Structural Organisation in Animals Notes: Class 11 Biology Chapter 7
Class 11 Biology Chapter 7 Structural Organisation in Animals covers animal tissues and a detailed morphological and anatomical study of an earthworm, cockroach, and frog as representative organisms.
Overview of Topics & Subtopics (Click to Jump)
1. Animal Tissues
Short Note:
• Four basic types of animal tissue: Epithelial tissue (covering/lining, protection), Connective tissue (binding and support, e.g. bone, blood, cartilage), Muscular tissue (movement; striated, unstriated, cardiac), and Nervous tissue (coordination, made of neurons).
2. Earthworm (Pheretima)
Short Note:
• A representative of phylum Annelida, characterised by metameric segmentation of the body, a closed circulatory system, and importance as a 'friend of farmers' due to soil-enriching activity.
3. Cockroach (Periplaneta)
Short Note:
• A representative of phylum Arthropoda, class Insecta, characterised by a body divided into head, thorax and abdomen, jointed appendages, and an open (haemocoelic) circulatory system.
4. Frog (Rana tigrina)
Short Note:
• A representative of phylum Chordata, class Amphibia; shows adaptations for a dual (aquatic and terrestrial) life, and undergoes metamorphosis from a tadpole (larval, aquatic) to an adult (terrestrial) form.
NCERT Textbook Exercise Questions
Diagrammatically show the different types of epithelial tissues found in the human body.
Answer: Epithelial tissues can be classified as simple (squamous, cuboidal, columnar — each single-layered) and compound/stratified (multi-layered, e.g. skin epidermis), with variants such as ciliated columnar (in respiratory tract) and glandular epithelium (secretory).
How does the study of tissues help in the industrial application of various plant and animal products?
Answer: Understanding the structure and function of tissues (such as cartilage, bone, connective tissue in animals, or fibre-yielding tissues in plants) helps in producing materials for medical implants, leather and gelatin industries, and identifying suitable tissue sources for various commercial and biomedical applications.
Draw a labelled diagram of a neuron.
Answer: A neuron consists of a cell body (containing the nucleus and cytoplasm called perikaryon), dendrites (short branched processes that receive signals), and a single long axon (that transmits impulses away from the cell body), often covered by a myelin sheath with nodes of Ranvier.
Compare the anatomy of the digestive system of a cockroach and a frog.
Answer: A cockroach's digestive system has a foregut (mouth, oesophagus, crop, gizzard for grinding food), midgut (main site of digestion/absorption, with gastric caecae), and hindgut (ileum, colon, rectum). A frog's digestive system has a buccal cavity, oesophagus, stomach (chemical digestion via gastric glands), small intestine (absorption, with bile and pancreatic secretions), and large intestine leading to a cloaca.
