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Class - : Array
One Word Answer Questions:
Q) What is the highest Mountain range on the Earth?
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Q) Which animal is found in the desert?
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Q) What are low land called that lies between mountains or hills?
    
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Q) What type of trees are grown in Costal areas?
    
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Q) The Largest part of our area is covered with what?
    
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Short Answer Questions:
Q) What is a Desert?
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Q) What is a land?
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Q) What is an Earth?
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Q) What are Mountains?
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Q) What is a Forest?
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Introduction

Plants are multicellular, mostly green organisms which are seen in our environment.

gettingknowplants

Plants Around Us


Herbs, Shrubs And Trees

Classification of plants

  1. Based on the size, nature of the stem and the life span, plants are classified into herbs, shrubs and trees. There is one more category called as creepers and climbers.
    1. A herbis a non-woody plant that has green and tender stem with few branches on.
      • It is usually short.
      • It has a very short life.
      • Herbs have a variety of uses like adding flavour to food, providing medicine for diseases and some with spiritual touch.
      • Mustard, Tulsi, Lemon grass, Mint are some of the herbs we know.

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      Mint Plant

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      Tulsi Plant


    2. A shrubis taller than a herb and has stem branching out at its base.
      • Shrub is a bushy plant.
      • The stems of a shrub are not hard but thick.
      • A common place where shrubs are grown is known as shrubbery.
      • These plants live for many years.
      • Sunflower, Rose, Lime are some of the shrubs that we see around.

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      Sunflower Plant

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      Rose Plant

    3. A treeis a woody plant that has many branches on a single stem.
      • Trees serve us lot of benefits.
      • They prevent soil erosion, maintain carbon dioxide content in the air, and provide us materials to make huts and to make furniture
      • Trees are categorised based on their height, width of their trunk, overall size, and of course their age.
      • Trees are with long life span.
      • Mango tree, Neem tree, Peepal tree are some of the trees in our surroundings.

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      Mango Tree

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      Peepal Tree


    4. Creepers are the plants with weak stems and hence cannot stand straight.
      • They grow on the ground.
      • Creepers as the name suggests creep horizontally on the ground.
      • Creepers are capable of growing new plants on their own.
      • Some creepers can also cause allergies or skin problems if touched.
      • Life time of creepers is very short.
      • Watermelon and Pumpkin are some of the examples of creepers.

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      Watermelon Plant

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      Pumpkin Plant


    5. Climbersare the plants that need support from other structures to grow and spread.
      • Climbers can either grow horizontally or vertically unlike creepers that grow only in horizontal direction. Lifespan is very short in climbers.
      • The climbing plants use these tendrils to cling on to the support firmly.
      • A tendril can be a modified leaf or a shoot or petiole like structure which is used by climbers to wrap around a support.
      • Different types of tendrils are leaf tendril, stem tendril, leaflet tendril, leaf tip tendril etc.
      • Climbers attract insects and reptiles by their bright coloured flowers and fragrance.
      • Grape plant and Money plant are some examples of climbers.

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    Grape Plant

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    Money Plant


  2. Depending on the presence of flowers, plants are classified into two types namely, flowering plants and non-flowering plants.
    1. Flowering plants are the plants which possess distinct roots, stems, flowers and fruits.Example: Mango, Papaya, Guava

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      Papaya Tree


    3. Non-flowering plants are the plants which do not have distinct roots, stem, leaves, flowers or fruits. Example: Fern, Moss.
    4. Depending on the way they obtain food, plants are classified into Autotrophs and Heterotrophs.
      1. Autotrophs are the plants which make their own food by the process of photosynthesis by using raw materials like carbon dioxide and water.Example: Most of the green plants.
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        Autotrophs

      3. Heterotrophs are the plants which depend on other organisms for their food.Example: Insectivorous plants.

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Parts Of A Plant

A typical plant has different parts in its body. Different parts of the plant are the roots, stem, leaves, flowers and fruits. The parts which are present underground are the roots. Parts which are present above the ground are stem, leaves, buds, flowers, fruits and seeds.


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Parts Of A Plant

The Root

The roots of a plant are mostly seen underground and look brown in colour. The tiny thread-like structures over the roots are the root hairs. The tip of the root is covered by root cap which is preventive in function. Root and the root hairs form the root system.

