BiologyICSE Class 10 · Transpiration

Transpiration: Types, Significance, Guttation and Bleeding (ICSE Class 10 Biology)

Updated 15 October 2026 · Fact-checked

Transpiration is the loss of water as water vapour from the aerial parts of a plant, mostly through stomata. It creates the transpiration pull that lifts water and minerals, cools the leaves and keeps water moving through the plant. Guttation, by contrast, is the loss of liquid water drops through hydathodes at leaf tips and margins.

Understand Transpiration: Types, Significance and Guttation

What transpiration is. Of all the water a plant absorbs, only a small part is used in photosynthesis and growth; most of it evaporates from the leaves. Transpiration is the loss of water in the form of vapour from the aerial parts of the plant. Inside the leaf, water evaporates from the moist walls of mesophyll cells into the air spaces, and the vapour diffuses out through open stomata into the drier air.

Three types.

Type	Through	Share of water lost
Stomatal	stomata, mostly on leaves	by far the largest
Cuticular	the waxy cuticle of leaves and young stems	small; more where the cuticle is thin
Lenticular	lenticels in the bark of woody stems and fruits	very small

Significance (advantages) of transpiration. These are the expected points for the 2024 two-mark question.
1. Transpiration pull: water lost from leaves is replaced from the xylem, creating a suction that is the main force for the ascent of sap.
2. Distribution of minerals: dissolved minerals are carried up with the rising water to the leaves and growing parts.
3. Cooling: evaporation absorbs heat (latent heat), keeping leaves cooler in strong sunlight, much as sweat cools us.
4. Rainfall: the vapour released by forests adds to atmospheric moisture and helps bring rain.

A necessary evil. Transpiration is called a necessary evil: it is unavoidable, because the same open stomata that let CO₂ in for photosynthesis also let water vapour out, and it is useful; but when loss exceeds absorption on hot, dry days the plant wilts, and prolonged loss can kill it.

Adaptations to reduce transpiration (plants of dry places).

Thick waxy cuticle on leaves.
Sunken stomata, in pits, often guarded by hairs (as in oleander).
Fewer stomata, mostly on the lower surface.
Hairs on leaves that trap a layer of moist air.
Leaves reduced to spines, with a green, fleshy stem doing photosynthesis (cactus).
Rolling or folding of leaves in dry weather (some grasses).
Shedding leaves in the dry season (deciduous trees).

Guttation (a brief idea). The loss of water in the form of liquid droplets from the margins or tips of leaves, through special pores called hydathodes found at the ends of veins. It happens on cool, humid nights and early mornings, when root pressure is high but transpiration is low, so excess water is pushed out. Examples: grasses, tomato, strawberry, garden nasturtium. Guttation water contains dissolved salts and leaves a crust when it dries.

Bleeding (a brief idea). The oozing of sap from a cut or injured part of a plant, caused by root pressure. Examples: sap dripping from a stem cut near the base; tapping of palms for sap and of rubber trees for latex.

Transpiration versus guttation.

Point	Transpiration	Guttation
Form of water	vapour	liquid drops
Through	stomata, cuticle, lenticels	hydathodes
Time	mostly by day	night and early morning
Water	pure	contains dissolved salts
Control	stomata open and close	not regulated

Flow chart. Soil water → root hair → xylem of root and stem → leaf veins → mesophyll cell walls → evaporation into air spaces → diffusion out through stomata → air; the loss at the top pulls the water column up behind it.

Draw-and-label checklist: hydathode or guttation leaf. Leaf outline with vein endings reaching the margin; droplets at the tips of the teeth; label: leaf margin, vein ending, hydathode, water droplet. For a tree diagram: label roots (absorption), stem (ascent of sap), leaves (transpiration).

Transpiration: Types, Significance and Guttation: key facts

Types of transpiration: Stomatal through stomata, largest share
Cuticular through cuticle, small
Lenticular through lenticels in bark, very small; Know one feature of each.
Advantages of transpiration: Creates transpiration pull
Carries minerals upward
Cools the leaves
Adds water vapour that helps bring rain; Any two make a 2-mark answer.
Transpiration, guttation, bleeding: Transpiration vapour, stomata, day
Guttation liquid drops, hydathodes at leaf tips and margins, night or early morning
Bleeding sap oozing from a cut or wound, due to root pressure; Guttation and bleeding are both driven by root pressure.

