Mass Flow Hypothesis

Q. Arrange the following five events in a correct order that explains the mass flow of materials in the phloem.
1. Water diffuses into the sieve tube elements.
2. Leaf cells produce sugar by photosynthesis.
3. Solutes are actively transported into the sieve elements.
4. Sugar is transported from cell to cell in the leaf.
5. Sugar moves down the stem.

1. 2 - 4 - 3 - 1 - 5
2. 2 - 4 - 1 - 3 - 5
3. 1 - 2 - 3 - 5 – 4
4. 4 - 2 - 1 - 3 – 5

Q. Which of the following statement substantiates the mass flow hypothesis?
I. Sugar is translocated from sink to source.
II. Glucose is converted to sucrose at the sink.
III. Osmosis enables the movement of sucrose into the sieve tubes, which generates a hypertonic condition in phloem.

1. I and II
2. Only I
3. Only III
4. I, II and II

Q. The translocation of organic solutes in sieve tube members is supported by:

1. Mass flow involving a carrier and ATP
2. P-proteins
3. Cytoplasmic streaming
4. Root pressure and transpiration pull

Q. Bulk flow is achieved due to positive hydrostatic pressure gradient and negative hydrostatic pressure gradient in respectively.

1. root hair and phloem
2. phloem and xylem
3. root hair and xylem
4. leaves and phloem

Q.

What is mass flow?

Q.

In the following question, a statement of assertion is followed by a statement of reason. Mark the correct choice as:
Assertion: Translocation of sugar from source (leaf) to sink is defined as pressure flow hypothesis
Reason: Translocation of the solute is facilitated through living phloem sieve tube cells.

1. If both assertion and reason are true and reason is the correct explanation of assertion.

2. If both assertion and reason are true but reason is not the correct explanation of assertion.

3. If assertion is true but reason is false.

4. If both assertion and reason are false.

Q.

Which of the following is not correct in mass flow hypothesis?

1. The sugar is moved bidirectionally

2. Loading of the phloem sets up a water potential gradient that facilitates the mass movement in the phloem

3. As hydrostatic pressure in the phloem sieve tube increases pressure flow stops and sap is accumulated in phloem

4. The sugar which is transported in sucrose

Q.

The transport of water through xylem and transport of organic substances through phloem are achieved respectively by

1. positive hydrostatic pressure as in the working of a garden hose and negative hydrostatic pressure gradient as a suction through a straw
2. positive hydrostatic pressure as a suction through a straw and negative hydrostatic pressure as the working of a garden hose
3. negative hydrostatic pressure gradient as a suction through a straw and positive hydrostatic pressure gradient as the working of a garden hose.
4. negative hydrostatic pressure as in the working of a garden hose and positive hydrostatic pressure as a suction through a straw

Q. Ernst Munch proposed the

1. pressure flow hypothesis
2. mass flow hypothesis
3. bulk flow hypothesis
4. all the above

Q. Which of the following statements are wrong?
(i) Mass flow of substances inside the plant is the result of pressure differences between the two points
(ii) Diffusion cannot account for long distance movement of water and solutes in plants
(iii) Movement through apoplast does not involve crossing the cell membrane
(iv) The movement of water through endodermis is only through symplast

1. none
2. (iii)
3. (ii)
4. (i)

Q.

Define turgidity and turgor pressure.

Q.

How sieve tubes manage to be living?

Q. Ernst Munch proposed the

1. pressure flow hypothesis
2. mass flow hypothesis
3. bulk flow hypothesis
4. all the above

Q.

Sieve tubes are characterised by:

1. Perforated oblique septa

2. Absence of septa

3. Perforated longitudinal walls

4. Simple oblique septa

Q. Leptome is the name of

1. Outer part of bark
2. Living part of bark
3. Phloem
4. Conducting part of phloem

Q. Following figure shows different transport mechanisms used by a cell. If the circles represents transport proteins then choose the correct option showing type of transport.

1. $$\begin{array}{cccc}\text{Simple diffusion}& \text{Facilitated diffusion}& \text{Primary active transport}& \text{Secondary active transport}\\ 3& 1& 4& 2\end{array}$$
2. $$\begin{array}{cccc}\text{Simple diffusion}& \text{Facilitated diffusion}& \text{Primary active transport}& \text{Secondary active transport}\\ 3& 2& 1& 4\end{array}$$
3. $$\begin{array}{cccc}\text{Simple diffusion}& \text{Facilitated diffusion}& \text{Primary active transport}& \text{Secondary active transport}\\ 3& 4& 2& 1\end{array}$$
4. $$\begin{array}{cccc}\text{Simple diffusion}& \text{Facilitated diffusion}& \text{Primary active transport}& \text{Secondary active transport}\\ 4& 0& 4& 1\end{array}$$

Q.

Phages which show a lysogenic cycle are known as

1. Virulent phages

2. Temperate phages

3. Avirulent phages

4. Lytic phages

Q. Suggest an experiment to prove that organic food is translocated through phloem.

Q. (d) How is food transported in plants ?

Q. In plants the translocation of organic solutes take place through

1. Epidermis
2. Xylem
3. Phloem
4. Pith

Q. Assertion :Mass or bulk flow is the movement of substances in bulk from source to sink as a result of pressure differences. Reason: Water, minerals and food are generally moved by mass flow.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect

Q. Which of the following statement substantiates the mass flow hypothesis?
I. Sugar is translocated from sink to source.
II. Glucose is converted to sucrose at the sink.
III. Osmosis enables the movement of sucrose into the sieve tubes, which generates a hypertonic condition in phloem.

1. I and II
2. Only I
3. Only III
4. I, II and II

Q. Osmotic pressure at sink decreases in phloem transport because

1. Sugar is transported through phloem as sucrose
2. Loading of phloem at source sets up a water potential gradient
3. Sugar removed from phloem sap at sink is either utilised to release energy or converted into starch or cellulose
4. Water passes out from phloem sap to the xylem vessel at sink

Q. The translocation of organic solutes in sieve tube members is supported by:

1. Root pressure and transpiration pull
2. P-proteins
3. Mass flow involving a carrier and ATP
4. Cytoplasmic streaming

Q.

Munch hypothesis is based on

1. None of the above

2. Translocation of food due to turgor pressure (TP) gradient and imbibition force

3. Translocation of food due to turgor pressure (TP) gradient

4. Translocation of food due to imbibition force

Q. Which of the following explains bidirectional transport of solutes in phloem tissue

1. Mass flow hypothesis
2. Transcellular strands hypothesis
3. All of these
4. Electro-osmotic hypothesis

Q. Long distance transport of substance from the sites of production or absorption to the sites of storage takes place by

1. Mass flow

2. All of these

3. Diffusion

4. Active transport

Q. Is erythrocytes and sieve tube cell of vascular plant are living or not why?

Q. If the rate of translocation of food is slow, what will be the effect on photosynthesis?

1. It will increase
2. It becomes double
3. It will remain same
4. It will decrease

Q. Movement of food and other materials through vascular tissues of plants is

1. Transpiration
2. Transcription
3. Transduction
4. Translocation