Features of root
  • Root grows towards the soil and away from the light. Hence, it is called as geotropic structure.
  • Root does not possess green colour pigment, the chlorophyll. It cannot produce food.
  • Root does not bear leaves, buds or flowers.
  • Roots along with their root hairs absorb water and minerals from the soil.
Functions of root
  • They hold the plant firmly in the soil, thereby serving as an anchor to the plant.
  • They absorb water and nutrients from the soil required for the growth of the plant.
  • Some roots also store starch and sugars in them.
  • Some roots also help in respiration. They possess special structures called as pneumatophores.
  • Some roots have useful bacteria in them to increase the soil fertility with nitrogen content.
Types of roots

Roots are of two types - tap root and fibrous roots.

  • Tap root is a primary root that grows more or less straight down into the soil, and is tapered towards the end. It is found in many of the plants. It is also called as true root. Smaller roots that branch out from the tap root are called as lateral roots. Examples of plants with tap roots are hibiscus, carrot, turnip and sunflower.
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    Tap Root

  • Fibrous roots are a group of lateral roots arising at the base of the stem. In the plants bearing fibrous roots, tap root slowly weakens and replaced by bunch of roots arising from the base of the stem. This bunches of roots form the fibrous roots. Examples of plants with fibrous roots are banana, grass and onion.

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    Fibrous Root

    Modifications of roots

    Roots in many plants are modified to perform additional functions by some modifications.


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    • Storage rootsare the roots modified to store food in them. e.g. Carrot, turnip, radish, sweet potato etc.
    • Respiratory rootsare the roots modified for respiration. The plants with mangroves roots have special structures called as pneumatophores to obtain more oxygen.
    • Parasitic rootsare the roots which arise from the stem and absorb nourishment from the host plant. e.g.Cuscuta.
    • Climbing rootsare the roots which help the plant to climb and cling on to the support. E.g. Money plant, betel.
    • Reproductive rootsare the roots which help in the process of producing the offspring.
    • Prop rootsare the roots which offer support to huge structure of the tree. e.g. Banyan tree.
    The Stem

    The stem is the part of the plant seen above the ground. It bears the leaves, flowers and fruits of a plant. It is almost green or woody. It grows towards the sunlight. It moves away from the ground.

    Features of stem
    • They support the entire plant to stand as a whole.
    • They are always phototrophic. i.e. they grow towards light.
    • Stem has nodes separated by internodes. Stem bears branches, leaves, flowers and fruits.

    • Functions of stem
    • Stem helps in transportation of absorbed water and nutrients through vascular tissue from roots to leaves
    • Stem also transports food from the leaves to different storage organs.
    • Stem exposes leaves to light and help them in performing the process of photosynthesis.
    • The stem bearing leaves helps in the process of transpiration. Transpiration is the process by which plants release excess water in the form of water vapour through minute openings in the leaves called as stomata.
    • Sometimes stem can store food which is mostly underground.
    • Stem can store water by becoming fleshy as in desert plants.
    • Stem can perform photosynthesis when leaves are reduced or absent as in desert plants.

    Modifications of stem

    Stems in many plants are modified to perform additional functions by some modifications.

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    Modified Stem Of A Plant

    • Storage of foodIn some plants, underground stem is modified to store food in the form of starch. Three types of underground modifications of stem are tubers (e.g. Potato), rhizome (e.g. Ginger) and bulb (e.g. Onion).
    • PhotosynthesisIn some desert plants, leaves are absent or reduced to spines. Here, the stem performs photosynthesis to synthesise food.
    • Protective structuresIn some plants like rose, stems are modified into thorns to protect the plant from being eaten by animals.
    • Supportive structuresIn climbing plants, stems are modified sometimes into structures which twine around the support.
    • Storage of waterIn some plants like cactus and jade, stems become fleshy and succulent to store water.
    The Leaves

    Leaves are the structures which develop on branches. These are green coloured structures rich in chloroplasts. As they have chlorophyll in them, they are considered to be food factories of the plant. Photosynthesis occurs in the leaves. Each leaf bears a bud in its axil.

    Parts of leaf
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    Parts Of A Leaf


    • The point of attachment of the leaf to the node on the stem is called as leaf base.
    • Leaf bears a stalk with which it is attached to the stem. It is called as petiole.
    • The flat part of the leaf exposed to light is called as lamina.
    • A thin structure which extends from the leaf base to the tip on the lamina is called as mid-vein. Many small thread like structures extend from the mid rib to the leaf margin. These are called as veinlets. Arrangement of veins on the lamina of the leaf is called as venation. Veins help in transportation of food and water.
    • Two types of arrangement of veins on the leaf are parallel venation and reticulate venation.
    Types of leaves

    Leaves can be simple leaf or compound leaves.

