Biology

Plant Transport and Physiology

1,834 Questions

Access a comprehensive set of questions on plant transport mechanisms and physiological adaptations. Topics include water movement, translocation of food, and plant responses to external stimuli. These biology questions are essential for medical entrance exams and other science competitive tests.

Xylem and phloem transportTranspiration and evaporationPlant adaptationsGeotropic and phototropic responsesWater absorption by rootsRespiration in roots

Plant Transport and Physiology Questions

Multiple choice biology transport in plant transport in the phloem of plants vascular tissue permanent tissue

Loading of phloem means

  1. Elongation of phloem cells

  2. Separation of phloem parenchyma

  3. Strengthening of phloem fibres

  4. Pouring of sugar into phloem
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Loading of phloem is a process of loading carbon into the phloem for transport to different sinks in a plant. Sinks include metabolism, growth, storage and other processes or organ that need carbon solutes to persist.

So, the correct answer is 'Pouring of sugar into phloem'.

Multiple choice biology transport in plant transport in the phloem of plants vascular tissue permanent tissue

Radioactive tracer studies with $^{14}$C have shown that

  1. Phloem transports organic nutrients

  2. Phloem transports inorganic nutrients

  3. Xylem transports inorganic nutrients

  4. Xylem transports organic nutrients
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The radioactive tracer is a chemical compound used to determine the atoms and molecules by the virtue of radioactive decay. The age of a tree, transportation of solute through phloem etc is seen through the use of radioactive of carbon. 

So, the correct answer is 'Phloem transports organic nutrients'.

Multiple choice biology transport in plant transport in the phloem of plants vascular tissue permanent tissue

A column of water within xylem vessels of tall trees does not break under its weight because of 

  1. Dissolved sugar in water

  2. Tensile strength of water

  3. Lignification of xylem vessels

  4. Positive root pressure
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Positive root pressure pushes up the water. 

Lignification of xylem vessels provide mechanical support.
Dissolved sugar in water reduces it's water potential but has no role in maintaining a column.
Tensile strength of water is its ability to resist the break in column due to forces like the transpiration pull. This is achieved by properties of water like Cohesion and Adhesion.
So the correct answer is 'Tensile strength of water'.

Multiple choice biology transport in plant transport in the phloem of plants vascular tissue permanent tissue

Unidirectional flow of water, minerals, some organic nitrogen and hormones occurs through

  1. Xylem

  2. Phloem

  3. Root

  4. Vascular tissue
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
There are two types of vascular tissues in plants, xylem and phloem, xylem translocation is mainly from roots to aerial parts. It passes water with mineral salts, some organic nitrogen and hormones. Phloem translocates organic substances and some inorganic solutes first from leaves to all other parts of the plant and storage organs. Storage organs reexport organic nutrients to those parts which require the same, such as newly formed leaves and fruits.
So, the correct answer is 'Xylem'.
Multiple choice biology transport in plant transport in the phloem of plants vascular tissue permanent tissue

Ringing/girdling experiments demonstrate

  1. Phloem is responsible for translocation of food

  2. Xylem is responsible for ascent of sap

  3. Transpiration pull

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

Ringing/Girdling experiments demonstrate that phloem is responsible for translocation of food because phloem is present outside to xylem so when a ring of bark is removed from a woody plant, the woody xylem part remains intact, water and nutrient reaches the leaves. After the preparation of the photosynthate, it is not transported to other parts below the girdle since the phloem part is removed. This experiment shows that the phloem tissue aids food transport.

So, the correct option is A.

Multiple choice biology transport in plant transport in the phloem of plants vascular tissue permanent tissue

State an incorrect statement w.r.t. phloem transport 

  1. Translocation is variable so transport is unidirectional

  2. Translocation of sucrose and water occurs through companion cells only

  3. Phloem sap is slightly alkaline

  4. Phloem is cutout to prove its role in translocation during girdling experiment
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Xylem flow is unidirectional and phloem flow is bidirectional because xylem transport water from soil to leaves and phloem transfers the food.

