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Forests: Our Lifeline | Part 1 | Forests, Shrubs, Herbs, Creepers & Climbers

This video explains about forests, shrubs, herbs, creepers and climbers from NCERT science class VII chapter 17. It explains in Gujarati with english terms.


Forests serve as green lungs and water purifying system in nature.

Shrubs are smaller than trees and it has several main stems arising at or near ground. It is highly branched. Examples of shrubs are rose, henna, lemon etc.

Herbs are plants that does not have woody stem and they are smaller than shrubs. Examples of herbs are coriander, mint, parsley, basil etc.

Creepers are plants that grows along the ground and they have fruits close to ground because they have weak stem and cannot stand upright so they spread on ground. Examples of creepers are watermelon, pumpkin, muskmelon etc.

Climbers are plants with weak stem and they need support to climb or grow upwards. Examples of climbers are money plant, pea plant, beans plant etc.

In the forest, trees can be covered with creepers and climbers.

00:06 introduction to forests

01:51 forests as green lungs

04:19 Shrubs

05:16 Herbs

08:14 Creepers

10:39 Climbers

(Forests, Shrubs, Herbs, Creepers and Climbers)

You can find this chapter online on NCERT e-book here : NCERT Science Class VII Chapter 17.

If you want learn Genetics visit this page.

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Antigen Processing and Presentation | Part II | The Endocytic Pathway

Antigen Processing and Presentation | Part II | The Endocytic Pathway

Antigen processing and presentation is when a foreign protein antigen is degraded into peptides and becomes MHC associated peptide fragments on a infected cell surface for display to T cells. This is because , in order for a foreign protein antigen to be recognised by T cells, it must be degraded into small antigenic peptides which forms complexes with Class I or Class II MHC molecule. T cells on their own cannot recognise the antigen alone, it must be presented on MHC molecule.

When an Antigen Presenting Cell (APC) such as macrophages, dendritic cells or B cells, takes up the exogenous antigen by phagocytosis or endocytosis, It will degrade it into peptides within the compartments of the endocytic processing pathway and makes antigen Class II MHC complex which would display antigen to T helper cells.

Have you ever wondered how antigen presenting cell (APC) does not get confused between whether to present Ag on MHC I or MHC II since it can express both? Let’s find out about it and more in this video.

@ 00:14 introduction, @ 09:51 endocytic pathway – overview, @ 13:26 explanation of how the APC knows on which MHC molecule to display the Ag @ 17:50 explanation of endocytic pathway.

Binding of antigenic peptide to MHC II molecule in exchange of CLIP (Class II Associated Invariant Chain Peptide) requires a non classical MHC II molecule called HLA-DM.

Here’s the first part Antigen Processing and Presentation | Part I | The Cytosolic Pathway?