Why are plants different?
Many plants grow very high, but others remain small. Deciduous trees shed their leaves in autumn, but only a few conifers shed their needles. The roots of some trees grow very deep in the ground, but others remain near the surface. A few species even live in a mutually beneficial and interdependent relationship called symbiosis. Everything a plant does is for its survival so all the differences seen in plants are adaptations made depending on its environment. The plant species continues to live even after a plant dies, since it always reproduces before dying.
Why do deciduous trees shed their leaves in autumn, but conifers do not shed their needles?
Deciduous trees lose a lot of water through evaporation from their large and thin leaves. In summer, this does not pose a problem, since the roots soak in enough water from the soil, but in winter this is not possible because the soil is frozen. If the leaves are not shed before winter, the water will continue to evaporate and the plant will dry up. Moreover, the leaves can become brittle with frost and crack. Therefore, the deciduous trees shed their leaves as a precautionary measure. In contrast, the needles of the conifers are leathery and small, and there is very little evaporation through them. The needles are also frost-proof and stop their growth in winter.
How are annual rings formed in trees?
When trees grow, they accumulate wooden fibres around their heartwood. These fibres are bright and porous in spring so that a lot of water can reach the fresh leaves through them. By autumn, they become darker and thicker so the tree becomes stable and resistant to frost in the winter rest period. This process forms a bright ring and a dark ring around the heartwood every year. If you count the dark rings of a horizontal cross section of the tree trunk, you can find out the age of the tree. In the tropics, where there are no distinct seasons, the trees do not develop any rings. They grow all round the year and do not have any rest period.
In autumn, the trees store all nutrients in the stem, including those from chlorophyll. As a result, chlorophyll loses its green colour and the leaf becomes discoloured.
How do roots help plants?
Roots absorb water and the dissolved nutrient salts from the soil. They also store the nutrients as a reserve that the plant can survive on, when the soil dries up. The roots also anchor the plant firmly in y in the soil to safeguard against uprooting due to wind and bad weather. Roots change shape and adapt depending on their environment. Shallow-rooted plants, such as spruces, can hold their ground even at places where the soil cover is very thin. Plants such as pine trees, whose tap root grows deep in the ground, are found at places where water is available at great depths inside the earth.
Root peep box
You need: Two glass plates (approximately 15 x 20 cm), radish seeds, 2 rubber bands, a baking pan (as wide as the glass plates), a paper towel, water, dough
Do as follows: Put the paper towel on one of the glass plates and scatter about 15 radish seeds on it. Put the second glass plate on the paper with the seeds. Fasten both the glass plates with the rubber bands. Place this 'bundle' upright in the baking pan or make it lean against some support. Roll the dough and press it on the plate to prevent the seed pack from slipping away. Fill water in the pan and ensure that the paper towel is always in water. Turn your pack upside down every 2-3 days.
What is symbiosis?
Symbiosis is a phenomenon in which two living organisms live together in such a way that they are mutually beneficial to each other.. For example, the colourful clownfish live in a symbiotic relationship with the sea anemones. The clownfish enjoy the protection of the poisonous nettle fibres of the sea anemone and the sea anemone survives on the left-over food of the fish. The lichens that live in association with fungus and alga are also good examples of symbiotic relationships (page 61). Through the close interaction between its symbiotic partners, the lichens are able to grow in places, where they could never have existed alone. A cross-section of a flower with stigma, stamens, and ovary.
How do plants reproduce?
Plants reproduce in a variety of ways. Many species build side shoots, from which new plants grow. Plants like mosses and ferns reproduce with the help of spores, which are distributed by the wind and grow o become new plants. 'Higher plants' or the seed plants with male and female sexual organs have stamens with pollen and the stigma. The male pollen sticks Sticks to the stigma and is passed on to the egg cell in the ovary. A fertilized egg ripens to become a fruit, which contains the seeds. The seeds can be dispersed widely through Petal Anther wind or through animals Filament who eat the fruits and discard the seeds.