Multiple choice biology transport in plant transport in the phloem of plants vascular tissue permanent tissue

Food is transported to different parts of plant through

  1. Xylem

  2. Phloem

  3. Pith

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

In plant transport system no heart, no blood, and no other circulatory system, but plants do need a transport system to move food, water, and minerals around. They use two different systems then xylem moves water and solutes from the roots to the leaves and phloem moves food substances from leaves to the rest of the plant, then phloem is the transporting system of food to the plants.

So, the correct option is B.

Multiple choice biology transport in plant transport in the phloem of plants vascular tissue permanent tissue

Choose the correct answers from the alternatives given.
Which of the following tissues transports water and nutrients within the plant?

  1. Epidermal tissue

  2. Ground tissue

  3. Meristem

  4. Vascular tissue
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Xylem is the chief water and nutrients conducting tissues of the plants. These xylem tissues form the part of vascular tissues. These conduct water and nutrients from the roots to the top of the plants i.e. to the stem and the leaves. Along with acting as a conducting tissue, xylem also provides the mechanical strength to the plant parts.

Hence, the correct answer is 'Vascular tissue'.

Multiple choice biology transport in plant transport in the phloem of plants vascular tissue permanent tissue

The phenomenon of osmosis is involved in the diffusion of water from

  1. One cell to another

  2. Soil to root

  3. Xylem vessel to xylem vessel

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

Osmosis is the process of flow of fluid from higher to lower concentration through the semi-permeable membrane. The wall of xylem vessels behaves as the semi-permeable membrane so diffusion of water from one xylem vessel to another xylem vessel can be called the phenomenon of osmosis.

In all other three cases, there is no presence of semi-permeable membrane so, it is the simple diffusion process.
So, the correct answer is the 'xylem vessel to xylem vessel'.

Multiple choice biology transport in plant transport in the phloem of plants vascular tissue permanent tissue

........ conducts water and ions whereas ........ conducts food.

  1. Phloem; xylem

  2. Xylem; phloem

  3. Cambium; phloem

  4. Xylem; cambium
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Vascular tissues help in transportation such as xylem and phloem. The xylem carries water and dissolved ions from the root to stem and leaves and phloem carry dissolved sugar from the leaves to all other parts of the plants. So, the correct answer is "xylem; phloem.
Multiple choice botany internal structure of root, stem and leaf internal structure of monocot leaf internal structure of dicot leaf internal structure of leaf (dicot and monocot)

In floating leaved plants stomata occur on

  1. Lower surface

  2. Upper surface

  3. Both surfaces

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

Stomata is a pore, found in the epidermis of leaves, used to control gas exchange. The pore is bordered by a pair of specialized parenchyma cells, known as guard cells that are responsible for regulating the size of the opening. Stomata are present in the sporophyte generation of all land plant groups except liverworts. 

Dicotyledons usually have more stomata on the lower epidermis than the upper epidermis. 
In plants with floating leaves, stomata may be found only on the upper epidermis and submerged leaves may lack stomata entirely.

Multiple choice botany internal structure of root, stem and leaf internal structure of monocot leaf internal structure of dicot leaf internal structure of leaf (dicot and monocot)

The lower surface of leaf will have more number of stomata in a __________.

  1. Dorsiventral leaf

  2. Isobilateral leaf

  3. Both (a) and (b)

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

Transpiration is the evaporative loss of water by plants. It occurs mainly through the stomata in the leaves. Usually the lower surface of a dorsiventral (often dicotyledonous) leaf has a greater number of stomata while in an isobilateral(often monocotyledonous) leaf. There are almost equal number of stomata on both surfaces.

Multiple choice botany internal structure of root, stem and leaf internal structure of monocot leaf internal structure of dicot leaf internal structure of leaf (dicot and monocot)

In dorsiventral leaves stomata occur

  1. More on upper palisade containing surface and less on spongy parenchyma containing lower surfac

  2. Fewer on upper surface and more on lower surface

  3. Equally on both

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

In dorsiventral leaves, less stomata are present in the upper epidermis and more stomata are present on the lower epidermis.

So, the correct option is ‘Fewer on upper surface and more on lower surface’.