Tag: botany

Quizzes (264) Questions (5276)

Questions Related to botany

Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

Ascent of sap will be maximum during

  1. Daytime

  2. Night time

  3. Early morning

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Cohesion transpiration pull theory was put forward by Dixon and Jolly in 1894. It is also known as Dixon's theory of ascent of sap. During day time, there will be maximum water loss due to transpiration, hence, transpiration pull will also be maximum during day time. Consequently, maximum ascent of sap will occur during day time.

Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

The rate of transpiration ........... the process of ascent of sap.

  1. Increases

  2. Decreases

  3. Do not affect

  4. Increases and then decreases
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Transpiration causes the development of a pull or a negative pressure region which created a suction force to aid the ascent of sap. It increases the process of ascent of sap.

So the correct answer is 'Increases'.

Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

The root pressure theory considers ........... responsible for the ascent of sap.

  1. Gravitational pull

  2. Hydrostatic pressure

  3. Capillary force

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The root pressure theory considers that hydrostatic pressure developed in the roots is responsible for pushing the water through the column. It depends on the active accumulation of minerals in the root cells which then causes passive absorption of water creating a high pressure.

It neglects the effect of gravity.
Capillary force is not the driving force in this theory.
Many small herbaceous plants only depend on root pressure for ascent of Sap.
So the correct answer is ' Hydrostatic pressure'.

Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

Organic and mineral nutrients undergo______

  1. Unidirectional

  2. Bidirectional

  3. Multidirectianal

  4. Both A and B
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Organic material in plants is transferred by phloem while water and mineral nutrients are transferred by xylem. It is a well-known fact that xylem only has unidirectional transport of water while phloem can exhibit bidirectional transport.

So, the correct answer is 'Both A and B'.

Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

Pulsation theory was proposed by

  1. Godlewski

  2. Jagadish Chandra Bose

  3. Dixon and Joly

  4. Arthur
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Sir J.C. Bose proposed a theory of ascent of sap known as pulsation theory. The pulsation theory states that water is absorbed by the plants due to the metabolic activity of living cells which are in constant state of rythmatic pulsation. But it was not accepted as water can be passively absorbed by the roots even the cells were dead.
So, the correct answer is option B.
Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

Which substances do the plants obtain from the soil for the constitution of the body?

  1. Organic substances

  2. Inorganic substances

  3. Complex substances

  4. Insoluble substances
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Soil contains a large number of inorganic substances in the form of ions which are taken up by the plant through process called ascent of sap
So, the correct answer is 'Inorganic substances'
Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

Theory of 'Ascent of Sap' was given by Dixon and Jolly. Which of them is against the theory?

  1. Cohesive and adhesive properties of H$ _2$O

  2. Requirement of ATP

  3. Presence of pores in the tracheary elements

  4. All of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Ascent of sap theory is based on transpiration pull of a continuous water column in the xylem elements of plants. The continuous water column is generated because of adhesion and cohesion forces, operating between water molecules and xylem elements and between water molecules respectively. The pull is generated passively due to loss of water during transpiration and does not requires input of energy. Hence, there is no requirement of ATP in ascent of sap and it is a physical process only.

Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

First theory for ascent of sap was proposed by

  1. Westermeier

  2. Godlewski

  3. Bose

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

The first theories proposed to explain ascent of sap were Vital force theories. These theories believed that living cells are involved in the ascent of sap, e.g., relay pump theory by Godlewski, 1883 and Pulsation theory by Bose, 1923.  

Bose believed that the inner most cortical cells pump water into the interior that contains xylem channels. The vital force theories have been discarded because as proved by Boucherie in 1840 and Strasburger in 1891 water rises up the stem even when all the living cells are killed by poison or heat.