CBSE Class 11 Biology NCERT Solutions Chapter 7: Structural Organisation in Animals
This chapter delves into the structural organisation of animals, focusing on key examples like the earthworm and the cockroach. The NCERT Solutions for Class 11 Biology, Chapter 7, provide clear explanations and diagrams for understanding the complex systems within these organisms. Key topics include the common name of Periplaneta americana, the number and function of spermathecae in earthworms, the location of ovaries in cockroaches, the number of abdominal segments in cockroaches, and the location and function of Malpighian tubules. Additionally, the solutions explain the function of nephridia and their different types in earthworms, along with labelled diagrams of the reproductive organs of an earthworm and the alimentary canal of a cockroach. These solutions are designed to help students grasp the intricate details of animal anatomy and physiology, aiding in their exam preparation by offering step-by-step explanations and visual aids.
Quick info
| Board | CBSE |
|---|---|
| Class | Class 11 |
| Subject | Biology |
| Session | 2026 |
| Language | English |
| Type | NCERT Solutions |
| Chapter | Chapter 7: Structural Organisation in Animals |
Chapter summary
Chapter 7 of the Class 11 Biology NCERT Solutions focuses on the structural organisation in animals, using earthworms and cockroaches as primary examples. It covers essential aspects of their anatomy, including excretory and reproductive systems, and digestive tracts. The solutions provide answers to specific questions about the number of segments, the function of organs like nephridia and malpighian tubules, and detailed labelled diagrams for better visualisation. This chapter is crucial for understanding comparative anatomy and physiological adaptations in animals.
Learning outcomes
- Identify the common name of Periplaneta americana.
- Describe the number and function of spermathecae in earthworms.
- Locate the ovaries in a cockroach.
- State the number of abdominal segments in a cockroach.
- Identify the location and function of malpighian tubules.
- Explain the function of nephridia in earthworms.
- Differentiate between the types of nephridia based on their location in earthworms.
- Interpret labelled diagrams of the reproductive organs of an earthworm and the alimentary canal of a cockroach.
Topics covered
Paper topics
- Structural Organisation in Animals
- Periplaneta americana
- Earthworm Anatomy
- Spermathecae
- Nephridia
- Cockroach Anatomy
- Ovaries in Cockroach
- Abdominal Segments
- Malpighian Tubules
- Alimentary Canal of Cockroach
- Reproductive Organs of Earthworm
- Excretory System
Important topics
- Earthworm Excretory and Reproductive Systems
- Cockroach Digestive and Reproductive Systems
- Function and Location of Malpighian Tubules
- Types and Functions of Nephridia
- Diagrammatic Representation of Organs
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Questions and Solutions
Question 1: Answer in one word or one line.
Give the common name of Periplaneta americana.
(i) How many spermathecae are found in earthworm?
(ii) What is the position of ovaries in the cockroach?
(iii) How many segments are present in the abdomen of cockroach?
(iv) Where do you find malpighian tubules?
The common name of Periplaneta americana is the American cockroach.
(i) Four pairs of spermathecae are present in earthworms. These are located in the inter-segmental grooves between the 6th and 9th segments and are responsible for receiving and storing spermatozoa during copulation.
(ii) In a cockroach, the pair of ovaries is located between the 12th and 13th abdominal segments.
(iii) The abdomen in both male and female cockroaches consists of ten segments.
(iv) Malpighian tubules are the principal excretory organs found in cockroaches. They are located in the posterior part of the alimentary canal, extending into the haemocoel.
Question 2: Answer the following:
(i) What is the function of nephridia?
(ii) How many types of nephridia are found in earthworm based on their location?
(i) Nephridia are the segmentally arranged excretory organs in earthworms that perform the function of osmoregulation and excretion of nitrogenous wastes.
(ii) Based on their location and structure, three types of nephridia are found in earthworms:
1. Septal nephridia: These are found on both sides of the inter-segmental septa, starting from the 15th segment onwards. They open into the lumen of the intestine.
