The bending of shoot towards light is an example of

Phototropism: • Phototropism is one kind of tropic movement in which plants bend or grow in response to light stimuli. • Stems show positive phototropism (stems grow or bend toward the light) and roots show negative phototropism (roots grow in the direction opposite to the light). Final answer: Bending of shoot toward the light is phototropism.

Greg Foot explains how plants respond to light and gravity, and the role of auxins in controlling and coordinating plant growth Just like animals, plants produce hormones. These chemical molecules act as messages from one part of the plant to another. Important plant hormones include: • auxins which control the rate of cell elongation • gibberellins also control cell elongation but also influence germination, flowering and dropping fruit and leaves • ethene , also known as ethylene, which controls fruit ripening Auxins Auxins are a family of hormones found in plants. Auxins are mostly made in the tips of the shoots and roots, and can diffuse to other parts of the shoots or roots. They change the rate of elongation in plant cells, controlling how long they become. Shoots and roots respond differently to high concentrations of auxins: • cells in shoots grow more • cells in roots grow less Phototropism Phototropism is how plant shoots grow towards the light. In a shoot, the shaded side contains more auxin. This means that the shaded side grows longer, causing the shoot to bend towards the light. Many famous scientists including Charles Darwin (1809-1882) completed experiments like this on phototropism. Seedlings Results and explanation A The tips have been removed. No auxin is produced and the shoots do not grow longer. B The tips have been covered so light cannot reach them. Auxin is in the same concentration on both sides of the shoots, so they grow evenly and longer on bot...

• Geotropism is the response of the plant parts in the direction of gravitational force. • Hydrotropism is the response of roots towards the water concentration. • Chemotropism is the response of plant parts in the direction of the chemical stimulus. • Phototropism is the response of plant parts in the direction of light.

When growing plant shoot tip detects light a hormone called auxin is synthesised in the shoot tip which is sensitive to light. Auxin diffuses towards the shady side of the stem. It stimulates the growth of cells on the shady side of the plant which causes bending of the plant to the other side. This gives the appearance that the stem of the plant bends in the direction of light. Categories • • (31.9k) • (8.8k) • (764k) • (261k) • (257k) • (218k) • (248k) • (2.9k) • (5.2k) • (664) • (121k) • (72.1k) • (3.8k) • (19.6k) • (1.4k) • (14.2k) • (12.5k) • (9.3k) • (7.7k) • (3.9k) • (6.7k) • (63.8k) • (26.6k) • (23.7k) • (14.6k) • (25.7k) • (530) • (84) • (766) • (49.1k) • (63.8k) • (1.8k) • (59.3k) • (24.5k)

You might have heard people talk about Einstein’s speed of light, and that it’s always the same. The part that most people leave out is that this is only true in a vacuum—when there’s no pesky molecules of air or water to slow it down. But when light moves through a more familiar medium like air, it moves more slowly due to the interactions of individual photons with the molecules in the material. In general, the more optically dense the medium, the slower the light will move. So what happens to the light when it goes from one medium to another? Imagine that you and your friends are at the beach. You all decide to swim together, so you link arms and approach the water as a straight line. As you start walking into the water, you all slow down, because it’s harder to walk through water than through air. So imagine that you approach the water at an angle relative to the shoreline. The person on the end will meet the water and slow down first, then the next person in line, then the next, until everyone is walking through the water. Because one end of the line slowed down before the other end, the line of people becomes crooked, with the people who are still on the beach at a different angle relative to the water’s edge than the people who have already entered the ocean. For example, imagine you are looking out the window. You have air, glass, and then air again. Glass is denser than air, so the light from outside passes from a fast medium, through a slow medium and into a fast...

Greg Foot explains how plants respond to light and gravity, and the role of auxins in controlling and coordinating plant growth In order to survive, plants require light and water for photosynthesis . They have developed responses called tropisms to help ensure they grow towards adequate sources of light and water. There are two main types of tropisms: • positive tropisms - the plant grows towards the stimulus • negative tropisms - the plant grows away from the stimulus Phototropism is the growth of plant shoots towards the light. Responses to stimuli of different parts of the plant • In the plant stem, responses to light are known as a positive phototropism, which means the stem grows towards the light. • In the plant root, responses to light are known as a negative phototropism, which means the root grows away from the light. Positive phototropism in plant stems Auxins Auxins are a family of plant hormones. An example of a specific auxin is IAA, which is known as Indole acetic acid. They are mostly made in the tips of the growing stems and roots, which are known as apical meristems, and can diffuse to other parts of the stems or roots. Unequal distribution of auxin can cause unequal growth rates in plants and shoots. Auxins change the rates of elongation in plant cells and control growth of stems and roots. Stems and roots respond differently to high concentrations of auxins: • cells in stems grow more • cells in roots grow less Phototropisms In a stem, the shaded side c...

The bending of the stem of a plant towards light is called as phototropism. Auxins also play a part in phototropism, an occurrence that involves plants bending or moving away from light. The shoot tip is responsible for directional movement by the plant in response to sunlight, as this is the area where auxins can be found. Sunlight eradicates auxin, meaning that the part of the shoot tip of the plant which is receiving direct sunlight will have the least amount of auxin. The extra auxin present on the shaded side promotes more cell division and elongation, causing the plant to bend towards the sunlight after this lop-sided growth.

• Geotropism is the response of the plant parts in the direction of gravitational force. • Hydrotropism is the response of roots towards the water concentration. • Chemotropism is the response of plant parts in the direction of the chemical stimulus. • Phototropism is the response of plant parts in the direction of light.

The bending of the stem of a plant towards light is called as phototropism. Auxins also play a part in phototropism, an occurrence that involves plants bending or moving away from light. The shoot tip is responsible for directional movement by the plant in response to sunlight, as this is the area where auxins can be found. Sunlight eradicates auxin, meaning that the part of the shoot tip of the plant which is receiving direct sunlight will have the least amount of auxin. The extra auxin present on the shaded side promotes more cell division and elongation, causing the plant to bend towards the sunlight after this lop-sided growth.

Greg Foot explains how plants respond to light and gravity, and the role of auxins in controlling and coordinating plant growth Just like animals, plants produce hormones. These chemical molecules act as messages from one part of the plant to another. Important plant hormones include: • auxins which control the rate of cell elongation • gibberellins also control cell elongation but also influence germination, flowering and dropping fruit and leaves • ethene , also known as ethylene, which controls fruit ripening Auxins Auxins are a family of hormones found in plants. Auxins are mostly made in the tips of the shoots and roots, and can diffuse to other parts of the shoots or roots. They change the rate of elongation in plant cells, controlling how long they become. Shoots and roots respond differently to high concentrations of auxins: • cells in shoots grow more • cells in roots grow less Phototropism Phototropism is how plant shoots grow towards the light. In a shoot, the shaded side contains more auxin. This means that the shaded side grows longer, causing the shoot to bend towards the light. Many famous scientists including Charles Darwin (1809-1882) completed experiments like this on phototropism. Seedlings Results and explanation A The tips have been removed. No auxin is produced and the shoots do not grow longer. B The tips have been covered so light cannot reach them. Auxin is in the same concentration on both sides of the shoots, so they grow evenly and longer on bot...