Stomatal	through stomata, largest share
Cuticular	through cuticle, small
Lenticular	through lenticels in bark, very small

Transpiration	vapour, stomata, day
Guttation	liquid drops, hydathodes at leaf tips and margins, night or early morning
Bleeding	sap oozing from a cut or wound, due to root pressure

How to answer Transpiration: Types, Significance and Guttation questions

ICSE asks you to define transpiration, list its advantages, name its types, identify guttation from a description, locate hydathodes, and explain adaptations to reduce water loss.

1Define with three keywords: water vapour, aerial parts, mainly through stomata.
2For advantages, pick from the four standard points; do not write 'removes excess water'.
3For guttation, mention liquid drops, hydathodes at the ends of veins at leaf margins or tips, and high root pressure with low transpiration.
4For adaptations, link each feature to how it cuts water loss.
5For tree diagrams, name the process at roots, stem and leaves in that order.

Transpiration: Types, Significance and Guttation in real life

The idea, met in an everyday situation. Answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Shade of a tree is cooler

Suppose on a May afternoon you stand first under a large neem tree and then under a tin shed of the same size. The air under the tree feels noticeably cooler.

Explain why, using transpiration.

Try it first, then show the solutionSolution

Both block direct sunlight, so shade alone does not explain the difference.
The tree's leaves release large amounts of water vapour by transpiration.
Evaporation absorbs heat from the leaves and the surrounding air, cooling them.
The tin shed has no evaporating surface and heats up, radiating warmth.

Answer: Transpiration from the leaves absorbs heat by evaporation, cooling the tree and the air beneath it.

Memory hook: Trees sweat to stay cool.

Dew-like drops on grass

Suppose a student on a winter morning sees neat drops at the very tips of grass blades on a lawn, even under a roof where dew cannot form.

What are these drops, and why do they appear only at the tips?

Try it first, then show the solutionSolution

On a cool, humid night transpiration is low, but roots keep absorbing water, so root pressure builds up.
Excess water is pushed out as liquid through hydathodes at the ends of the veins.
In grass the vein endings lie at the blade tips, so drops form there.
This is guttation, not dew, which would cover the whole surface.

Answer: Guttation drops from hydathodes at the vein endings at the blade tips, due to high root pressure and low transpiration.

Memory hook: Gutter-tion: drops drip from the edges like a gutter.

Tricks to remember Transpiration: Types, Significance and Guttation

Short memory aids. Say each one aloud once, then use it on a question the same day.

Stomatal, Cuticular, Lenticular = Big, Small, Tiny
S-C-L in falling order of water loss.
Use it when: Ranking the three types.
PMCR for advantages
Pull, Minerals, Cooling, Rain.
Use it when: Writing two or more advantages quickly.
Hydathodes at the edges
Hydro + 'path' at the leaf's edge: the water path ends at the margin.
Use it when: Locating hydathodes correctly.

Transpiration: Types, Significance and Guttation: solved examples

Ordered from board level to HOTS. Try each one before you open the solution.

Example 1: Two advantages · 2 marks · Short answerBoard level

A farmer says that transpiration only wastes the water he pumps into his field. Give two ways in which transpiration is useful to the plant or its surroundings. (The 2024 paper asked for advantages of transpiration.)

Try it first, then show the solutionSolution

It creates a suction force (transpiration pull) that helps the ascent of sap (1 mark).
It cools the leaf surface by evaporation; or it helps distribute water and mineral salts (1 mark).

Answer: Transpiration pull for ascent of sap; cooling of leaves (or mineral distribution, or rainfall).

Example 2: Strawberry leaf margins · 1 mark · MCQBoard level

Early on a cool, humid morning, tiny drops of liquid water are seen along the toothed edges of tomato leaves. This loss of water is called:
(a) transpiration (b) guttation (c) bleeding (d) osmosis
(The 2024 paper tested this idea with strawberry leaves.)

