Introduction

Components of food necessary for the body are called Nutrients. Organisms that prepare food themselves from simple substances are called Autotrophs and animals that take in ready-made food made by plants are called Heterotrophs.

• Herbivores: Animals that eat only plants.
• Carnivores: Animals that eat other animals.
• Omnivores: Animals that eat both plants and animals.

Types of nutrients:

• Carbohydrates
•  Fats
•  Proteins
•  Vitamins
•  Minerals
•  Dietary Fibers and Water

Carbohydrates and Fats

Carbohydrates and fats are energy-giving food. Carbohydrates give less energy than fats. Animal fats are saturated fatty acids, which are harmful to health. We should choose unsaturated fatty acids for cooking. Trans fats are unsaturated fats that damage the heart.

Proteins

Proteins are body-building foods. Proteins are polypeptides i.e. linear chains of amino acids linked by peptide bonds. Enzymes are proteins that perform the role of biological catalysts.
Receptors are proteins that perform functions related to communication systems in the body.
Collagen is the most abundant protein in the animal world and
Ribulose bisphosphate Carboxylase-Oxygenase (RuBisCO) is the most abundant protein in the whole of biosphere. Protein deficiency causes kwashiorkor and Marasmus.

Vitamin and Minerals

Vitamin A, E, and C are antioxidants that absorb free radicals. Vitamins and minerals deficiency can cause the diseases mentioned in the table.

Table: Deficiency diseases

 

Vitamins or minerals	Disease
Vitamin A	Night blindness / Xeropthalmia
Vitamin B1	Beri Beri
Vitamin C	Scurvy
Vitamin D	Rickets
Vitamin E	Anemia / Loss of fertility
Vitamin K	Bleeding
Calcium	Bone and tooth decay
Iron	Anemia
Iodine	Goiter

Note: Mercury poisoning causes mina mata disease and cadmium poisoning causes itai-itai.

Test to Detect Iodine, Proteins, and  Fats

1. 1. Test for starch: IODINE TEST
      • Take a small food quantity and add dilute iodine solution if it turns blue-black then it has starch
   2. Test for proteins: COPPER SULPHATE + CAUSTIC SODA TEST
      • Take a small food quantity and add copper sulfate and caustic soda solution if it turns violet then it has proteins
   3. Test for fats: PAPER TEST

1. • Take a small food quantity and wrap it in paper and crush it. Observe the oil patch in light

Dietary Fibers and Water

Roughage or dietary fibers are present in plant products like whole grains, pulses, potatoes, fresh fruits, and vegetables. Don’t have nutrients but helps to get rid of undigested food.

Human body and nutrients

Digestion is a process in which complex components of food are broken into simpler substances.
Saliva breaks down starch into sugars. The stomach secretes mucous, hydrochloric acid, and digestive juices. The mucous protects the lining of the stomach, acid kills the bacteria and digestive juices break proteins into simpler substances.
The liver is the largest gland in the body. It secretes bile stored in the gall bladder, bile is important in the digestion of fats. It produces cholesterol [lipoprotein].
Low-density cholesterol is bad and high-density cholesterol is good.

Humans can’t digest cellulose. The temperature of a human body is 35-42° Celsius.

Miscellaneous

Starfish feed on animals that are covered by a calcium carbonate shell. The shell is popped open and then the starfish puts its stomach out of its mouth to eat the soft animal inside. The stomach then goes back inside and then the food is slowly digested.

The small intestine is lined with villi which help in the absorption of food. The small intestine is 7.5m and the large intestine is 1.5m.     In herbivores, the small intestine is longer to digest cellulose. In carnivores, the small intestine is smaller as meat is easily digested.