Tag: biology

Questions Related to biology

Root pressure is retarded or become absent in

biology absorption by roots - the processes involved root pressure transportation in plants factors affecting the transport of water and minerals in plants

  1. Starvation

  2. Low temperature

  3. Drought

  4. All

Show answer
Correct Option: D
Explanation:

Root pressure is retarded or become absent under conditions of starvation, low temperature, drought and reduced availability of oxygen.

Root pressure can be demonstrated by means of 

biology absorption by roots - the processes involved root pressure transportation in plants factors affecting the transport of water and minerals in plants

  1. Wilting

  2. Guttation

  3. Transpiration

  4. Exudation/bleeding

Show answer
Correct Option: D
Explanation:

Root exudates function in below ground plant defence. Plant roots are constantly exposed to a variety of natural enemies, including pathogenic microorganisms and root-feeding arthropods. These organisms inhabit the soil surrounding the root system, which is designated the rhizosphere. 

Chemicals secreted into the soil by roots are referred to as root exudates. By doing this root changes the chemical and physical property of soil and inhibit the growth of other plant species. Root pressure can be demonstrated by means of exudation or bleeding caused due to root pathogens.

so the correct answer is 'Exudation'.

Choose the correct answers from the alternatives given.
Root pressure can be measured by

biology absorption by roots - the processes involved root pressure transportation in plants factors affecting the transport of water and minerals in plants

  1. Osmometer

  2. Potometer

  3. Manometer

  4. Porometer

Show answer
Correct Option: C
Explanation:

Different processes can be measured by various apparatus.

A. Osmometer is used to measure osmotic pressure (pressure needed to stop the solvent to pass through the semi-permeable membrane).
B. Potometer is used to measure transpiration rate (the rate at which transpiration occurs).
C. Manometer is used to measure the root pressure (pressure that is exerted by roots such that it allows sap to rise through the plant stem to the leaves).
D. Porometer is used to measure stomatal conductance in leaves.
Hence, the correct answer is 'Manometer'.

Water from soil enters into root hairs owing to

water potential water potential and pressure plant water relation transport in plants biology

  1. Atmospheric pressure

  2. Capillarity

  3. Root pressure

  4. Osmotic pressure or diffusion

  5. Turgor pressure

Show answer
Correct Option: D
Explanation:

Osmotic pressure of the cell sap of root hairs is usually higher than the osmotic pressure of the soil water. Therefore, the diffusion pressure deficit (DPD) and the suction pressure in the root hairs become higher and water form the cell wall enters into then through the plasma membrane by osmotic diffusion.

In simple osmotic system, at-constant temperatures, the water potential results from the combined but opposite actions of _______________.

water potential water potential and pressure plant water relation transport in plants biology

  1. Relative humidity and pressure potential

  2. Pressure potential and saturation vapour potential

  3. Saturation vapour pressure and osmotic potential

  4. Osmotic potential and pressure potential

Show answer
Correct Option: A

As the glomerular filtrate courses the tubules, its composition and osmotic concentration changes, due to tubular reabsorption. Which of the following is incorrect match regarding the segment of nephron and osmotic concentration of filtrate?

water potential water potential and pressure plant water relation transport in plants biology

  1. Segment of nephron -Proximal convoluted tubule Osmotic concentration of filtrate- Isotonic to blood plasma

  2. Segment of nephron -Descending limb of Henle's loop Osmotic concentration of filtrate- Hypertonic

  3. Segment of nephron -Ascending limb of Henle's loop Osmotic concentration of filtrate- Hypotonic

  4. Segment of nephron -Bowman's capsule Osmotic concentration of filtrate- Hypotonic

Show answer
Correct Option: A

Which of the following statements is correct?

water potential water potential and pressure plant water relation transport in plants biology

  1. Bacteria do not survive in salted pickles because they get plasmolysed in hypertonic medium

  2. Osmotic potential is numerically equal to the osmotic pressure but is negative in sign

  3. Kneading of wheat flour is accompanied by release of heat which is due to imbibition

  4. All of these

Show answer
Correct Option: D
Explanation:

Following are the correct statements:

(1) Bacteria do not survive in salted pickles because they get plasmolysed in hypertonic medium.
(2) Osmotic potential is numerically equal to the osmotic pressure but is negative in sign.
(3) Kneading of wheat flour is accompanied by the release of heat which is due to imbibition.
So, the correct answer is (d).

Choose the correct answers from the alternatives given :
In which one of the following processes the phenomenon of osmosis is not involved

water potential water potential and pressure plant water relation transport in plants biology

  1. Water entering a mesophyll cell from xylem vessel element

  2. Water passing from root hair to adjacent cells

  3. Water from soil entering a root hair

  4. Water passing up a xylem vessel element to xylem vessel above it

Show answer
Correct Option: D
Explanation:

Osmosis is the movement of solvent from its higher concentration to its lower concentration across a semipermeable membrane. Movement of water through xylem element to xylem vessels above it occurs due to the cohesive force between the water molecules, suction pressure and transpiration pull.


So the correct answer is "Water passing up a xylem vessels element to xylem vessel above it".

Fastest phase of S-shaped growth curve is

biology plant growth growth rates and conditions for growth population ecology growth and development

  1. Lag phase

  2. Log Phase

  3. Stationary phase

  4. Both (a) and (B).

Show answer
Correct Option: B
Explanation:

  • S-shaped logistic growth curve includes 3 phases:
  • Lag phase - When some organisms are introduced in an area, the population growth begins slowly.
  • Log phase - The conditions are ideal and the maximum growth rate is reached.
  • Stationary phase - Growth rate begins to slow down as factors such as food, water and space become limiting.
Thus, the correct answer is 'Log phase.'

Most realistic growth curve is

biology plant growth growth rates and conditions for growth population ecology growth and development

  1. J-shaped

  2. Sigmoid

  3. Parabolic

  4. Both (A) & (B)

Show answer
Correct Option: B
Explanation:

The resources for the growth of most animal population are finite and become limiting sooner or later, thus the logistic growth model is considered more realistic. The equation for model gives a sigmoid shaped graph when plotted against the N in relation to time.  The equation is :

dN/dT=rN(K-N/K) 
where, 
N is Population density at time t
r is the intrinsic rate of natural increase 
K is carrying capacity.
So, the correct answer to the question is 'Sigmoid'.