Abdul Rauf bin Ramli

Adrian Ong Chong Ming

Aishah Nadirah binti Noor Azman Yusof


  • responses to touch (contact)
  • use tendrils to wrap around a structure : e.g. cucumber, bitter gourd
  • twine stems around a structure : e.g. morning glory, bean plants

external image cucu_sa1.jpg

Extra Information : Vines
  • A growth form based on long, flexible stems.
  • Roots in the soil but have most of its leaves in the brighter, exposed area.
  • Certain plants always grow as vines.
  • A few grow temporarily : e.g. poison ivy and bittersweet grow as low shrubs when support is unavailable but will become vines when support is available.

external image vines.jpg
external image creeping-vines.jpg
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  • Some plants climb by twining their stems around support (e.g. morning glories, Ipomoea).
  • Others climb by clinging roots (e.g. ivy, Hedera), with twining petioles (e.g. Clematis),
  • Use tendrils (specialized shoots) e.g. Vitaceae, leaves (Bignoniaceae), or even inflorescences (Passiflora).

Aisyah binti Zainal Abidin

Alia Syakiera binti Mohd. Zuhri

Alicia Lee Su Yin (Ally)

Plants are sensitive to three types of stimuli
Example : Water, light and gravity

Tropisms : A response to stimuli from one direction

Hydrotropism - Response to water

- Roots grow towards water
- Roots show positive hydrotropism
- Positive hydroptropism ensures plants get enough water and minerals

Geotropism - Response to gravity

- Roots grow downwards in the direction of gravity
- Roots show positive geotropism
- Shoots grow upwards away from gravity
- Shoots show negative geotropism

Phototropism - Response to light

- Shoots are positively phototropic
- Roots are negatively phototropic

Thigmotropism - Response to touch

- Response by plants to contact with a solid structure
- Cucumber and bitter gourd use tendrils to wrap around a supporting structure
- Morning glory and bean plants twine their stems around other plants

Nastic Movements

- Response to stimuli in any direction
- Mimosa pudica and Venus fly trap respond quickly to touch

Andrea Chan Su Lyn

Ashleigh Yeap Jing Wen

Aw Kah Long

Chew Qq Ee

Stimuli and Responses in Plants
-Plants can also detect stimuli and respond to them.
-Shoots and Roots are very senstive to stimuli
-Stimuli = light, gravity, water, touch, temperature and chemicals
-Two types of responses : Tropism and Nastic Movement

-When the part of the plant of plant grows towards the stimulus = response is known as positive tropism
-When the part of the plant grows away from the stimulus = response is known as negative tropism
-Four common tropisms are phototropism, geotropism, hydrotropism, thigmotropism

-Growth movement shown by plants in response to LIGHT.
-Shoots grow towards light
-Roots grow away from light.

-Growth movement shown by plants in response to GRAVITY.
-Roots always grow downwards - in the direction of gravity
-Shoots grow upwards away from gravity.

-Growth movement shown by plant in response to WATER.
-Roots grow towards water.
-Shoots grow away from water.

-Response by plants to TOUCH or contact with solid structure
-Climbing plants - have weak stems and tendrils to support their own weight such as cucumber and morning glory
-Ensures that these plants can grow upwards - towards the sunlight.

Nastic Movement
-The direction of responses do not depend on the direction of the stimuli.
-Plants responses to external stimuli from any direction
-Example : Mimosa plant or Venus fly trap.

Before and After
mpudi01.jpg mpudi02.jpg

Danial Iskandar Shah

Foong Chea Yean (Melanie)

Joanna Sangeetha Vijaykumar

Kathryn Gan Xin-Yi

1.9 Stimuli and Responses in Plants

Like humans and animals, plants too can detect stimuli and respond to them.

The movements of plants are affected by external stimuli such as light, gravity, water and touch.

The movement of plant parts in response to external stimuli is called tropic movement or tropism.

The response of a plant in the direction of a stimulus is called positive tropism, while the response of the plant in the opposite direction of the stimulus is called negative tropism.

The following are the types of responses shown by plants:
Plant response - Stimulus
Phototropism - Light
Geotropism - Gravity
Hydrotropism - Water
Thigmotropism - Contact with a solid
Nastic movement - Touch

Tropism ensures that plants obtain their basic needs, such as light and water. this helps plants to survive.


Phototropism is the response of plants to light.

Plant leaves and stems grow towards light, thus exhibiting positive phototropism.

Roots always grow away from light, exhibiting negative phototropism.

Phototropism ensures that shoots and leaves obtain enough sunlight to make food though photosynthesis.


Geotropism is the response of plants to gravity.

Roots always grow towards gravity, showing positive geotropism.

Shoots grow away from gravity by growing upwards. They exhibit negative geotropism.

Positive geotropism helps the plants to obtain water and mineral salts, and the roots to hold the plants firmly in the ground. Negative geotropism helps the shoots to obtain sunlight to make food.


Hydrotropism is the response of plants to water.

Roots grow towards water, showing positive hydrotropism.

Shoots grow away from water, showing negative hydrotropism.

Positive hydrotropism helps roots to obtain water and mineral salts that are necessary for the growth and survival of plants.


Thigmotropism is the response shown by parts of plants, such as stems and tendrils, when they come into contact with a solid, and move in the direction of the stimulus.

The stems and tendrils twine around the solid in order to get support and sunlight for photosynthesis.

-Nastic Movement-

Nastic movement is the response of a part of a plant to touch, light and heat.

Sensitive plants like Mimosa exhibit nastic movement (also called seismonastic movement). When they are touched, their leaves close. The leaves will return to normal after a while.

