NCERT Solutions for Class 11 Biology Chapter 19: Excretory Products and their Elimination

NCERT Solutions for Class 11 Biology Chapter 19 Excretory Products and their Elimination are provided in the article below. It covers all the important definitions, concepts, and methodologies that will be really beneficial for the students. The important topics that are included in this chapter are:

Expected no. of Questions: 1-2 questions of around 2 marks.

Download PDF: NCERT Solutions for Class 11 Biology Chapter 19 Excretory Products and their Elimination

NCERT Solutions for Class 11 Biology Chapter 19

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Class 11 Biology Chapter 19 Excretory Product and Their Elimination: Important Topics

Excretion is the biological process by which an organism rids itself of the excess waste products and the nitrogenous by-products of metabolism through the urethra. Moreover, through this process, organisms control osmotic pressure - the balance between inorganic ions and water - and maintain acid-base balance. In this way, homeostasis is promoted, the constancy of the organism’s internal environment.

  • Modes of Excretion

There are five modes of excretion found in animals based on the excretory product. They are:

  • Ammonotelism (Type of excretion- ammonia)
  • Ureotelism (Type of excretion – urea)
  • Uricotelism (Type of excretion – uric acid)
  • Aminotelism (Type of excretion – amino acids)
  • Guanotelism (Type of excretion – guanine)
  • Human Excretory System

Human Excretory System is that in complex organisms including humans, there is a specialized system for excretion. The human excretory system comprises organs that facilitate the removal of nitrogenous wastes from the body. 

The human excretory system organs include:

  • A pair of kidneys: 
  • A pair of ureters:
  • A urinary bladder: 
  • A urethra: 
  • Urine Formation

In the human body, the kidneys filter unwanted substances from the blood and excrete them in the form of urine. There are three main steps of urine formation: glomerular filtration, reabsorption, and secretion. All these three processes ensure that only waste and excess water are removed from our body.

Chapter Related Links:

Human Excretory System Function of the tubules Mechanism of concentration of the filtrate
Ammonotelism Role of other organs in excretion Micturition
Osmoregulation Urine Formation Atrial Fibrillation

CBSE Class 11 Biology Study Guides:

CBSE CLASS XII Related Questions

  • 1.

    Assertion (A) : The pyramid of biomass in a pond aquatic ecosystem is always inverted.

    Reason (R) : The biomass of consumers like fishes far exceeds that of the producers like phytoplanktons.

      • Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
      • Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
      • Assertion (A) is true, but Reason (R) is false.
      • Assertion (A) is false, but Reason (R) is true.

    • 2.

      A student performed some crosses in plants and represented the result in the form of bar graphs as shown below. Each graph displays the phenotypic proportion of the progeny. Study the graphs and answer the questions :

      (c) What conclusion can you draw from the results of bar graphs of crosses I and II ? Name the genetic principle illustrated.


        • 3.
          In Pisum sativum, the flower colour may be violet (V) or white (v). What proportion of the offspring in a cross of "VV × vv" would be expected to be violet?

            • 25%
            • 50%
            • 75%
            • 100%

          • 4.

            "Indo-Burma" is considered as a hotspot. What is meant by the term "hotspots" in biodiversity ? List two criteria used for determining a "hotspot". Name any two hotspots of India.


              • 5.
                Assertion (A): The embryo with 8 to 16 blastomeres is called a morula.
                Reason (R): The morula continues to divide and transform into trophoblast.

                  • Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
                  • Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
                  • Assertion (A) is true, but Reason (R) is false.
                  • Assertion (A) is false, but Reason (R) is true.

                • 6.

                  Assertion (A) : The two chains of DNA have antipolarity.

                  Reason (R) : In one chain of DNA, ribose sugar at \(5^{\prime}\) end consists of a free phosphate moiety, while at the other end, the ribose sugar has free \(3^{\prime}\) - OH group.

                    • Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
                    • Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
                    • Assertion (A) is true, but Reason (R) is false.
                    • Assertion (A) is false, but Reason (R) is true.
                  CBSE CLASS XII Previous Year Papers

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