Science Class 6 part-I NCERT

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    1. Food - Vitamin A keeps our skin and eyes healthy. Vitamin C helps body to fight against many diseases (gets easily destroyed by heat during cooking).
    2. Vitamin D helps our body to use calcium for bones and teeth.
    3. Dietary fibres are also known as roughage. Roughage is mainly provided by plant products in our foods.
    4. Diseases that occur due to lack of nutrients over a long period are called deficiency diseases.

    Vitamin

    Disorder

    Symptoms

    Foods

    Vitamin A

    Loss of vision

    Night blindness, sometimes complete loss

    Milk, eggs, green vegetables

    Vitamin B1

    Beriberi

    Weak muscles and very little energy to work

    Many different foods - whole grains, cereals

    Vitamin B12

     

    to make red blood cells

    found naturally in fish, red meat, poultry, milk, cheese, and eggs. 

    Vitamin C

    Scurvy

    Bleeding gums

    Needed for collagen, citrus food

    Vitamin D

    Rickets

    Bones become soft and bent

    Sunlight, egg yolk, oily fish

    Vitamin E

     

    very rare condition

    Antioxidant, vegetable oils, green leafy vegetables

    Calcium

    Bone & tooth decay

     

     

    Iodine

    Goiter

    Glands in neck appear swollen

     

    Iron

    Anemia

    Weakness

     
    1. Fabrics are made up of yarns and yarns are further made up of fibers. Cotton and jute are examples of fibers obtained from plants. Wool and silk fibers are obtained from animals. Synthetic fibers are polyester, nylon and acrylic.
      1. Cotton - boll is fruit of cotton, fibers are separated from the seeds by combing. This process is called ginning of cotton
      2. Jute fiber is obtained from stem of the jute plant

    Fabric from yarns is made by weaving and knitting. Process of arranging two sets of yarns together to make a fabric is called weaving. In knitting, a single yarn is used to make a piece of fabric

    1. When the heavier component in a mixture settles after water is added to it, the process is called sedimentation. When the water (along with the dust) is removed, the process is called decantation. More of a substance can be dissolved in a solution by heating it
    2. Most plants can be classified into three categories: herbs, shrubs and trees. Plants with weak stems that cannot stand upright and spread on the ground are called creepers, while those that take support on neighboring structures and climb up are called climbers. Part of a leaf by which it is attached to the stem is called petiole. The broad, green part of the leaf is called lamina
      1. Water comes out of leaves in the form of vapor by a process called transpiration. Plants release a lot of water into the air through this process.

    Plants having leaves with reticulate venation have tap roots while plants having leaves with parallel venation have fibrous roots.

    1. Muscles work in pairs. When one of them contracts, the bone is pulled in that direction. The other muscle of the pair relaxes. A muscle can only pull. It cannot push. Thus, two muscles have to work together to move a bone.
      1. Earthworm does not have bones. It has muscles which help to extend and shorten the body.
      2. Snail shell is a single unit and does not help in moving from place to place. It has to be dragged along. Snails move with the help of a muscular foot
      3. Cockroaches walk and climb as well as fly in the air. They have three pairs of legs
      4. Snakes have a long backbone. They have many thin muscles.
      5. Fish swim by forming loops alternately on two sides of the body
    2. Adaptation -
      1. Desert plants lose very little water through transpiration. The leaves in desert plants are either absent, very small, or they are present in the shape of spines. Photosynthesis in these plants is carried out by stems.
      2. Mountains - trees are normally cone shaped and have sloping branches. The leaves of some of these trees are needle-like. This helps the rainwater and snow to slide off easily.
      3. Dolphins breathe in air through nostrils or blowholes that are located on the upper parts of their heads. This allows them to breathe in air when they swim near the surface of water.
      4. In aquatic plants, roots are much reduced in size and their main function is to hold the plant in place. Stems of these plants are long, hollow and light. The stems grow up to the surface of water while the leaves and flowers, float on the surface of the water
      5. Some animals may have different mechanisms for the exchange of gases, which is a part of the respiration process. For example, earthworms breathe through their skin. Fish have gills for using oxygen dissolved in water
      6. Respiration is a process that takes place in seeds even when some of the other life processes may not be very active

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