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How are plants adapted to growth?. Different parts of a plant are adapted to assist its growth and survival. Flowers are adapted to enable reproduction. Stems support the plant and transport nutrients. Leaves are adapted for photosynthesis, which makes materials for growth.
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How are plants adapted to growth? Different parts of a plant are adapted to assist its growth and survival. • Flowers are adapted to enable reproduction. • Stems support the plant and transport nutrients. • Leaves are adapted for photosynthesis, which makes materials for growth. • Roots anchor the plant to the ground. They also take up water and minerals from the soil.
How tall can plants grow? The tallest known plants are the Coast Redwoods, found in the USA. These grow to over 100 metres tall. That’s twice the height of Nelson’s column! The tallest native European tree is the Caucasian Fir, which can reach a height of 68 metres. Eucalyptus trees imported from Australia to Spain have been known to grow to a height of 80 metres.
How big can plants grow? The Giant Sequoia, Sequoiadendron giganteum, does not grow as tall as the Coast Redwood but it has a larger volume. The largest, General Sherman, has a volume of almost 1,500m3, about half the volume of an Olympic swimming pool.
What is the oldest plant in the world? It is common for trees to live for 100 years but rare for animals to live this long. Why? Unlike animal cells, there is no limit to the number of times plant cells can divide and multiply. Plant cells can differentiate to form specific cells throughout the plant’s life. Animal cells lose this ability early in their life cycle. Bristlecone pines, found in the USA, are the oldest-known plants. They can live for over 4,000 years.
What do plants need to grow? This plant hasn’t been looked after very well. What do plants need to grow healthily? • sunlight and an air supply • water • mineral nutrients. If a plant cannot get these from its environment, can it move to somewhere else? Plants are rooted to one place. However, they can control their direction of growth.
What controls plant growth? Plants grow in response to their environment. The shoots of these tulips grow upwards and the roots grow downwards. If a plant was unable to do this it might not be able to get enough water or sunlight from its environment. To what environmental factors do plants respond to make sure they grow properly?
What do plants respond to? Plants are very sensitive and their growth is affected by their environmental conditions. Any condition that affects plant growth is called a stimulus. What are three types of stimuli that plants respond to? light water gravity Which stimulus will have the strongest effect on the plant?
What is a tropism? A tropism is a growth movement in response to a stimulus. Plants grow towards or away from stimuli. A growth movement towards a stimulus is called a positive tropism. What is growth away from a stimulus called? Agrowth movement away from a stimulus is called a negative tropism. Will all the parts of a plant respond to a stimulus in the same way?
Are there different types of tropisms? Plant responses to stimuli are given specific names: light water gravity phototropism hydrotropism geotropism What do the names of each tropism mean? Which parts of a plant respond to these different stimuli?
How do tropisms affect growth? This plant does not have a very straight stem. What might have caused this? The plant was placed on a window sill and received light from one direction only. The shoots of plants grow towards sunlight. What is the name of this type of plant response? The response to sunlight is called phototropism.
Do plants have hormones too? Like humans, plants use hormones, (chemical messengers) to control their development. Hormones produced by plants control growth, flowering and fruit ripening. The growth of shoots and roots is controlled by a group of hormones called auxins. These chemicals are produced in the tips of the shoots and roots. What environmental stimuli might cause a plant to produce auxins?
Which way up? How do plants always grow the right way up? Plants respond to gravity to grow in the right direction.
How do roots respond to water? Roots always grow towards water, which is a positive tropism. Roots will grow sideways, or even upwards, towards water. Roots always have a stronger response to water than gravity to ensure that a plant gets the water it needs.
How do roots and shoots respond to stimuli? Plant stimuli affect certain parts of the plant in different ways. • Shoots grow towards sunlight. They are positively phototropic. • Shoots grow away from gravity. They are negatively geotropic. • Roots grow away from sunlight. They are negatively phototropic. • Roots grow towards gravity. They are positively geotropic. What experiments can be used to test these ideas?
How can plant hormones be used? Plant hormones are naturally-occurring chemicals but they can also be produced synthetically for use in gardening and agriculture such as: • growing cuttings • ripening fruit • killing weeds. Why are these purposes useful for gardeners and farmers?
How are cuttings grown? A cutting is a part of plant that is removed from the main shoot. Do cuttings have everything they need to grow? A cutting does not have roots and so has no supply of water or minerals. To stimulate root growth, cuttings are dipped into rooting powder. This contains plant growth hormones. Cuttings are genetically identical to the parent plant. This allows growers to copy successful plants.
