NCERT Solutions for Biology Class 11 Nutritional Disorders Notes

nutritional disorders or Diseases NCERT 1 biology

Nutritional Disorders or Diseases NCERT Class 11 Biology

Online Classes for Class 11 ScienceNutritional disorders or diseases are the physiological conditions that occur due to the lack of intake of the particular nutrients required by our body. We will discuss some of the deficiency diseases or nutritional disorders.

Protein Deficiency Diseases

Although severe protein deficiency is rare in the developed world, it is a leading cause of death in children in many poor, underdeveloped countries. There are two main syndromes associated with protein deficiencies: Kwashiorkor and Marasmus. Kwashiorkor affects millions of children worldwide. The syndrome was named because it occurred most commonly in children who had recently been weaned from the breast, usually because another child had just been born. Kwashiorkor is characterized by swelling (edema) of the feet and abdomen, poor skin health, growth retardation, low muscle mass and liver malfunction. Diets extremely low in protein do not provide enough amino acids for the synthesis of albumin. One of the functions of albumin is to hold water in the blood vessels, so having lower concentrations of blood albumin results in water moving out of the blood vessels and into tissues, causing swelling. The primary symptoms of Kwashiorkor include not only swelling, but also diarrhea, fatigue, peeling skin, and irritability. Severe protein deficiency in addition to other micronutrient deficiencies, such as folate (vitamin B9), iodine, iron, and vitamin C all contribute to the many health manifestations of this syndrome.

Children and adults with marasmus neither have enough protein in their diets nor do they take in enough calories. Marasmus affects mostly children below the age of one in poor countries. Body weights of children with Marasmus may be up to 80 percent less than that of a normal child of the same age. Marasmus is a Greek word, meaning “starvation.” The syndrome affects more than fifty million children under age five worldwide. It is characterized by an extreme emaciated appearance, poor skin health, and growth retardation. The symptoms are acute fatigue, hunger, and diarrhea.

Kwashiorkor and marasmus often coexist as a combined syndrome termed marasmic kwashiorkor. Children with the combined syndrome have variable amounts of edema and the characterizations and symptoms of marasmus. Although organ system function is compromised by under nutrition, the ultimate cause of death is usually an infection. Under nutrition is intricately linked with suppression of the immune system at multiple levels, so undernourished children commonly die from severe diarrhoea and/or pneumonia resulting from bacterial or viral infection.

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Deficiency of Vitamin D along with calcium and potassium in the body causes rickets. Rickets is characterized by weak and soft bones, bowed legs and bone deformities. Fish, fortified dairy products, liver, oil, and sunlight are some rich sources of Vitamin D. Sun is the best source of vitamin D. So one should sit in the sun during the morning hours for some time in order to take vitamin D.


Dementia, diarrhoea, dermatitis, and death are “the four Ds” that characterize Pellagra, a disease caused by the lack of Niacin or B3 in the body. The deficiency of niacin is also accompanied by a short supply of the amino acids, tryptophan, and lysine or the excessive presence of lysine in the body. Foods enriched with niacin are tuna, whole grains, peanuts, mushrooms, chicken etc. These should be consumed regularly to ward off this disease.


Alarmingly reduced levels of Vitamin C or ascorbic acid in the body can cause scurvy. Scurvy basically inhibits the production of collagen in the body which is the structural protein that connects the tissues. Decaying of the skin and gums, abnormal formation of teeth and bones, delay or inability to heal wounds and bleeding are the effects of scurvy on the body. One must consume Vitamin C by having citrus fruits like oranges, lemon, strawberry etc. and broccoli regularly in their diet.


Lack of Vitamin B1 or thiamine in the body leads to the disease called beriberi. The most common symptoms of this illness are altered muscle coordination, nerve degeneration, and cardiovascular problems. Meat, eggs, whole grains, dried beans, etc. are rich in thiamine and thus, should be consumed in proper amounts every day to avoid this painful ailment.

Learn detailed explanation of the same,  NCERT Class 11 Biology.

Xerophthalmia or Night Blindness:

Xerophthalmia or night blindness is characterized by blindness due to the poor growth, dryness, and keratinization of epithelial tissue or chronic eye infection. The cause of this disease is attributed to the deficiency of Vitamin A in the body. In worsened situations, night blindness can aggravate to complete loss of vision. The safest way to enhance the Vitamin A levels in the body is by consuming natural food sources like carrots, green and leafy vegetables, cantaloupes etc.


Iodine in the body is essential for normal cell metabolism in the body; it is the constituent of the thyroid hormones. The deficiency of iodine may cause goitre. Goitre leads to enlarged thyroid glands causing hypothyroidism, poor growth and development of infants in childhood, cretinism and even mental retardation. This disease is commonly found to occur in places having iodine deficit soil. Iodised salt and saltwater fish are rich sources of iodine and must be consumed regularly to avoid goiter.

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 Iron Deficiency Anaemia:

Iron deficiency anemia is a disease caused by the deficiency of iron in the body. It is characterized by a decrease in the red blood cell count or hemoglobin in the body, resulting in fatigue, weakness, dyspnoea, and paleness of the body. It can be easily treated by changing to a healthy diet and consuming iron supplements on a regular basis. Squashes, nuts, tofu, bran, etc. are rich sources of iron for the body.

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Problems of depression, hair loss, rashes, and mental issues are caused by the deficiency of Vitamin B7 or biotin. This deficiency can be fatal if present in an aggravated form.  Poultry products, dairy items, peanuts, nuts, etc. that are rich sources of biotin. These must be consumed along with supplements to recover and prevent these illnesses.


The deficiency of Vitamin D and calcium in the body can negatively affect the health of the bones and spine. It leads to unhealthy, soft, and brittle bones that are prone to fractures and defects in the spine structure. Bananas, spinach, milk, okra, soy, and sunlight are natural sources of Vitamin D and calcium that act to eliminate this deficiency.

It is important to follow a healthy and balanced diet in order to lead a healthy and disease-free life. Apart from a healthy diet, one must do exercise daily.


You can read more topics of Biology Class 11

Deficiency diseases caused by vitamins and minerals

Absorption And Assimilation of Digested Food

Alimentary canal and digestion

Digestion in Stomach

Structure Of Small Intestine


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Tags: Protein Deficiency Diseases; Rickets, Scurvy; Pellagra, Beriberi; Xerophthalmia or Night Blindness; Iron deficiency anemia, osteoporosis; Depression; types of nutritional disorders; list of Protein Deficiency Diseases; nutritional disorders or diseases class 11 biology ; online high school classes;  Nutritional deficiency; Nutritional Disorders Notes


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August 16, 2021

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