levels of plant transport system :
2. Transport of water and substances between _.

(a)  

3 levels of plant transport system ;
3. Long-distance transport of sap through xylem and phloem throughout the _.

(a)  

Source :
1. Location/Region of _ and organic solutes synthesis.

(a)  

Source :
2. Organic solutes such as sucrose and amino acids are produced in these photosynthetic tissues and then actively _ into the sieve tubes of the phloem for transport to other parts of the plant.

(a)  

Sink :
1. These include growing _ and root regions, developing flowers and fruits, as well as storage organs such as tubers and bulbs.

(a)  

Sink :
2. In these sink areas, sucrose is _ from the sieve tubes of the phloem to be used or stored.

(a)  

Xylem and transpiration :
1. Plants imbibe and transpire _ water than animals do, as they lack a circulatory system.

(a)  

Xylem and transpiration :
2. Approximately _% of all water absorbed by the roots is lost through the stomata via transpiration, without being used in metabolic processes.

(a)  

Xylem and transpiration :
3. A single plant can transpire about _ liters of water during one growing season.

(a)  

Xylem and transpiration :
4. Water movement in plants occurs due to differences in _ between the soil, root, stem, leaf, and atmosphere.

(a)  

Xylem and transpiration :
5. Under normal conditions, the water potential in the soil is _ than that in the root cell cytosol, causing water to move along this potential gradient.

(a)  

Xylem and transpiration :
6. This movement is called _, and it is the primary force that drives water transport through the xylem.

(a)  

Xylem and transpiration :
7. The aqueous solution of water and dissolved minerals in the xylem is referred to as _.

(a)  

Xylem and transpiration ;
8. Bulk flow is significantly _ than diffusion or osmosis, with a transport rate of 15– 45 moles per hour, depending on environmental conditions and the size of the xylem lumen

(a)  

Xylem and transpiration :
9. In fact, xylem can transport water to heights of up to _ feet in the tallest trees on Earth.

(a)  

Absorption and Transport of Water and Minerals in Plants :
1. Mineral ions are essential for _.

(a)  

Absorption and transport of water and minerals in plants :
2. Solutes generally diffuse _ their concentration gradients.

(a)  

Absorption and transport of water and minerals in plants ;
3. Root hairs increase the surface area for efficient _.


(a)  

Absorption and transport of water and minerals in plants ;
4. The plasma membranes and _ (vacuolar membranes) of root cells contain transmembrane proteins.

(a)  

Absorption and transport of water and minerals in plants ;
5. These proteins function as channels, carriers, or pumps, facilitating the movement of solutes into cells and _ cells throughout the root system.

(a)  

Passive Transport :
1. Osmosis: The diffusion of _ across a selectively permeable membrane.

(a)  

Passive transport :
2. Generally a slow process, unless solutes move through _ or selective channels (e.g., gated channels that open or close in response to environmental stimuli).

(a)  

Active transport :
1. Requires energy (ATP) to move solutes _ their concentration or electrochemical gradient

(a)  

Active transport :
2. Example: The proton pump actively transports H⁺ ions across the membrane, creating a _.

(a)  

Active transport :
3. This _ can then be used to drive other processes, such as nutrient uptake via co-transport mechanisms.

(a)  

Root Pressure : The Upward Push of Xylem Sap

1. Water enters the root because the water potential of root tissues is almost always lower than that of the soil, due to the higher concentration of _ in the roots

(a)  

Apoplast Pathway (Passive diffusion; major route)

1. Water moves through the _ and the spaces between cellulose fibers, bypassing the cell membrane.

(a)  

Apoplast Pathway (Passive diffusion; major route)

2. This pathway allows _ movement of water through the non-living parts of the root.

(a)  

Symplast Pathway (Involves active transport)

1. Water enters the _ of root cells and moves from cell to cell through plasmodesmata—cytoplasmic strands connecting adjacent cells.

