Plant and Animal Tissues
ICSE Class 7 · Biology · Chapter 1
What this chapter covers
- What is a tissue?
- Meristematic tissue
- Simple permanent tissues
- Complex permanent tissues
- Epithelial tissue
- Connective tissue
- Muscular tissue
- Nervous tissue
Key points
- A tissue is a group of similar cells working together for one function; tissues form organs, organs form organ systems.
- Plant tissues are meristematic (cells keep dividing) or permanent (cells have stopped dividing).
- Meristematic tissue has small, thin-walled, closely packed cells with dense cytoplasm and a large nucleus; it lies at root and shoot tips, in the cambium and at the base of grass leaves, and makes the plant grow.
- Parenchyma: living, thin-walled, loosely packed cells; stores food, makes food, keeps soft parts firm.
- Collenchyma: living cells thickened at the corners; gives support with flexibility to young stems and leaf stalks.
- Sclerenchyma: dead cells with thick, hard walls; gives strength and hardness, as in the coconut husk.
- Xylem is a complex tissue, mostly of dead tube-like cells, that carries water and minerals upward and strengthens the stem.
- Phloem is a complex tissue, mostly of living cells, that carries food from the leaves to other parts, both up and down.
- Animal tissues are epithelial, connective, muscular and nervous.
- Epithelial tissue covers and lines the body and organs; it protects, absorbs, secretes and allows exchange.
- Connective tissues include areolar, adipose, bone, cartilage, blood, ligament (bone to bone) and tendon (muscle to bone).
- Striated muscle is voluntary and moves bones; unstriated muscle is involuntary and moves food along the gut; cardiac muscle is involuntary and pumps blood without tiring.
- A neuron has a cell body, a dendron that brings messages in and an axon that carries them out.
Questions answered
What is a tissue?
A tissue is a group of similar cells that work together to perform a particular function.
State two characteristics of meristematic tissue.
Its cells are small, closely packed and thin-walled, with dense cytoplasm and a large nucleus; and they keep dividing to form new cells. (Any two features from the list are acceptable.)
Name two places where epithelial tissue is found, and one of its functions.
The outer layer of the skin and the lining of the stomach (or mouth, intestine). It protects the parts below (or absorbs or secretes).
Which simple permanent tissue has dead cells, and what is its function?
Sclerenchyma has dead cells with thick, hard walls. It gives strength and hardness to plant parts such as seed coats and the coconut husk.
Give one difference between parenchyma and collenchyma.
Parenchyma has thin walls all round and spaces between cells; collenchyma has walls thickened at the corners and few or no spaces.
Which connective tissue makes the ear flap spring back when bent, and which stores fat under the skin?
Cartilage, which is firm but flexible. Adipose tissue stores fat under the skin.
Name the tissue that carries food from the leaves to the roots. Are most of its cells living or dead?
Phloem. Most of its cells are living.
Name the connective tissue that joins a muscle to a bone, and the one that joins a bone to another bone.
A tendon joins a muscle to a bone. A ligament joins a bone to another bone.