Transport in Plants – Class 11 Biology NEET Notes

Transport in Plants – A Smart System Without a Heart!

Have you ever wondered how a tall tree manages to send water all the way from its roots to the leaves at the top? Or how a tiny leaf manages to deliver food to every corner of a huge plant? That’s the magic of the plant transport system!

Transport in Plants – Class 11 Biology NEET Notes

Plants, unlike animals, do not have a heart or blood vessels. Yet, they transport water, minerals, and food efficiently throughout their bodies. This process is known as Transport in Plants.

Why Do Plants Need a Transport System?

Plants absorb water and minerals from the soil through their roots, and they make food in the leaves through photosynthesis. But every part of the plant—roots, stem, branches, flowers, fruits—needs both water and food to grow and survive. Hence, a transport system is essential to:

Carry water and minerals from roots to leaves
Deliver food made in leaves to other parts
Exchange gases like oxygen and carbon dioxide

What Substances Are Transported?

There are three main substances that plants transport:

1. Water – required for photosynthesis and other life processes

2. Minerals – essential for healthy growth

3. Organic nutrients (like sugars) – produced in leaves and needed by the entire plant

Types of Transport in Plants –

Plants need to move water, minerals, and food between their different parts to survive, grow, and function. This movement of substances is known as transport, and it happens through two main types – depending on the distance and direction of flow.

Unlike animals, plants do not have a heart or blood vessels. Still, they have specialized transport mechanisms to carry materials efficiently across short and long distances.

Two Main Types of Transport in Plants:

1. Short-distance Transport – movement of substances from cell to cell.

2. Long-distance Transport (Bulk Flow) – movement of substances through vascular tissues (xylem and phloem) over long distances, such as from roots to leaves.

Short comparison between short-distance transport and long-distance transport in plants:

Feature	Short-Distance Transport	Long-Distance Transport
Also Called	Local transport	Translocation
Distance Covered	Cell to cell or tissue level	From roots to leaves or vice versa
Occurs Through	Diffusion, osmosis, active transport	Xylem (water) and phloem (food)
Energy Use	May use energy (active transport)	Water – passive; Food – active
Speed	Slow	Fast
Examples	Movement of ions, sugars between cells	Water from roots to leaves, food transport

1. Short-Distance Transport (Cell to Cell) –

Short-distance transport in plants refers to the movement of substances from one cell to a neighboring cell. This type of transport is essential for distributing water, minerals, and nutrients at the microscopic level, especially within tissues and organs like leaves, roots, and stems.

It takes place over short ranges, typically within a few cells, and is the first step before long-distance transport begins through xylem or phloem.

Short-distance transport happens through three main processes:

Diffusion – passive movement of molecules from higher to lower concentration
Facilitated diffusion – diffusion with the help of carrier proteins
Active transport – movement using energy (ATP), even against the concentration gradient

2. Long-Distance Transport (Vascular Level) –

Long-distance transport in plants refers to the movement of water, minerals, and food across large distances, such as from roots to leaves or leaves to fruits and roots. This process occurs through specialized vascular tissues — xylem and phloem — that function like highways inside the plant body.

This type of transport is also called bulk flow, because it involves the mass movement of substances over long distances, usually much faster than short-distance transport.

Main Vascular Tissues Involved:

Xylem – transports water and minerals upward from roots to shoots
Phloem – transports food (mainly sugars) bidirectionally, from leaves to all other parts

Simple and clear comparison between xylem and phloem:

Feature	Xylem	Phloem
Function	Transports water and minerals	Transports food (sugars)
Direction	Only upward (from roots to leaves)	Both directions (up and down)
Type of Transport	Passive (no energy needed)	Active (uses energy)
Tissue Type	Mostly dead cells at maturity	Mostly living cells at maturity
Main Components	Tracheids, vessels, xylem parenchyma, fibers	Sieve tubes, companion cells, phloem fibers
Cell Wall	Thick and lignified	Thin and not lignified
Presence of Nucleus	No nucleus in mature xylem cells	Companion cells have nuclei
Support	Provides mechanical support	Does not provide support

Water Movement in Plants –

Water is essential for all plant activities — from photosynthesis and nutrient transport to growth and cooling. But how does water move from the soil into the roots and then travel all the way up to the top of a plant?

This process is known as water movement in plants, and it involves several coordinated steps — beginning at the roots, moving through the xylem, and finally reaching the leaves, where much of it exits via transpiration.

Why is Water Movement Important in Plants?

Maintains cell turgidity and shape
Acts as a solvent for mineral transport
Helps in photosynthesis
Controls temperature through transpiration
Enables growth and expansion of cells

Mechanisms Involved:

Osmosis – water enters root cells from the soil
Root Pressure – pushes water upward in small plants
Capillary Action – water moves up narrow xylem vessels
Transpiration Pull – main force in tall plants that pulls water upward

Water Absorption by Roots –

Water absorption by roots is the first and most crucial step in the transport of water within a plant. Roots are specially adapted to absorb water and dissolved minerals from the soil, which are then transported to the entire plant for various physiological processes.

This process mainly takes place through root hairs — tiny extensions of root epidermal cells that increase the surface area for absorption.

How Do Roots Absorb Water?

Water is absorbed from the soil into the roots primarily by:

Osmosis – movement of water from higher concentration in soil to lower concentration inside root cells
Active transport – absorption of minerals that lowers the water potential in root cells, drawing in water

Types of Water Absorption:

Passive Absorption – driven by transpiration pull; does not use energy
Active Absorption – uses root cells’ energy (ATP) to absorb water and minerals

Ascent of Sap –

The ascent of sap refers to the upward movement of water and dissolved minerals from the roots to the leaves through the xylem tissue in vascular plants. This movement is essential for supplying water needed for photosynthesis, transpiration, and nutrient transport.

Despite having no pump like a heart, plants can lift water to impressive heights — even over 100 meters in tall trees! This process is mainly passive and driven by natural physical forces.

What is 'Sap'?

Sap is the water solution of minerals and other nutrients absorbed by roots from the soil. When it moves upward through the xylem, it is specifically called xylem sap.

Root Pressure – pushes water up from below (effective in small plants)
Capillary Action – helps move water in thin xylem vessels
Transpiration Pull – the main force in tall plants; water is pulled upward due to evaporation from leaves

Transpiration –

Transpiration is the process by which plants lose water vapor from the aerial parts, mainly through tiny pores on leaves called stomata. While it may seem like just water loss, transpiration plays a vital role in pulling water upward from the roots — a phenomenon known as the transpiration pull.

This pull creates a negative pressure (suction) in the xylem, which helps in the ascent of sap — allowing water and minerals to travel to the topmost parts of even tall trees.