(a)  

Symplast Pathway (Involves active transport)

2. Movement follows a _ potential gradient.

(a)  

Vacuolar / Transmembrane Pathway

1. Water moves through the _, cytoplasm, and cell membranes of each cell along its path

(a)  

Vacuolar / Transmembrane Pathway

2. This route involves repeated crossing of plasma membranes and _ (vacuolar membranes).

(a)  

At Night: Root Pressure Mechanism :

1. Stomata are usually (a)   .

At night : Root pressure mechanism

2. The endodermis prevents the leakage of (a)   from the stele back into the surrounding tissues.

At night : Root pressure mechanism

3. This leads to an (a)   of ions in the stele, resulting in a decrease in water potential there.

At night : Root pressure mechanism

4. Consequently, water flows from the cortex into the stele, generating root pressure—a positive pressure that pushes xylem sap upward due to the (a)   from the roots.

At night : Root pressure mechanism

5. This root pressure, exerted from below, creates a positive pressure potential, meaning water potential (a)   as it moves up the stem.

At night : Root pressure mechanism

6. However, (a)   alone is only sufficient to lift water a few feet above the ground and is not the primary mechanism for water transport in tall plants.

Guttation :

1. In small plants, root pressure can lead to a potentially harmful buildup of water pressure at night, when stomata are (a)   .

Guttation :

2. 2. To relieve this pressure, many herbaceous plants possess specialized structures known as (a)   , located along the leaf margins.

Guttation :

3. These openings allow excess water, driven by root pressure, to be exuded from the plant in the form of (a)   , a process known as guttation.

Guttation :

4. 4. The (a)   commonly seen on leaf edges in the early morning (especially under high humidity conditions) are a result of this process.

Guttation :

5. Guttation helps prevent (a)   by relieving internal water pressure during periods when transpiration is minimal.

Characteristics of Root Hairs :
1. (a)   cell walls.

Characteristics of root hairs :
2. Large surface area-to-volume ratio for efficient (a)   of water and minerals

WATER MOVEMENT :
1. Water moves from an area of high water potential in the (a)   to a lower water potential in the root hair

WATER MOVEMENT :
2. Soil → (a)   → Cortical Cell → Cell-to-Cell Movement

WATER MOVEMENT :
3. Water is drawn into the plant primarily by (a)  

WATER MOVEMENT :
4. Root cells actively pump ions (using (a)   ) into their cytoplasm

WATER MOVEMENT :
5. The high ion concentration inside the cells creates a greater (a)   compared to the surrounding soil water.

WATER MOVEMENT :
6. This results in water moving into the (a)   via osmosis.

Apoplast Pathway : Through the cell walls and (a)   (non-living parts)

Symplast Pathway : Through the cytoplasm of cells connected by (a)   .

Vacuolar (Transmembrane) Pathway : Through the vacuoles, cytoplasm, and across (a)  

Shoot tension : The upward pull of xylem sap
1. Water movement in plants occurs not only from below via positive pressure, but also by pulling from above via negative pressure potential, where potential (a)   as water moves up the stem.

Shoot tension : The upward pull of xylem sap

2. This process occurs through (a)   .

Shoot tension : The upward pull of xylem sap
3. The (a)   inside the spongy mesophyll are quite humid, as they are constantly in contact with moist cell walls and vascular tissues filled with xylem sap

Shoot tension : The upward pull of xylem sap
4. On typical non-rainy days, the water potential of the atmosphere is far (a)   (more negative) than that of the air spaces within the mesophyll.

Shoot tension : The upward pull of xylem sap
5. As a result, water tends to move out of the stomata toward the region of (a)   water potential.

Shoot tension : The upward pull of xylem sap
6. As one moves downward through the plant, water potential (a)  

Theory of Transpiration
1. Water (a)   from the cell walls of palisade and spongy mesophyll cells into the sub-stomatal cavity

Theory of transpiration :
2. This (a)   the water potential in the cavity

Theory of transpiration :
3. Water is drawn from neighboring (a)   that have a higher water potential,

Theory of transpiration :
4. Until water is ultimately drawn from the (a)   in the leaf via the apoplastic, symplastic, or vacuolar pathway.