    • Simple leaf is a single leaf with undivided lamina. The veins are parallel along the length of the leaf. This is called parallel venation.
    • Compound leaf is a leaf which has divided lamina into a number of leaflets. The central structure called rachis bears all the leaflets. The veins form a net like design, on both sides of the leaf. This is called reticulate venation.
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    Arrangement of leaves

    Leaves are arranged in different patterns at the node on the stem. Arrangement can be alternate, opposite, whorl etc.

    • Alternate leaves are the ones which arise one at a node.
    • Opposite leaves are the leaves which arise as two at a node.
    • Whorl type of arrangement includes three or more leaves arise at a node.
    Structure and surface of the leaf
    • Leaf has two surfaces namely, dorsal surface and ventral surface. Dorsal surface is the upper surface which is exposed to sunlight. It has number of chloroplasts having lot of chlorophyll in them. Upper surface of the leaf is dark green in colour.
    • Leaf has many pores called as stomata on both of its sides. These stomata help in exchange of gases like oxygen and carbon dioxide. Stomata also help in loss of excess water by the process of transpiration.

    • Functions of leaf
    • Leaves are the food factories of the plant which help in the process of photosynthesis to synthesise their food. They make use of raw materials like carbon dioxide and water in the presence of chlorophyll and sunlight.
    • Leaves lose excess water by the process of transpiration. Transpiration cools the body of the plant by regulating the temperature.

    • Modifications of leaf
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      Modification Of Leaf

    • In weak stemmed plants, leaves are modified into special structures which twine around a support. These are tendrils. These offer support to the plant while climbing up.
    • In some plants like onion, leaves are modified to store food. These are termed to be scaly leaves.
    • In some desert plants like cactus, leaves are reduced to spines so as to reduce loss of water through transpiration. These spines are also called as thorns. Thorns protect these plants from grazing animals
    • In some insectivorous plants, leaves are modified into pitchers where they are used to trap insects. These insects can be digested inside the body of the plant. In this way, plants obtain nitrogen from animals.
    Flower

    Flower is a reproductive structure of the plant. The different parts of a flower include sepals, petals, stamens and pistil. Flower helps the plant to give rise to new plants by the process of sexual reproduction.


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    Structure Of A Flower


    Parts Of A Flower
    Sepals
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    Sepal


    These are hard, leaf-like structures around the base of a flower.

    • They protect the bud before it blooms into a flower.
    • These are green in colour in most of the plants.
    • The sepals are collectively called as calyx.
    • The number of sepals varies from plant to plant.
    Petals
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    Petals

    These are brightly coloured portions of a flower.

    • They petals are collectively called as corolla.
    • They are brightly coloured so as to attract insects and birds for pollination.
    • The number of petals is almost equal to the number of sepals in a flower.
    • In some flowers, the petals and sepals combine to form a round structure called as Tepal.
    Stamens
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    Stamens

    The stamens are the male reproductive parts of a flower. Stamen is made up of a filament and anther.

    • Anther is a bilobed (consisting of two lobes) structure at the tip of the filament.
    • Anther contains male reproductive cells, the pollen grains.
    • Pollen grains are the male reproductive cells which are very light, that they can be carried away by wind.
    • Pollen grain has a thick covering made up of two layers, outer exine and inner intine.
    Pistil
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    Pistil

    The pistil is the female reproductive part of a flower. It is made up of the stigma, the style and the ovary.

    • Stigma is a bulged sticky structure at the tip of the pistil. As it is sticky it receives pollen grains from the male reproductive structure.
    • Style is a long tube like structure which allows pollen grain to travel from stigma to ovule, the egg cell.
    • Ovary is a large lobed structure at the base of the carpel. It contains the female reproductive cells, the ovules. The number and arrangement of ovules differ in different flowering plants.
    Fruit

    Fertilisation is the union of male and female cells in a flower to produce a fruit. Fruit is basically the fertilised ovary. This grows in size to store sugars. Ovules develop into seeds. So, fruits enclose seeds.

    gettingknowplants

    Enclose Seeds In Fruits

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