SCERT KERALA TEXTBOOKS SOLUTIONS & NOTES: Class 8 Basic Science (English Medium) Chapter 02 Cell Clusters
SCERT Solutions for Class 8 Basic Science Chapterwise
Class 8 Biology - Questions and Answers
Chapter: 02 - Cell Clusters
* Human body is made up of millions of different kinds of cells like nerve cells, muscle cells, blood cells and bone cells.
* Tissues:- Groups of similar cells that have a common origin and perform specific functions.
* Animal tissues:- Epithelial tissue, Nervous tissue, Muscular tissue and Connective tissues (blood, fibrous tissue, Cartilage, bone etc.).
* Plant tissues:- Parenchyma, Collenchyma, Sclerenchyma and Vascular tissues (xylem and phloem)
* Animal tissues are developed from a single undifferentiated cell, called the zygote.
* Plant tissues are developed from rapidly dividing cells, called the meristematic cells.
* Cell differentiation:- The process by which all tissues are developed from a single cell.
[eg:- The formation of animal or plant tissues after continuous division and changes] 
* Stem cells:- specialized cells that can transform into any kind of cells through constant differentiation. Stem cells are found in the bone marrow, skin, digestive tract etc.
* Comparison between a meristematic cell and a mature plant cell,
* Importance of stem cells?
The research of stem cells can bring about miraculous changes in the treatment of blood cancer, diabetes, Parkinson disease etc., and also in the manufacture of artificial organs.
* Meristematic tissue:- Specific cells seen at the tip of the stem or root in plants. They undergo rapid division, which results in the growth of plants.
Meristematic cell
- Rapidly dividing cell
- Relatively large nucleus
- Thin primary cell wall
- More cytoplasm
- No vacuoles, Mature plant cell
- No further growth by division
- Relatively small nucleus
- Thick secondary cell wall
- Less cytoplasm
- Large vacuoles* Tissues, Function and peculiarities.
* Why are the vascular tissues (xylem and phloem) known as 'complex tissues'?
Because they are formed from different kinds of cells.
Because they are formed from different kinds of cells.
* Comparison between xylem and phloem.
* Cells combine to form tissues.
Tissues combine to form organs.
Organs combine to form organ systems.
Organ systems combine to form an organism.
[eg;- Digestive system is comprised of organs like stomach, intestines and liver. These organs are, in turn, formed by epithelial tissue, nervous tissue,
muscular tissue and connective tissues. All tissues are formed by cells]
Cells ⇾Tissues ⇾ Organs ⇾ Organ ⇾ systems ⇾ Organism ⇾ Population
⇾ Community
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