Try it first, then show the solutionSolution

Liquid drops from leaf margins come out through hydathodes: guttation.

Answer: (b) guttation.

Example 3: Transpiration versus guttation · 3 marks · Short answerHarder board level

Give three differences between transpiration and guttation.

Try it first, then show the solutionSolution

Transpiration: water lost as vapour; guttation: as liquid drops (1 mark).
Transpiration: through stomata, cuticle and lenticels; guttation: through hydathodes at leaf tips and margins (1 mark).
Transpiration: mostly by day and controlled by stomata; guttation: at night or early morning, not regulated (1 mark).

Answer: Vapour versus liquid; stomata versus hydathodes; day and regulated versus night and unregulated.

Example 4: Necessary evil · 2 marks · Short answerHarder board level

Why is transpiration called a 'necessary evil'?

Try it first, then show the solutionSolution

Necessary: it creates transpiration pull, distributes minerals and cools the leaves; it is unavoidable because stomata must open for CO₂ (1 mark).
Evil: excessive loss on hot dry days exceeds absorption, causing wilting and sometimes death (1 mark).

Answer: Useful and unavoidable, but excessive loss causes wilting.

Example 5: Weight loss of a potted plant · 3 marks · Case-basedHOTS / competency

Suppose a well-watered potted plant, with its pot and soil sealed in a polythene bag, weighs 850 g at 10 a.m. and 826 g at 4 p.m. (a) Why is the soil covered? (b) Calculate the average rate of water loss per hour. (c) Why would the loss be less if the plant were kept indoors on a humid day?

Try it first, then show the solutionSolution

(a) To prevent evaporation from the soil, so all weight lost is due to transpiration from the shoot (1 mark).
(b) Loss = 850 − 826 = 24 g in 6 hours = 4 g per hour (1 mark).
(c) Indoors there is less light (stomata partly closed) and humid air reduces the diffusion gradient, so transpiration slows (1 mark).

Answer: (a) To stop soil evaporation. (b) 4 g per hour. (c) Less light and higher humidity lower transpiration.

Example 6: Desert plant design · 3 marks · Short answerHOTS / competency

Suppose a student is asked to design a plant for a hot desert. Suggest three features of its leaves or stem and explain how each reduces transpiration.

Try it first, then show the solutionSolution

Leaves reduced to spines, with a green stem for photosynthesis: less surface for water loss (1 mark).
Thick waxy cuticle: almost no cuticular transpiration (1 mark).
Few, sunken stomata surrounded by hairs: moist air trapped near the pore lowers the diffusion of vapour (1 mark).

Answer: Spines, thick cuticle, sunken stomata with hairs (or rolled leaves, leaf fall).

Where students lose marks in Transpiration: Types, Significance and Guttation

The slips examiners see most often, and what to write instead.

Mistake: Irrelevant 'advantage' of transpiration
CISCE examiners' comments (2024): candidates wrote irrelevant points such as 'transpiration removes excess water from plants' instead of the expected cooling, suction force, distribution of water and minerals, or bringing rain.
Do this: Use the four standard points only.
Usually costs: 1-2 marks.
Mistake: Guttation answered as osmosis
CISCE examiners' comments (2024): for water lost from the margins of strawberry leaves, candidates wrote osmosis instead of guttation.
Do this: Liquid drops at leaf margins always mean guttation.
Usually costs: 1 mark.
Mistake: Locating hydathodes only as 'leaves'
CISCE examiners' comments (2025): candidates wrote only 'leaves' instead of the ends of veins at the margins or tips of leaves, and confused hydathodes with stomata.
Do this: Write 'at the ends of veins at the tips or margins of leaves'.
Usually costs: 1 mark.
Mistake: Missing the three phenomena in a tree picture
CISCE examiners' comments (2025): candidates failed to identify absorption (roots), ascent of sap (stem) and transpiration (leaves).
Do this: Roots absorb, stem conducts, leaves transpire.
Usually costs: 1-3 marks.

