Tag: botany

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Multiple choice botany plant water relation diffusion pressure deficit other pressure components osmosis in plants

When a plasmolysed cell is placed in a hypotonic solution then water will move inside the cell this will happen due to which force?

  1. Diffusion Pressure Deficit

  2. Osmotic Pressure

  3. Wall Pressure

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
When a plant cell is placed in hypotonic solution, water enters into a cell by osmosis and as a result turger pressure develops. The cell membrane get stretched and osmotic pressure of cell decreases. As cell absorbs more and more water its Total Pressure increases and Osmotic Pressure decreases. When a cell is fully turgid, its OP is equal to TP and DPD is zero. Turgid cells cannot absorb any more water. Thus, with reference to plant cell, the DPD can be described as actual thirst of cell for water and can be expressed as DPD=OP-TP.

When DPD is zero, entry of water will stop. Thus it is DPD that tends to equate and represents water absorbing ability of a cell, it is also called suction force (SF) or suction pressure (SP).
The term diffusion pressure deficit (DPD) was coined by B.S Meyer in 1938. Originally DPD was described as suction pressure by Renner (1915). It is reduction in the diffusion pressure of water in solution or cell over its pure state due to presence of solutes in it and forces opposing diffusion.
DPD of a solution is equal to its osmotic pressure i.e. DPD = OP(of solution). DPD of a cell is influence by both osmotic pressure and wall pressure (turgor pressure) which opposes the endosmotic entry of water, i.e. DPD = OP - Wall pressure. DPD is directly proportional to the concentration of the solution. DPD decreases with dilution of solution. The actual pressure with which cell absorbs water is called "suction pressure".

Osmotic Potential - The potential of water molecules to move from a hypotonic solution (more water, less solutes) to a hypertonic solution (less water, more solutes) across a semi permeable membrane.
Water potential (Symbol Ψ). The difference between the chemical potential of the water in a biological system and the chemical potential of pure water at the same temperature and pressure. It is manifested as a force acting on water molecules in a solution separated from pure water by a membrane that is permeable to water molecules only and can be expressed as the sum of the solute potential and the pressure potential: Ψ = Ψs + Ψp 
Multiple choice botany plant water relation diffusion pressure deficit other pressure components osmosis in plants

A and B are contiguous cells. A has osmotic pressure (OP) = 10 atm. Turgor pressure (TP) = 7 atm and Diffusion pressure deficit (DPD) = 3atm. B has OP = 8 atm, TP = 3 atm, DPD = 5 atm. The direction taken by the water would be

  1. No movement of water

  2. Equilibrium between the two

  3. Movement of water from A to B

  4. Movement of water from B to A
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Movement of water from A to B since water flows in the direction from low DPD to high DPD.  'A' cell has lower DPD than 'B' so the movement of water from A cell to B cell will be the correct answer.

Multiple choice botany plant water relation diffusion pressure deficit other pressure components osmosis in plants

In a plant cell DPD is zero when it is 

  1. Plasmolysed

  2. Turgid

  3. Flaccid

  4. Incipient
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A cell is fully turgid means it is full of water i.e, it cannot absorb any more water. In a fully turgid cell DPD (Diffusion Pressure Deficit) is zero and the net movement of water into the cell stops satisfying the equation  DPD =  OP +  TP. Therefore, for the fully turgid cells has DPD is zero satisfying osmotic pressure (OP) and turgor pressure (TP) must be equal, when a cell absorbs more and more water turgor pressure increases thereby it will be positive value and osmotic pressure decreases hence it is negative value.

So, the correct answer is option B.

Multiple choice botany plant water relation diffusion pressure deficit other pressure components osmosis in plants

Arrange root hair cell, inner cortical cell and mesophyll cell in ascending order of DPD.

  1. Mesophyll cell, root hair cell and cortical cell

  2. Cortical cell, mesophyll cell, and root hair cell

  3. Root hair cell, cortical cell and mesophyll cell

  4. Root hair cell, mesophyll cell and cortical cell
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

DPD means deficit pressure diffusion. Roots absorb water through root hairs. For the absorption of water, there should be a concentration gradient between root hair and soil.

Root hair cells are creating concentration gradient and these are absorbing so water amount is more in this region so DPD is less. Cortical cells are present in the stem region so the amount of water is somewhat less in this region and DPD is more.
Mesophyll cells are present in leaves so here the amount of water is less and DPD is more and highest in this region.
So, the correct answer is 'Root hair cell, cortical cell and mesophyll cell'.

Multiple choice botany fibre to fabric: plant fibre classification of fibres fibres history of fabric

Which of the following is considered as animal fibre?

  1. Alpaca fibre and mohair

  2. Silk and fur

  3. Alpaca and angora

  4. All of them
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Animals fibres are those which largely consists protein. Some of the animals have the property to provide such kind of father or fur which can be used to produce wool. All the given examples are animal fibre use to form a different type of wool.

Multiple choice botany fibre to fabric: plant fibre classification of fibres fibres history of fabric

The rearing of silkworms to obtain silk is called __________:

  1. Sericulture

  2. Horticulture

  3. Agriculture

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
$A$
In sericulture,silkworms are cultivated to produced silk. Although there are several commercial species of silkworms, Bombyx Mori (the caterpillar of the domesticated silk moth) is the most widely used and intensively studied silkworm. Silk was first produced in China as early as the Neolithic period.