How do plant hormones kill weeds? Weeds are unwelcome plants that compete with the plants being grown by gardeners and farmers. However, many chemicals that are potential weedkillers are toxic to animals and humans, as well as plants. Plant hormones can be used instead to make weedkillers that only affect certain plants. Most weeds have broad leaves. Cereals, which have narrow leaves, can be protected from weeds by using weedkillers that only effect the growth of broadleaved plants.
How are hormones used to ripen fruit? Fruit is often picked before it is fully ripe. Why might this help keep the fruit edible? Fruit often has to travels thousands of miles from where it is picked to where it is sold in the shops. Unripe fruit is harder and less likely to bruise than ripe fruit when transported. When the fruit reaches its destination, it can then be sprayed with artificial plant hormones to encourage ripening. Why might it be a good idea to wash fruit before eating it?
Which hormone makes fruit ripen? Ethylene is a plant hormone that controls fruit ripening. It can be sprayed on unripe fruit to speed up ripening. Some fruit, such as bananas, actually produce a large amount of ethylene, which can cause other nearby fruits to ripen. Using artificial ethylene to ripen fruit is not just a modern practice. Ancient Egyptians exposed figs to natural gas, which contains ethylene, to encourage ripening. Why might it be important to keep fruit away from coal-burning engines during transportation?
What do plants need for a balanced diet? Plants need carbon dioxide and water for photosynthesis. Do they need any other nutrients to keep healthy?
What minerals do plants need? Plants also need mineralionsfor healthy growth. Some of the most important minerals needed by plants are: nitrogen nitrates phosphorus phosphates potassium ions potassium magnesium ions magnesium How do plants obtain these minerals? The mineral ions are found in salts, dissolved in water. Plants obtain minerals when they absorb water from the soil. What type of salt are each of these elements found in?
What are minerals used for? Mineral ions are used by plants for growth and to build new cells. Plants need a variety of minerals because they are used by the plant in different ways. How are the four key mineral ions used by plants? Mineral element How mineral is used in plants nitrogen (N) making proteins for growth phosphorus (P) respiration and making roots potassium (K) respiration and photosynthesis magnesium (Mg) making chlorophyll
How do minerals affect cell formation? Minerals form the building blocks of vital cell components: • nitrogen is needed to make amino acids and proteins • phosphorus is needed to make DNA and cell membranes • potassium helps enzymes work during photosynthesis • magnesium is needed to make chlorophyll. What would happen to the plant if it was not able to get these nutrients?
What happens when plants do not get minerals? Plants do not grow properly and begin to look unhealthyif they are deprived of minerals. If a plant does not get enough of a mineral it is said to have amineral deficiency. Do all mineral deficiencies affect a plant in the same way?
Where do minerals come from? What are the sources of minerals in the soil? • Rocks.The minerals in rocks are slowly dissolved by rainwater, which is slightly acidic. These minerals are washed into the soil. • Natural fertilizers. Animal faeces and the decay of dead plants and animals return minerals to the soil. • Artificial fertilizers. These contain a ready-made mixture of the minerals needed by plants. Why might farmers need to add fertilizers to their soil?
What are NPK values? Fertilizers will often show NPK values on their labels. What do you think these letters stand for? NPK stands for nitrogen (N), phosphorus (P), and potassium (K). Fertilizers contain these elements because plants need these nutrients in higher quantities than other minerals. The numbers show the percentage of each mineral element. This fertilizer contains: • 15% nitrogen • 30% phosphorus • 15% potassium. What percentage of each mineral is in a fertilizer with the NPK value 20–10–5?
Glossary (1/2) • auxins – Plant hormones that control the rate of growth. • cutting – Part of a plant that has been removed from the main shoot and does not have roots. • ethylene – A plant hormone used to ripen fruit. • geotropism – A growth movement in response to gravity. • hydrotropism – A growth movement in response to water. • mineral deficiency –A condition that occurswhen a plant is missing one or more of the minerals needed for growth. • mineral ions–Naturally-occurring or synthetic chemicals needed for healthy plant growth.
Glossary (2/2) • mineral salts – Compounds containing essential plant minerals. • negative tropism – A growth movement away from a stimulus. • NPKvalue – The percentage of nitrogen, phosphorus and potassium available in a fertilizer. • phototropism – A growth movement in response to light. • positive tropism – A growth movement towards a stimulus. • tropism – Any growth movement in response to a stimulus.