Cohesion :

Water molecules form a continuous column in the xylem vessels due to (a)   between them.

Adhesion :

Attractive forces between water molecules and the (a)   of the xylem help prevent the water column from collapsing downward.

Transpiration generates a negative pressure gradient that drives water upward through the plant. :

1. Endodermal cells actively secrete (a)   into the xylem.

Transpiration generates a negative pressure gradient that drives water upward through the plant :

2. This (a)   the water potential in the xylem.

Transpiration generates a negative pressure gradient that drives water upward through the plant :

3. Water from surrounding root cells is drawn into the xylem, generating (a)   .

Transpiration generates a negative pressure gradient that drives water upward through the plant :

4. Root pressure creates a positive (a)   that pushes water upward through the stem.

TRANSPIRATION :
1. Transpiration is the loss of water as water vapour from plants to the (a)   , accounting for about 99% of the water absorbed.

TRANSPIRATION :
2. Most water is lost through the stomata, while smaller amounts are lost through the (a)   and lenticels (in woody stems)

TRANSPIRATION :
3. Only about 1% of water is used in photosynthesis or other metabolic processes, and to maintain (a)  

TRANSPIRATION :
4. The rate of transpiration is regulated by the two guard cells surrounding each stoma. Guard cells open when water enters by osmosis, causing them to become turgid. Turgor pressure is generated by the active uptake of potassium ions (K⁺), a process stimulated by light. The increased solute concentration leads to water entering by (a)  

IMPORTANCE OF TRANSPIRATION :
1. Maintains the (a)   of water from roots to leaves through the xylem (transpiration pull)

IMPORTANCE OF TRANSPIRATION :
2. (a)   the plant via evaporation of water from leaf surfaces, helping regulate temperature.

IMPORTANCE OF TRANSPIRATION :
3. Facilitates the transport of (a)   from the soil to various parts of the plant

IMPORTANCE OF TRANSPIRATION :
4. Maintains (a)   , supporting plant structure and growth.

IMPORTANCE OF TRANSPIRATION :
5. Helps in the movement of (a)   by influencing the flow of phloem sap.

EXTERNAL FACTORS AFFECTING RATES OF TRANSPIRATION :
1. LIGHT INTENSITY :
Increases (a)   , enhancing transpiration

EXTERNAL FACTORS AFFECTING TRANSPIRATION RATES ;
2. TEMPERATURE
Higher temperatures increase (a)   and transpiration rate

EXTERNAL FACTORS AFFECTING TRANSPIRATION RATES :
3. HUMIDITY
Lower humidity increases the (a)   , promoting transpiration.

EXTERNAL FACTORS AFFECTING TRANSPIRATION RATES ;
4. WIND
Removes the (a)   around the leaf surface, increasing transpiration

EXTERNAL FACTORS AFFECTING TRANSPIRATION RATESN :
5. SOIL WATER AVAILABILITY
Limited water reduces (a)   and slows transpiration.

INTERNAL FACTORS AFFECTING TRANSPIRATION RATES :
1. LEAF SURFACE AREA AND STRUCTURE
Larger surface area or more (a)   increases transpiration.

INTERNAL FACTORS AFFECTING TRANSPIRATION RATES :
2. LOCATION OF STOMATA
Dicotyledonous plants have stomata on the (a)   leaf surface. Therefore reduce transpiration

INTERNAL FACTORS AFFECTING TRANSPIRATION RATES :
3. DENSITY OF STOMATA PORES
per unit of leaf and (a)   of stomatal pore.

Water Movement Through Xylem Vessels :
1. Water moves upward through the xylem vessel via (a)  

Water Movement Through Xylem Vessels :
2. The water column is under (a)   and is continuously pulled from the roots to the leaves

Water Movement Through Xylem Vessels :
3. As water evaporates from the top of the xylem, (a)   is reduced, maintaining the upward pull.

