logging in or signing up Tropism aSGuest49254 Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINT lite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: Embed: Flash iPad Dynamic Copy Does not support media & animations Automatically changes to Flash or non-Flash embed WordPress Embed Customize Embed URL: Copy Thumbnail: Copy The presentation is successfully added In Your Favorites. Views: 3447 Category: Education License: All Rights Reserved Like it (1) Dislike it (1) Added: June 17, 2010 This Presentation is Public Favorites: 5 Presentation Description No description available. Comments Posting comment... Premium member Presentation Transcript Slide 1: THE TYPES OF MOVEMENT OBSERVED IN PLANTS BHARAT BIJUKUMAR CLASS:- X-A NEXT Slide 3: TROPISM (TROPIC MOVEMENT) NEXT A directional growth movement made by a part of a stationary plant response to unilateral stimulus. The dictionary defines tropism as an orientation of an organism to an external stimuli. There are numerous types of tropisms : Hydrotropism Phototropism Geotropism Chemotropism Thigmotropism Heliotropism Thermotropism And many more……….. (These are the 3 main types of tropism and these would broadly discussed accordingly.) Slide 4: TYPES OF TROPISM Shoot Root Hydrotropism No response Positive Geotropism Negative Positive Phototropism Positive Negative NEXT Slide 5: GEOTROPISM Geotropism is the growth of a living organism in response to gravity. There are two types of geotropisms. They are: Positive geotropism Negative geotropism Positive Geotropism It is the growth of an organism (i.e. plants) towards the centre of the earth. Negative Geotropism It is the growth of an organism away from the centre of the earth. An example of geotropism is given in the picture. NEXT Positive Geotropism Negative Geotropism Slide 6: IMPORTANCE OF GEOTROPISM Provides firm anchorage for roots. Ensure the plant can get adequate supply of water & mineral salts. NEXT Slide 7: PHOTOTROPISM The growth response of a living organism on response to light direction is called phototropism. Like geotropism even phototropism is of 2 types: 1. Positive 2. Negative In positive phototropism living organism grow towards the light. For example- Stems are positively phototrophic. In negative phototropism living organisms grow away from the light. For example- Roots are negatively phototrophic. NEXT Positive Phototropism Negative Phototropism Slide 8: IMPORTANCE OF PHOTOTROPISM Phototropism enables leaves to be in a position to receive as much sunlight as possible for photosynthesis. NEXT Slide 9: HYDROTROPISM Hydrotropism is the growth of a living organism in response to water. Hydrotropism is the directed growth of the root in relation to the gradient in moisture. It begins in the root cap with the sensing of moisture. Both positive and negative hydrotropism exist in living organisms and its direction of growth depends upon a stimulus or gradient in water concentration. NEXT Growing towards water (Positive Hydrotropism) Growing away from water (Negative Hydrotropism) Slide 10: IMPORTANCE OF HYDROTROPISM Ensures that a plant gets enough water as a raw material for photosynthesis & enough mineral salts to maintain normal growth NEXT Slide 11: Experiment Number 1 Let’s start the experiment To show Geotropism in Seedlings Slide 12: Q P R In complete darkness Plumule Radicle (a) Beginning of experiment After 2 days Q P R (b) End of experiment In complete darkness Why is it necessary to leave the apparatus in darkness ? Answer: To avoid any stimulus from light. Slide 13: Q P R In complete darkness Plumule Radicle (a) Beginning of experiment After 2 days Q P R (b) End of experiment In complete darkness Do the radicles show positive geotropism or negative geotropism? Answer: Positive geotropism. Slide 14: Q P R In complete darkness Plumule Radicle (a) Beginning of experiment After 2 days Q P R (b) End of experiment In complete darkness What advantage do the seedlings have by showing such geotropism ? Answer: Roots grow downwards deep into the soil to provide a firm anchorage underground and absorb water and mineral salts in the soil. Slide 15: EXPERIMENT NUMBER 2 Want to know what a clinostat is ? CLICK HERE To show the effect of Gravity by using a Clinostat Slide 16: Clinostat Used for controlling experiments Contains a cork disc which can be set to rotate in a vertical or horizontal plane by a motor Used to make factors uniform (evenly distributed). Let’s go back to the experiment. Slide 17: What is the purpose of marking the radicles at equal intervals ? Answer: To find out which region of the radicle grows faster. Slide 18: Does the direction of growth of the seedlings in clinostats X and Y change ? Answer: The radicle of the seedlings in clinostat X bends downwards in response to the pull of gravity since every side of the radicle of the seedling in clinostat Y is acted on by gravity, the radicle will grow straight horizontally. Slide 19: What is the purpose of setting up clinostat Y ? Ans: Serve as a control for comparison. Slide 20: To show Phototropism in Shoots EXPERIMENT NUMBER 3 Let’s start the experiment Slide 21: What has happened to the shoots of plants A, B and C ? Ans: The shoots in pot A respond by growing towards the light source. The shoot in pot B do not show any curvature but grow vertically upwards the shoots in pot C grow vertically upwards with slender and longer nodes, and carries smaller leaves which are yellow in colour. Slide 22: What is the effect of the clinostat on the shoot of plant B ? Answer: The revolving clinostat cancel out the effect of unilateral light on the shoot of plant B. Slide 23: What is the significance of phototropism to plants ? Answer: This tropism ensures that a plant gets enough light energy for photosynthesis. Slide 24: Phototropism in Shoot The shoot tip produces auxins which diffuse downward. The auxins diffuse to the shaded side due to the presence of unilateral light. High auxin concentration stimulates growth in shoot. The shaded side grows faster than the lighted side The shoot bends towards the light. Slide 25: Geotropism in Root The root tip produces auxins which diffuse to the elongation region. The auxins diffuse to the lower side due to gravity. High auxin concentration inhibits growth in root. The lower side grows slower than the upper side. The root bends downward Slide 26: SOME OTHER TYPES OF TROPISM NEXT Slide 27: THIGMOTROPISM Thigmotropism is the growth of a living organism in response to a touch/contact. As in all tropisms there exist positive and negative thigmotropism. Positive thigmotropism is where a living organism grows and clings to a wall or a fence. Negative thigmotropism is the opposite. It is where a living organism grows away from a touching object. NEXT Slide 28: HELIOTROPISM Heliotropism is quite similar to phototropism. Now, as we know that phototropism is the response of a living organism in response to light but heliotropism is the diurnal motion of the plant flowers or leaves in response to the direction of the sun. The most famous examples of heliotropism is the sunflower. Heliotropism was first described by Leonardo Da Vinci. NEXT Slide 29: THERMOTROPISM Thermotropism is the tendency of plants or other organisms to bend toward or away from heat. s the movement of a plant or plant part in response to changes in temperature. A common example is the curling of Rhododendron leaves in response to cold temperatures. Thermotropism is often called thermotropic movement . NEXT Slide 30: Chemotropism is movement caused by chemical stimulus in organisms such as bacteria and plants. An example of chemotropic movement can be seen during the growth of the pollen tube. This growth of the pollen tube is always towards the ovules. Chemotropism NEXT You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.