Exam tips

Use 'water vapour' in every definition of transpiration.
Advantages: pull, minerals, cooling, rain.
Hydathode location needs 'tips or margins' and 'ends of veins'.
For adaptations, write the feature and how it reduces water loss.

Practice questions on Transpiration: Types, Significance and Guttation

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

Q1 · 1 mark · MCQBoard level
Hydathodes are located:
(a) on the lower surface of leaves (b) at the ends of veins at leaf tips and margins (c) in the bark (d) in the root hair zone
Hint
Where guttation drops appear.
Answer
(b).
Q2 · 1 mark · Very short answerBoard level
Name the openings in the bark of woody stems through which a little transpiration occurs.
Hint
Lenticular transpiration.
Answer
Lenticels.
Q3 · 2 marks · Short answerHarder board level
What is bleeding in plants? Give one example.
Hint
Cut or injured part.
Answer
The oozing of sap from a cut or injured part of a plant due to root pressure, e.g. sap from a stem cut near the base, or tapping palms for sap.
Q4 · 2 marks · Short answerHarder board level
State the conditions under which guttation occurs.
Hint
Root pressure versus transpiration.
Answer
On cool, humid nights or early mornings, when the soil is moist, absorption and root pressure are high and transpiration is low.
Q5 · 1 mark · Assertion-reasonHarder board level
Assertion (A): Oleander leaves lose less water than mango leaves of the same size.
Reason (R): Oleander has sunken stomata in pits lined with hairs.
(a) (A) is true and (R) is false.
(b) (A) is false and (R) is true.
(c) Both (A) and (R) are true, and (R) is the correct explanation of (A).
(d) Both (A) and (R) are true, but (R) is not the correct explanation of (A).
Hint
Adaptation to dry places.
Answer
(c).
Q6 · 2 marks · Short answerHarder board level
Explain how transpiration helps in the ascent of sap.
Hint
Suction at the top.
Answer
Water evaporating from leaf cells is replaced from the xylem in the leaf; this creates a suction (transpiration pull) that, with cohesion of water molecules, pulls the unbroken water column up the xylem from the roots.
Q7 · 2 marks · Short answerHarder board level
Why do transplanted seedlings often have some of their leaves removed?
Hint
Damaged roots.
Answer
Transplanting damages root hairs, so absorption falls. Removing leaves reduces the transpiring surface, so water loss does not exceed absorption and the seedling does not wilt.
Q8 · 3 marks · Case-basedHOTS / competency
Read and answer.
Suppose a leafy shoot in a test tube of water, with a thin layer of oil on the water, weighs 64.0 g at 9 a.m. and 61.6 g at 1 p.m.
(a) Why is the oil layer added? (1)
(b) Calculate the mass lost per hour. (1)
(c) What percentage of the starting mass was lost? (1)
Hint
4 hours.
Answer
(a) To prevent evaporation from the water surface. (b) 2.4 g ÷ 4 h = 0.6 g per hour. (c) 2.4 ÷ 64.0 × 100 = 3.75%.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1.Through which structure does most transpiration occur?Show answer
Stomata.
2.In what form is water lost in guttation?Show answer
Liquid droplets.
3.What causes guttation and bleeding?Show answer
Root pressure.
4.Name one plant that shows guttation.Show answer
Grass, tomato, strawberry or garden nasturtium.
5.Name one adaptation of a cactus to reduce transpiration.Show answer
Leaves reduced to spines (or thick cuticle, sunken stomata).

Transpiration: Types, Significance and Guttation: frequently asked questions

Is transpiration the same as evaporation?

It is evaporation from a living plant, controlled partly by the opening and closing of stomata, so it is a biological process, not just a physical one.

Why can a plant not simply stop transpiring?

Stomata must open to take in carbon dioxide for photosynthesis, and water vapour escapes through the same pores.

Do I need the details of hydathode structure?

No. The syllabus asks for a brief idea of guttation and bleeding: what they are, where, when and why.

Is guttation harmful?

Usually not, but salts left behind when the drops dry can injure the leaf margins.