Morphology of Flowering Plants: Structure of Leaf I Free Notes I LetsBloomStudyMaterial I Plant Anatomy #biology #pgtbiology #kvs #nvs #emrs

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STRUCTURE OF LEAF

  • The leaf is a lateral, generally flattened structure borne on the stem.

  • It develops at the node and bears a bud in its axil called as Axillary bud.
  • The axillary bud later develops into a branch.
  • Leaves originate from shoot apical meristems and are arranged in an acropetal order.
  • They are the most important vegetative organs for photosynthesis, Transpiration, Respiration etc.
  • Phytomer is the part of shoot axis consisting of node. leaf, axillary bud and internode.

  • A typical leaf consists of three main parts: leaf base, petiole and lamina

  • 1. Leaf Base:
  • The leaf is attached to the stem by the leaf base and may bear two lateral small leaf like structures called stipules.
  • Stipules are two lateral short outgrowth that protects young leaves and Axillary bud.
  • In monocotyledons, the leaf base expands into a sheath covering the stem partially or wholly called as Sheathing Leaf Base.
  • In some leguminous plants the leaf base may become swollen, which is called the Pulvinus.
  • 2. Petiole:
  • Petiole is cylindrical, long and thin. The petiole help hold the blade to light. It allows leaf blades to flutter in wind, thereby cooling the leaf and bringing fresh air to leaf surface.
  • 3.Leaf Lamina/ Leaf Blade:
  • It is the expanded part of the leaf that carry out photosynthesis
  • Lamina comprises of veins and veinlets. There is, usually, a middle prominent vein, which is known as the midrib or Principal Vein.
  • Veins provide rigidity to the leaf blade and act as channels of transport for water, minerals and food materials.

QUESTION PRACTICE:

1.which of the following features distinguish monocot plant from dicot

  • Phyllotaxy
  • Venation
  • Aestivation
  • vernation

2.When the incision of lamina reach up to the midrib breaking it into numbers of leaflets, the leaf is called as compound

Phyllotaxy is the pattern of arrangement of leaves on the stem or branch

Which of the above is incorrect (DSSSB)

  • Only 1
  • Only 2
  • Both1 and 2
  • Nether 1 nor 2

3.Observe VS of dicot leaf given below and correctly identify the part labelled as A, B, C



A- Bundle Sheat B- Palisade C-Spongy
A-Bulliform cell B-Guard cell C-Stroma
A-Bundle sheath B-Bulliform cell C-Stroma
A-Bulliform cell B-Bundle sheath C-Stroma

4.Circinate venation is characteristics of leaves of (NVS 2022)

  • Conifers 
  • Thuja
  • Cycads
  • Gnetum

5.The term Phytomer is used to denote: NVS 2022

  • the period between appearance of two successive leaf primordia
  • the part of shoot axis consisting of node. leaf, axillary bud and internode
  • the transformation of shoot apex into flowering bud
  • the cells which stop dividing


6.The term Plastochrome refers to (NVS 2022)

  • Active meristematic tissue
  • Differentiation of axillary buds
  • the period between appearance of two successive leaf primordia
  • Expansion of leaf primordium into a mature leaf lamina


7.If the leaflets are attached at tip of petiole that leaf is called (KVS 2017)

  • Pinnate compound leaf
  • Palmate compound leaf
  • Simple leaf
  • Compound leaf
8. Frond is a (KVS PGT Biology)
  • Leaf 
  • Bud
  • Petiole
  • Thorn
Match the modified organs in group I with their corresponding prototypic forms in group II and choose the correct options 
  • P1 Q2 R2 S1
  • P2 Q1 R1 S2
  • P1 Q2 R1 S2
  • P1 Q1 R2 S1

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