2. Integumentary nephridia: These are attached to the lining of the body wall from the third segment to the last segment. They open on the body surface and excrete waste directly to the exterior.
3. Pharyngeal nephridia: These occur in three paired tufts located in the 4th, 5th, and 6th segments. They are connected by a duct to the pharynx.
Question 3: Draw a labelled diagram of the reproductive organs of an earthworm.
Draw a labelled diagram of the reproductive organs of an earthworm.
A labelled diagram of the reproductive organs of an earthworm is provided below, illustrating structures such as testes, spermatic funnels, vasa deferentia, seminal vesicles, spermathecae, ovaries, ovarian funnels, prostate glands, and accessory glands.
Question 4: Draw a labelled diagram of the alimentary canal of a cockroach.
Draw a labelled diagram of the alimentary canal of a cockroach.
The alimentary canal of a cockroach is a long, coiled tube differentiated into the foregut, midgut, and hindgut. The provided diagram shows key parts including the salivary glands, pharynx, oesophagus, crop, gizzard, hepatic caeca, mesenteron (midgut), malpighian tubules, ileum, colon, rectum, and anus.
Common mistakes
- Confusing the number of spermathecae or their exact location.
- Incorrectly identifying the position of ovaries in cockroaches.
- Misinterpreting the function or location of malpighian tubules.
- Difficulty in recalling the different types of nephridia and their specific roles.
- Errors in labelling or interpreting the provided biological diagrams.
Revision tips
- Focus on memorising the specific numbers and locations mentioned for organs in earthworms and cockroaches.
- Pay close attention to the labelled diagrams; try to redraw them from memory.
- Understand the primary function of each organ discussed, especially excretory and reproductive structures.
- Use the provided answers to cross-check your understanding after attempting the questions yourself.
- Relate the structural details to the overall physiological functions of the organisms.
Practice MCQs
Q1. What is the common name of Periplaneta americana?
Explanation: Periplaneta americana is the scientific name for the common American cockroach.
Q2. How many pairs of spermathecae are typically found in an earthworm?
Explanation: Earthworms possess four pairs of spermathecae, which are crucial for storing spermatozoa received during copulation.
Q3. In a cockroach, between which abdominal segments are the ovaries located?
Explanation: The pair of ovaries in a cockroach is situated between the 12th and 13th abdominal segments.
Q4. Malpighian tubules in cockroaches primarily function as:
Explanation: Malpighian tubules are the main excretory organs in cockroaches, filtering waste from the haemolymph.
Q5. Which type of nephridia in earthworms opens directly onto the body surface?
Explanation: Integumentary nephridia are attached to the body wall and open on the surface, functioning in excretion.
Frequently asked questions
What is the main focus of Chapter 7: Structural Organisation in Animals for Class 11 Biology?
This chapter focuses on the detailed structural organisation of animals, using the earthworm and the cockroach as key examples to illustrate various organ systems like digestive, circulatory, respiratory, nervous, excretory, and reproductive systems.
What are the common names of the animals discussed in these NCERT Solutions?
The common name for Periplaneta americana is the American cockroach. The solutions also extensively discuss the earthworm.
How do these NCERT Solutions help in understanding the diagrams?
The solutions provide labelled diagrams for the reproductive organs of the earthworm and the alimentary canal of the cockroach, helping students visualise and understand the arrangement and connections of different parts.
What is the role of Malpighian tubules mentioned in the solutions?
Malpighian tubules are identified as the primary excretory organs in cockroaches, responsible for filtering waste products from the haemolymph and forming uric acid.
Are the functions of nephridia explained in the solutions?
Yes, the solutions explain the function of nephridia as segmentally arranged excretory organs in earthworms and detail the three types based on their location: septal, integumentary, and pharyngeal.
How can these solutions be used for exam revision?
These solutions offer clear, concise answers to exercise questions, explain key concepts, and provide essential diagrams, making them ideal for revising the structural details and functions of organs in earthworms and cockroaches for exams.
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