(a) Define phototropism. Give one example of phototropism.(b) How does phototropism occur in a plant stem (or shoot)? Explain with the help of labelled diagrams.(c) What is meant by positive phototropism and negative phototropism? Give one example of each type.
(a) Phototropism is the growth of plant parts in response to a light stimulus. During phototropism, the cells on the plant that are farthest from the light contain a chemical called auxin reacts, which causes the plant to have elongated cells on the furthest side from the light. Hence, shows the growth and movement toward light.
An example of phototropism is the growth of plant stem in the direction of sunlight (upward).
(b) In a plant, stem (or shoot) shows positive phototropism, as it grows towards the sunlight.
(c) The movement or growth of plant parts towards the light source is known as positive phototropism, whereas the movement or growth of plant parts away from light is known as negative phototropism.
Example- Positive Phototropism - Stems (grow upwards), Negative Phototropism - Roots (grow downwards).
Related Articles
- How does phototropism occur in plants?
- The bending of the shoot of a plant in response to light is called: (a) geotropism (b) phototropism (c) thigmotropism (d) photonasty
- One of the following plant hormones is responsible for the phenomenon of phototropism in plants. This is:(a) gibberellin (b) eltroxin (c) cytokinin (d) auxin
- What is the stimulus in : (a) phototropism ? (b) geotropism ? (c) chemotropism ? (d) hydrotropism ? (e) thigmotropism ?
- (a) Define geotropism. Give one example of geotropism.(b) What is meant by 'positive geotropism' and 'negative geotropism? Give one example of each type. Draw a labelled diagram to illustrate your answer indicating the plant part which shows positive geotropism and the plant part which shows negative geotropism.(c) Name one plant part which exhibits positive thigmotropism.
- A potted plant is growing in a transparent glass jar. In this plant, X and Y are the two growing parts having a lot of meristematic tissue. It is observed that the part X of this plant exhibits positive geotropism but negative phototropism. On the other hand, part Y of this plant exhibits negative geotropism but positive phototropism.(a) Name the part X of plant.(b) Name the part Y of plant.(c) Which part of the plant, X or Y, will exhibit positive hydrotropism?(d) Which part of the plant, X or Y, can have tendrils on it ?(e) Which phytohormone causes the part X to exhibit negative phototropism?
- The growth of a pollen tube towards the ovule caused by a sugary substance as stimulus is an example of: (a) phototropism (b) chlorotropism (c) gravitropism (d) chemotropism
- Define chemotropism. Give one example of chemotropism. State whether this example is of positive chemotropism or negative chemotropism.
- The movement of a plant part in response to the force of attraction exerted by the earth is called:(a) hydrotropism (b) geotropism (c) chemotropism (d) phototropism
- The movement of sunflower in accordance with the path of the sun is due to:(a) photonasty (b) phototropism (c) hydrotropism (d) chemotropism
- Give one example each in which a force does(a) positive work(b) negative work, and(c) zero work.
- (a) Define solution.(b) Give different types of solutions with one example each.
- What is meant by (a) displacement reaction, and (b) double displacement reaction? Explain with the help of one example each.
- What is (i) phototropism and (ii) geotropism? With labelled diagrams, describe an activity to show that light and gravity change the direction that plant parts grow in.Mention the role of each of the following plant hormones: (i) Auxin and (ii) Abscisic acid
- What is meant by a primary consumer, secondary consumer, and tertiary consumer? Give one example of each.
Kickstart Your Career
Get certified by completing the course
Get Started
Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