CHARACTERISTICS OF XYLEM VESSEL :
1. HOLLOW AND ELONGATED CELLS
No (a)   or organelles, forming an uninterrupted tube for efficient water flow.

CHARACTERISTICS OF XYLEM VESSEL :
2. LIGNIFIED CELL WALLS
Strengthen the vessels and prevent (a)   under negative pressure (tension).

CHARACTERISTICS OF XYLEM VESSEL :
3. NARROW DIAMETER :
Enhances (a)   and maintains water column integrity

CHARACTERISTICS OF XYLEM VESSEL :
4. PITS BETWEEN VESSELS
Allow lateral movement of water between adjacent (a)   .

CHARACTERISTICS OF XYLEM VESSEL :
5. CONTINUOUS COLUMN OF WATER
Maintained by cohesion (between (a)   ) and adhesion (to xylem walls).

Organic solutes such as sucrose, amino acids, organic acids, and ions like K⁺, Cl⁻, PO₄ ³⁻, and Mg²⁺ are transported from (a)   to the sieve tubes of the phloem. From there, they are carried to sinks .

Unlike the passive movement of xylem sap, the transport of phloem sap requires (a)   expenditure by the plant, typically in the form of active transport mechanisms.

How Solutes Move in the Phloem: Pressure Flow Model :
1. This model is based on the principles of (a)   , applied to two sugar solutions separated by a semi-permeable membrane.

How Solutes Move in the Phloem: Pressure Flow Model :
2. At the sources, carbohydrates (mainly sucrose) are (a)   into the phloem sieve tubes.

How Solutes Move in the Phloem: Pressure Flow Model :
3. This increases the (a)   in the phloem, creating a low water potential

How Solutes Move in the Phloem: Pressure Flow Model :
4. As a result, water enters the (a)   from adjacent xylem vessels by osmosis.

How Solutes Move in the Phloem: Pressure Flow Model :
5. The influx of water generates a high (a)   in the phloem at the source.

How Solutes Move in the Phloem: Pressure Flow Model :
6. This pressure pushes the (a)   (a mixture of water and solutes) along the sieve tubes toward the sink.

How Solutes Move in the Phloem: Pressure Flow Model :
7. At the sink, carbohydrates are actively (a)   from the phloem

How Solutes Move in the Phloem: Pressure Flow Model :
8. This lowers the solute concentration in the phloem, resulting in a higher (a)   .

How Solutes Move in the Phloem: Pressure Flow Model :
9. Water (a)   the phloem and returns to the xylem.

How Solutes Move in the Phloem: Pressure Flow Model :
10. This continuous cycle maintains an (a)   gradient from source to sink, driving the bulk flow of phloem sap throughout the plant.

Characteristics of phloem vessel :
1. LIVING CELLS :
Unlike xylem, phloem cells are (a)   at maturity

Characteristics of phloem vessel :
2. SIEVE TUBE ELEMENTS
Main conducting cells, aligned end to end to form (a)  

Characteristics of phloem vessel :
3. SIEVE PLATES
Perforated end walls that allow (a)   to flow between sieve elements

Characteristics of phloem vessel :
4. NO NUCLEUS IN MATURE SIEVE TUBE CELLS
Helps reduce (a)   to flow; metabolic functions are supported by companion cells.

Characteristics of phloem vessel :
5. COMPANION CELLS
Closely associated with sieve tubes; have a nucleus and control the metabolic activities of the sieve tube elements. Help load/unload sugars via (a)  

Characteristics of phloem vessel :
6. THIN CELL WALLS
Facilitate easy exchange and (a)   of solutes

Characteristics of phloem vessel :
7. TRANSPORTS BOTH DIRECTIONS
sap can move from sources to (a)  

Characteristics of phloem vessel :
8. TRANSPORTS ORGANIC SOLUTES
Mainly sucrose, amino acids, (a)   , ions, and other nutrients