

Front 14

Define tonicity.

Back 14

Relative concentration of the solution that determine the direction and extent of diffusion is called tonicity.

Front 15

What is a isotonic solution?

Back 15

The relative concentration of water molecules and the solute on either side of the cell membrane is same . In such solution there is no movement of water molecules across the cell membrane. Therefore no osmosis takes place.

Front 16

What is hypotonic solution?

Back 16

In this condition, the solution of side the cell has lower concentration then fluid inside the cell. Therefore, water molecules from outside will move into the cell which results in endosmosis.

Front 17

What is hypertonic solution?

Back 17

In this condition, the solution after the cell has higher concentration than the fluid inside the cell. Therefore the water molecules from the interior of the cell will move out which results in exosmosis .

Front 18

What is turgidity?

Back 18

When a cell reaches a state where it cannot accommodate any more water, it is fully distended, it is called turgid and the condition is called turgidity.

Front 19

What is plasmolysis?

Back 19

Plasmolysis is the contraction of cytoplasm from the cell world caused due to the withdrawal of water when placed in a strong solution.

Front 20

What is flaccidity?

Back 20

What is the condition in which the cell content is shrunken and the cell is no more tight. The cell is then said to be flaccid.

Front 21

Why certain nutrients cannot pass through the cell membrane of the root cells?

Back 21

Nutrients like nitrates, sulphates, potassium, zn, manganese, exactra. Cannot pass through cell membrane of the root cells easily. This is because their concentration is higher inside the root cells, and it is so maintained in order to develop osmotic pressure for absorbing water. In this way, the concentration gradient of these ions is opposite to that of the diffusion.

Front 22

Define taaja pressure.

Back 22

When a cell is turgid, its wall is stretched under pressure from inside, and in it turn, it presses the cell contents towards the centre of the cell . The pressure of the cell contents on the cell wall is called the pressure.

Front 23

What is wall pressure?

Back 23

The pressure exerted by the cell wall on the cell content is called wall pressure.

Front 24

What is guttation?

Back 24

Water appears as tiny drops along the margins for the tips of the leaves, especially in the early mornings. This loss of excessive water is called guttation.

Front 25

What do you mean by capillarity?

Back 25

Capillarity of xylem vessels causes the water from the lower level to rise to fill up the vacuum created by the loss of water due to transpiration from the leaves. The diameter of the tube, greater will be the height of The water rising in it ignoring a force called capillary force.

Front 26

What is is transpiration pull?

Back 26

As the water is lost from the leaves surface by transpiration, more water molecules are pulled up due to the tendency of water molecules to remain joined and thus to produce a continuous column of water through the stem.

Front 27

What is adhesion?

Back 27

Is causes the water to stick to the surface of the cells does drawing more water molecules from the below when the leaves cells lose water during transpiration. This pulling force or suction force provided by the leaves is especially important in tall trees like pines which do not have enough root pressure.

Front 28

What is Cohesion?

Back 28

Cohesion is the molecular attraction by which the particles of the body are united throughout the mass.