________________
(e) Mammals the highest group in animal kingdom; warm-blooded and terrestrials, a few have become secondarily aquatic and some have become aerial; have many glands (sweat, scent) including the mammary glands in females which secrete milk for nourishing the young; ears have external pinna, eyes have eyelids; heart is 4-chamber; respiration is by lungs only; Cerebral hemispheres are well developed reaching their maximum in human beings; male has a copulatory organ—the penis; fertilization is internal, the embryo is connected to the wall of the uterus by the placenta and are viviparous. Examples: rabbits, rats, bats, squirrels, guinea pigs, cattle, horses; cats—lions, tigers; dogs—wolf, foxes; elephants, giraffes, dolphins, whales, etc. and humans. NUTRITION
Life cannot exist without a source of energy. Without energy plants could not grow and man could not work. Plants use the energy of sun to make foods and man uses the energy in foods to perform his various activities.
All living organisms require a constant supply of energy for their day-to-day activities; to make good the wear and tear of tissues and also to add to the protoplasm, the material necessary for growth. A constant supply of energy is needed in much the same way a steam engine must have a continuous supply of steam. If steam was not available, the engine would not operate.
This energy is obtained from food which includes proteins, carbohydrates, fats, vitamins, water and various inorganic salts. These are referred to as nutrients. Water and mineral salts are inorganic compounds and the rest are organic.
Nutrition involves mainly four steps:
1. Ingestion or intake of food, 2. Digestion or conversion to a simpler form, 3. Assimilation or extraction of energy from the food, and 4. Egestion or excretion of waste matter.
- 28 :--- Jain Education International
For Personal & Private Use Only
JAIN BIOLOGY
www.jainelibrary.org