A Venus flytrap and the pitcher plant also show this response when insects land on them.

The response of plants to light intensity is called photonastic movement. This is why flowers open during the day and close at night.

The response of plants to temperature change is called thermonastic movement. Some flowers close when there is a drop in temperature.

Law Zhi Yang

1.9 Stimuli and Responses in Plants

- They respond by growing in certain directions. Such growth responses are known as tropism.
- Sensitive to water, gravity, light, touch, temperature and chemicals.

- The growth movement of a plant in response to water.
- Roots tend to grow towards water. They show positive hydrotropism.
- Positive hydrotropism ensures the plants get enough water and minerals.

- Response to gravity.
- Detect the pull of gravity and grow in the correct direction.
- Root always grows downwards in the direction of gravity.
- This enables the root to penetrate deep into the soil to find water.

- Response to light.
- Shoots are positively phototropic, whereas roots are negatively phototropic.

- Response to touch.
- Many climbing plants are too weak to support their weights. So, they reply on other objects to keep them upright.

Nastic movements
- Response to touch.
- Two kinds of growth movements : Tropism and Nastic movements.
- Tropism are response to to stimuli which come from one direction.
- Nastic are response to stimuli which come from any direction.

Muhamad Izzwan Emir bin Muhamad Azmi

Natasha Iman binti Mohd Azri Periasamy

Philip Ooi Jun Qiang

Putri Nur Diyana binti Abdul Rashid



  • Geotropism is the growth movement shown by plants in response to gravity.
  • Plants can detect the pull the gravity and grow in the correct direction.
  • Roots will always grow downwards in the direction of gravity, showing positive geotropism.
  • Positive geotropism enables the roots to find water and support in the soil.
  • Shoots will always grow upwards away from the gravity, showing negative geotropism.
  • Negative geotropism enables the shoots to receive enough sunlight for photosynthesis.

Robin Lee Wei-Ern

1) Plants are sensitive to three mains of kinds of stimuli:
a) water
b) gravity
c) light

2)Types of growth movements:
a) Hydrotropism (Response to water)
Roots of a plant respond to water. They show positive hydrotropism.

b) Geotropism (Response to gravity)
The roots of a plant respond to gravity, thus they grow downwards. They show positive hrdrotropism.

c) Phototropism (Response to light)
The shoots of a plant grow towards light. They show positive phototropism.

d) Thigmotropism (Response to contact with a solid structure)
Climbing plants which are weak cannot support their own weight. They curl around solid structures to keep them upright.

e)Nastic movement (Response to stimuli from any direction)
Plants such as the mimosa and the Venus fly trap respond to touch. The Venus fly trap closed its leaves when an insect lands on the leaves. The insect is digested and converted into protein. The mimosa closed its leaves when touched by any object.

The Venus Fly Trap

1)The Venus Flytrap, Dionaea muscipula, is acarnivorous plant that catches and digests animal prey (mostly insects and arachnids).

2)The trapping structure is formed by the terminal portion of each of the plant's leaves.

3)The plant's common name refers to Venus, the Roman goddess of love, whereas the genus name refers to Dione.


Pitcher Plant

1)Pitcher plants are carnivorous plants whose prey-trapping mechanism features a deep cavity filled with liqiud known as a pitfall trap.

2)There are various sorts of pitfall traps evolved from rolled leaves, with selection pressure favouring more deeply cupped leaves over evolutionary time.


Roy Tang Kah Chun

Syarifah Aminah Ibrahim

Teoh Jun Vinh

Nastic Movements

In all actuality, plants really show two kinds of growth movements,

1. Tropisms
2. Nastic Movements

Tropisms only respond to stimuli from one direction. Nastic movements, however, are capable of reaction towards stimuli from any direction and do not depend on the direction of aforementioned stimuli.

Examples of plants with Nastic Movements: (click on name for link to article on Wikipedia, for extra information)
Mimosa Pudica A.K.A. Sensitive Plant
external image mimosaopen.jpgBefore response
external image mimosaclosed.jpg
After response

Dionaea muscipula
A.K.A. Venus Flytrapexternal image VFT.jpg
external image FT-Action.gifAnimation of Venus Fly Trap

Nepenthes A.K.A. Monkey Cup
external image MC.jpg
external image MCgraph.png
Graph of a Monkey Cup

The above plants respond quickly to touch stimulus.

Tropism (plur. Tropisms): A directional growth. Movements shown by plants in response to stimuli.
Stimulus (plur. Stimuli) : Changes in the surroundings.

Tio Shu Anne

-Response to water
-The roots of a plant show positive hydrotropism (roots grow toward water)
-Positive hydrotropism ensures that the plant gets enough water & minerals for healthy growth

-Response to gravity
-Roots show positive geotropism (roots grow downwards/ towards gravity)
-Shoots show negative geotropism (shoots grow upwards/ away from gravity)
-Positive geotropism enables the roots to find water and support for the plant
-Negative geotropism ensures the shoots receive enough sunlight for photosynthesis

-Response to light
-Shoots show positive phototropism and makes sure the plant receives enough sunlight for photosynthesis
-Roots show negative phototropism

-Movement in which the plant moves or grows in response to touch or contact
-Many climbing plants are too weak to support their own weight. These plants rely on other solid objects to keep them upright
-Some plants use tendrils to wrap or curl around a supporting structure (example: cucumber and bitter gourd)
-Plants such as the morning glory and the bean plant use their stems to twine around other plants or structures

Wong Qi-Shaun

Woon Tyen How

Yau Ga Luoh