Botany lecture notes

Difference between Microspores and Megaspores: Comparison Table


microspores vs megaspores

Microspores vs Megaspores
(Similarities and Differences between Microspores and Megaspores)

Microspores and megaspores are sexual spores produced by vascular plants (some Pteridophytes and all Gymnosperms and Angiosperms) for sexual reproduction. Both microspores and megaspores on germination produce the respective gametophytic generations. The gametophytes on maturation produce sex organs and gametes to establish the fertilization and thus to complete the life cycle. The production of different types of spores with different functions and sexuality is called Heterospory. The heterosporous condition was first evolved in Pteridophytes and it is considered as the prerequisite for seed habitat.

Learn more: Heterospory and Seed Habitat

The present post discusses the similarities and differences between microspores and megaspores with a comparison table.

Similarities between Microspores and Megaspores

Ø  Both microspores and megaspores are sexual spores.

Ø  Both are produced by the diploid sporophytic plants.

Ø  Both are haploid spores produced after reduction division of spore mother cells.

Ø  Both spores are produced in specialized structures called sporangium.

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Difference between Phase Contrast Microscopy and Differential Interference Contrast Microscopy: (Easy Short Notes)


Phase Contrast vs DIC Microscopy

Phase Contrast Microscope vs Differential Interference Contrast Microscope
(Similarities and Differences between Phase Contrast Microscope and Differential Interference Contrast (DIC) Microscope)

Phase contrast microscopy and Differential Interference Contrast (DIC) microscopy are two advanced optical light microscopy techniques to produce high contrast images of unstained and living cells. Both the microscopes utilize various contrast enhancing techniques to produce high contrast images.

Phase contrast microscopy is an optical-microscopy technique developed by Frits Zernike in 1934 to produce high contrast images of unstained live specimens. The phase contrast microscopy works by converting the phase shifts of light passing through a transparent specimen to detectable brightness changes in the image.

Differential Interference Contrast (DIC) microscopy, also called as Nomarski Interference Contrast (NIC) Microscopy, was first invented by Georges Nomarski in 1952. DIC microscopy uses more sophisticated contrast enhancing techniques than phase contrast system. It works by separating a polarized light source into two orthogonally polarized mutually coherent parts which are spatially displaced at the sample plane, and recombined before the final image formation. DIC produce more pronounced contrast difference than phase contrast image.

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Botany lecture notes

Heterospory and Seed Habitat in Pteridophytes (Short Notes)


Significance of Heterospory

Heterospory and Seed Habitat
(Origin of Seeds and Seed Habitat in Vascular Plants from Heterospory)

Heterospory is the production of two or more types of spores

Heterospory is a condition of the production of more than one type (usually two) of spores in a single plant. These two types of spore differ in their formation, structure and most importantly its functions and sexuality. In Pteridophytes, these two spores are called as Microspores and Megaspores.

(1). Microspores:

Microspores are small sized spores produced in large numbers inside the microsporangium. They are male spores which on germination produce male gametophyte.

(2). Megaspores:

Megaspores are comparatively large spores produced in limited numbers (1 to 4) inside the megasporangium. They are female spores which on germination produce the female gametophyte.

Learn more: Difference between Microspores and Megaspores

The production of two types of spores with different sexuality was first evolved in Pteridophytes. Even though, the condition of heterospory is now represented only by eight living species of Pteridophytes, they are Selaginella, Isoetus, Marsilea, Salvinia, Azolla, Pilularia, Regnellidium and Platyzoma.

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Botany lecture notes

Nodal Anatomy of Angiosperms: Unilacunar, Trilacunar and Multilacunar Node with Examples


Classification of Nodes in Plants

Nodal Anatomy of Plants with Diagram
(Leaf Gap, Leaf Trace: Unilacunar, Trilacunar and Multilacunar Nodes in Angiosperms)

Anatomy of Nodal and Inter-nodal Region are Different:

The stem of plants is differentiated into nodes and internodes. The anatomical features of the nodal region are quite different from that of the inter-nodal region. This anatomical difference is due to the presence of Vascular Supply to the leaves and branches from the main vascular cylinder of the stem.

Nodal Region of Higher Plants Posses Leaf Gaps and Leaf Traces

Each leaf that originates from the node, of higher plants possesses vascular tissue and these vascular tissues of the leaves are connected to that of the stem. A vascular strand that extends between the vascular cylinder of stem and the base of the leaf is called Leaf Trace or Foliar Trace. Even if the leaf trace possesses both xylem and phloem, the relative amount of xylem will be more in the leaf trace than phloem. Moreover, the proximal portion, (portion near the vascular cylinder of the stem) contains only the xylem. Whereas, the distal end of the leaf trace (near to the leaf base) contains both xylem and phloem. Leaf trace helps to transport water and minerals from the xylem to the leaf lamina for photosynthesis. The circulation of photosynthetic products from the leaf lamina to the phloem of the stem is also facilitated by the phloem strands in the leaf traces.

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Difference between Covalent Bond and Hydrogen Bond – Comparison Table


Compare covalent and hydrogen bond

Covalent Bond vs Hydrogen Bond
(Similarities and Differences between Covalent Bond and Hydrogen Bond)

The chemical bonds are stable attractions between atoms, ions or molecules. The formation of chemical bonds allows the formation of molecules or compounds. Chemical bonds are classified into different categories based on their formation and strength. They are categorized as Covalent bonds, Ionic bonds, Metallic bonds, Dipole-dipole interactions, London dispersion forces and Hydrogen bonds. The present post discusses about the Differences between the Covalent bond and Hydrogen bond with a Comparison Table.

Covalent bond is a primary chemical bond formed by the sharing of electron pairs. Covalent bonds are strong bonds with greater bond energy.

Hydrogen bond is a weak electrostatic attraction between the hydrogen and an electronegative atom due to their difference in electronegativity. Individual hydrogen bonds are weak bonds however, their presence in large number provide them considerable strength.

Learn more: Covalent Bond vs Ionic Bond

Learn more: Covalent Bond vs Metallic Bond

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