NCERT Solutions for Class 11 Biology Chapter 20 – Locomotion and Movement

NCERT Solutions for Class 11 Biology Chapter 20 – Locomotion and Movement will provide you with a comprehensive study of the muscular and skeletal system in humans. The NCERT Solutions offered to summarise the chapter and are quite useful for a quick revision. We have incorporated appropriate diagrams, headings and subheadings in the solutions to ensure that you are able to learn the topics easily. 

NCERT Class 11 Biology Chapter 20 is not simply a structural outline of the muscular and skeletal system. It includes the detailed functioning of the muscular system that facilitates locomotion. The topics dealt with include Types of Movement, Muscle- Types and Structure, Contractile proteins- Structure and Function, Mechanism of Muscle Contraction, Skeletal System, Joints and Disorders of Muscular and Skeletal System. There are 10 exercise questions in this chapter. 

Important Topics for NCERT solutions for Class11 Biology Chapter 20- Locomotion and Movement


The very first thing you will learn in chapter 20 of class 11 biology is locomotion. It means when we voluntarily change our place or move from one place to another. You will also learn how humans are able to move. It is because of the muscles we have. 

Types of Muscles 

Our body contains three types of muscles namely Skeletal, Visceral and Cardiac. Skeletal muscles are voluntary, Visceral muscles are involuntary and so are the Cardiac muscles. Then, you will learn about muscle fibre. You will come to know what myofibrils are. These are the smallest units of our muscles. 

Contraction of Muscles

In this section of the chapter, you will learn the process of contraction of muscles and what happens when muscles contract. There are two proteins involved in contraction of muscles – Actin and Myosin. Myosin receives a signal from the brain to produce movement. This signal causes the release of Ca++ which activates the Actin. Then Actin and Myosin attach with each other causing the stretch in the muscles and hence the movement.  

Skeletal System

You might already know what a skeletal system is but you might not be aware of the scientific terms related to skeletal. In this section, you will learn that. You will come across various new terms such as the cartilages, limb bones, axial skeleton and appendicular skeleton. You will also learn about three types of joints – fibrous, cartilaginous and synovial. If you want to know more about them you can refer to our NCERT solutions for chapter 20 of biology. 

Disorders of the Muscular and Skeletal System

Another, very important topic of the chapter is the disorder of the muscular and skeletal system. You will be learning some unfamiliar terms here such as Myasthenia Gravis, Muscular Dystrophy, Tetany, Arthritis, Osteoporosis and Gout. 

Exercise Discussion of NCERT Solutions for Chapter 20

The exercise comprises objective questions of the type ‘Name the Following, Fill in the Blanks, True or False etc. Certain questions demand detailed but precise answers, e.g. ‘Describe the important steps in muscle contraction’. The

Important Topics for NCERT Solutions for Class11 Biology Chapter 19- Excretory Products and their Elimination

In Chapter 19 of Class 11 Biology, you will learn that nitrogenous wastes accumulated in the body have to be eliminated. Various animals form different kinds of nitrogenous waste depending upon their habitat. The major nitrogenous wastes excreted are ammonia, urea and uric acid.

Structure of Excretory System in Humans 

In humans, the excretory system consists of one pair of kidneys, a pair of ureters, a urinary bladder and a urethra.

  • The nephron is the structural and functional unit of the kidney and has two portions – glomerulus and renal tubule; 
  • The glomerulus is a tuft of capillaries formed from afferent arterioles, fine branches of the renal artery. The renal tubule starts with a double-walled Bowman’s capsule and is further differentiated into a Proximal Convoluted Tubule (PCT), Henle’s Loop (HL) and Distal Convoluted Tubule (DCT); 
  • Renal corpuscle or Malpighian corpuscle is a rounded structure consisting of glomerulus surrounded by a glomerular capsule. 

Formation of Urine 

Urine formation involves three main processes, i.e., filtration, reabsorption and secretion.

  • Filtration is carried out by the glomerulus. The glomerular blood capillary pressure facilitates filtration through three membranes. 
  • The Blood is filtered so finely through these membranes, that almost all the constituents of the plasma except the proteins pass into the lumen of the Bowman’s capsule. Therefore, it is considered as a process of ultrafiltration. 
  • About 1200 ml of blood is filtered by the glomerulus per minute to form 125 ml of filtrate in the Bowman’s capsule per minute. This is called the Glomerular filtration rate. 
  • JGA (JuxtaGlomerular Apparatus) a specialised portion of the nephrons, plays a significant role in the regulation of GFR. 
  • Urine is stored in the urinary bladder till a voluntary signal from the Central Nervous System stimulates the release.
  • The process of release of urine through urethra is termed micturition.
  • Excluding kidneys, lungs, liver and skin also help in the elimination of excretory wastes.

Disorders of the Excretory System

  • Uremia: Accumulation of urea in the blood.  
  • Renal calculi: Stone or insoluble mass of crystallised salts (oxalates, etc.) formed within the kidney.
  • Glomerulonephritis: Inflammation of glomeruli of the kidney.

Haemodialysis: The process of removing waste products and excess fluid from the body. Dialysis is recommended when the kidneys are not able to adequately filter the blood. 

Exercise Discussion of NCERT Solutions for Chapter 19

A major portion of the exercise comprises objective questions of the type ‘Name the Following, Fill in the Blanks, True or False etc. Certain questions demand detailed but precise answers, e.g. explain the autoregulatory mechanism of GFR. The NCERT Solutions for class 11 biology chapter 19 gives comprehensive, step by step answers to such questions. 

Benefits of CBSE NCERT Class 11 Biology Chapter 19 by Instasolv

To give you the ultimate opportunity to learn the varied concepts associated with the excretory system in an elaborate and easy-to-understand manner, the NCERT solutions for Class 11 biology Chapter 19 has been thoroughly prepared by the Instasolv team. We assure you that you will be able to score good marks in this chapter without much difficulty.

chapter 20 gives comprehensive, step by step answers to such questions. 

A major chunk of the exercise deals with ‘differentiate between’ questions, for example, ‘distinguish between actin and myosin’. There is one question related to the diagram of the sarcomere of skeletal muscle. The fill in the blanks questions of the chapter are very interesting as they help clear all your concepts related to muscles in humans.

Benefits of NCERT Solutions for Class 11 Biology Chapter 20 by Instasolv

Chapter 20 of NCERT Class 11 Biology book is quite interesting yet difficult to understand because of a lot of theoretical concepts involved. We have tried to simplify all the explanations and definitions in our NCERT Class 11 Biology Chapter 20 Solutions. We have also ensured that you are able to understand all the diagrams of the chapter. All our answers are checked multiple times to ensure that you receive the best solutions.