Transport In Plants Test 1 12/11/12

2.

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

Cytoplasmic streaming
Root pressure and transpirational pull
P-proteins
Mass flow involving a carrier and ATP

Correct Answer

A. P-proteins

Explanation

P-proteins support the translocation of organic solutes in sieve tube members. P-proteins, also known as phloem proteins, are found in the sieve tube elements of the phloem tissue. They form a network of filaments that help regulate the movement of solutes through the sieve tubes. P-proteins can block the sieve plate pores, preventing the backflow of solutes, and also aid in sealing damaged sieve tubes. Therefore, P-proteins play a crucial role in facilitating the mass flow of organic solutes in the phloem.

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3.

The continuous column of water in vessel and tracheids during the ascent of sap does not usually get broken because of:

Weak gravitational pull
Transpirational pull
Lignified thick walls
Cohesion and adhesion

Correct Answer

A. Cohesion and adhesion

Explanation

The continuous column of water in the vessel and tracheids during the ascent of sap does not usually get broken because of cohesion and adhesion. Cohesion refers to the attraction between water molecules, causing them to stick together. Adhesion refers to the attraction between water molecules and the walls of the vessels and tracheids. These two forces work together to create a continuous column of water, allowing it to be pulled up through the plant without breaking. The weak gravitational pull, transpirational pull, and lignified thick walls also play a role in the ascent of sap, but they do not directly prevent the column of water from breaking.

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4.

Guard cells help in:

Transpiration
Guttation
Fighting against infection
Protection against grazing

Correct Answer

A. Transpiration

Explanation

Guard cells help in regulating the opening and closing of stomata, which are small openings on the surface of leaves. By controlling the opening and closing of stomata, guard cells regulate the exchange of gases, such as carbon dioxide and oxygen, as well as the loss of water vapor through transpiration. Transpiration is the process by which plants release water vapor into the atmosphere. Therefore, guard cells play a crucial role in facilitating transpiration.

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5.

The guard cells differ from other epidermal cells of the leaf in having:

Mitochondria
Lysosomes
Chloroplasts
Endoplasmic reticulum

Correct Answer

A. Chloroplasts

Explanation

Guard cells are specialized cells found in the epidermis of leaves that regulate the opening and closing of stomata. Stomata are small pores on the leaf surface that allow for gas exchange. Chloroplasts are responsible for photosynthesis, the process by which plants convert sunlight into energy. The presence of chloroplasts in guard cells allows them to produce energy through photosynthesis, enabling them to actively control the opening and closing of stomata in response to environmental cues such as light intensity and water availability.

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6.

Guttation is the result of:

Diffusion
Transpirational pull
Osmosis
Root pressure

Correct Answer

A. Root pressure

Explanation

Guttation is the process by which water is excreted in liquid form from the tips of leaves, usually occurring during the night or early morning. This phenomenon is caused by root pressure, which is the force generated by the roots of plants to push water and dissolved nutrients up through the xylem vessels. As the roots absorb water from the soil, the excess water accumulates in the plant and is forced out through specialized structures called hydathodes, resulting in guttation. Diffusion, transpirational pull, and osmosis are not directly responsible for guttation.

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7.

When beet root cylinders are washed and placed in cold water, anthocyanin does not come out. This indicates that most likely plasma membrane is:

Permeable to anthocyanin
Impermeable to anthocyanin
Differentially permeable to anthocyanin
Dead structure

Correct Answer

A. Impermeable to anthocyanin

Explanation

When beet root cylinders are washed and placed in cold water, if anthocyanin does not come out, it indicates that the plasma membrane is impermeable to anthocyanin. This means that the anthocyanin molecules are unable to pass through the plasma membrane and diffuse into the surrounding water. This suggests that the plasma membrane acts as a barrier and prevents the movement of anthocyanin molecules.

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8.

If the plant cell is immersed in water, the water continues to enter the cell until the _____

Concentration of salts is the same inside the cell as outside
Cell bursts
Diffusion pressure deficit is the same inside the cell as outside
Concentration of water is the same inside the cell as outside

Correct Answer

A. Concentration of water is the same inside the cell as outside

Explanation

When a plant cell is immersed in water, water molecules move into the cell through osmosis. Osmosis is the movement of water from an area of higher concentration to an area of lower concentration across a semi-permeable membrane. As water continues to enter the cell, it will keep moving into the cell until the concentration of water inside the cell is the same as outside. This is because osmosis will continue until equilibrium is reached, where the concentration of water is equal on both sides of the cell membrane.

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9.

Cohesion tension theory operates in _______.

Passive absorption
Active absorption
Both 1 and 2
None of these

Correct Answer

A. Passive absorption

Explanation

The cohesion tension theory explains how water is transported in plants through passive absorption. This process relies on the cohesive properties of water molecules and the tension created by transpiration pull. As water evaporates from the leaves, it creates a negative pressure that pulls water up through the xylem vessels. This theory does not involve active absorption, which would require energy expenditure by the plant. Therefore, the correct answer is passive absorption.

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10.

Rate of water absorption can be increased through ______.

Decreased transpiration
Decreased ion absorption
Increased photosynthesis
Increased transpiration

Correct Answer

A. Increased transpiration

Explanation

Increasing transpiration can increase the rate of water absorption in plants. Transpiration is the process by which water is lost from the leaves through small openings called stomata. When transpiration is increased, more water is drawn up from the roots to replace the water lost through the leaves. This increased flow of water through the plant helps to enhance the rate of water absorption.

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Transport In Plants Test 1 12/11/12

Stomata of a plant open due to:

Quiz Preview

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

The continuous column of water in vessel and tracheids during the ascent of sap does not usually get broken because of:

Guard cells help in:

The guard cells differ from other epidermal cells of the leaf in having:

Guttation is the result of:

When beet root cylinders are washed and placed in cold water, anthocyanin does not come out. This indicates that most likely plasma membrane is:

If the plant cell is immersed in water, the water continues to enter the cell until the _____

Cohesion tension theory operates in _______.

Rate of water absorption can be increased through ______.