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Biology Ncert Notes 2023-2024 : Mandakini Study Institute - Patna
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Biology Ncert Notes 2023-2024

#.1. Components of Food ::

  1. The major nutrients in our food are carbohydrates, proteins,fats, vitamins and minerals. In addition, food also contains dietary fibres and water.
  2. Carbohydrates and fats mainly provide energy to our body.
  3. Proteins and minerals are needed for the growth and the maintenance of our body.
  4. Vitamins help in protecting our body against diseases.
  5. Balanced diet provides all the nutrients that our body needs, in right quantities, along with adequate amount of roughage and water.
  6. Deficiency of one or more nutrients in our food for a long time may cause certain diseases or disorders.

#.2. Getting to Know Plants ::

  1. Plants are usually grouped into herbs, shrubs and trees based on their height, nature of stem and branches.
  2. The stem bears leaves, flowers and fruits.
  3. Leaf usually has a petiole and lamina.
  4. The pattern of veins on the leaf is called venation. It can be reticulate or parallel.
  5. Leaves give out water vapour through the process of transpiration.
  6. Green leaves make their food by the process of photosynthesis using carbon dioxide and water in the presence of sunlight.
  7. Roots absorb water and minerals from the soil. They also anchor theplant firmly in the soil.
  8. Roots are mainly of two types: tap root and fibrous root.
  9. Plants having leaves with reticulate venation have tap roots while plants having leaves with parallel venation have fibrous roots.
  10. The stem conducts water from roots to the leaves (and other parts) and food from leaves to other parts of the plant.
  11. The parts of a flower are sepals, petals, stamens and pistil.

#.3. Body Movements ::

  1. Bones and cartilage form the skeleton of the human body. It gives theframe and shape to the body and helps in movement. It protects the inner organs.
  2. The human skeleton comprises the skull, the back bone, ribs and the breast bone, shoulder and hipbones, and the bones of hands and legs.
  3. The bones are moved by alternate contractions and relaxations of two sets of muscles.
  4. The bone joints are of various kinds depending on the nature of joints and direction of movement they allow.
  5. Strong muscles and light bones work together to help the birds fly. They fly by flapping their wings.
  6. Fish swim by forming loops alternately on two sides of the body.
  7. Snakes slither on the ground by looping sideways. A large number of bones and associated muscles push the body forward.
  8. The body and legs of cockroaches have hard coverings forming an outer skeleton. The muscles of the breast connected with three pairs of legs and two pairs of wings help the cockroach to walk and fly.
  9. Earthworms move by alternate extension and contraction of the body using muscles. Tiny bristles on the underside of the body help in gripping the ground.
  10. Snails move with the help of a muscular foot.

#.4. The Living Organisms — Characteristics and Habitats ::

  1. The surroundings where plants and animals live, is called their habitat.
  2. Several kinds of plants and animals may share the same habitat.
  3. The presence of specific features and habits, which enable a plant or an animal to live in a particular habitat, is called adaptation.
  4. There are many types of habitats, however, these may be broadly grouped as terrestrial (on the land) and aquatic (in water).
  5. There is a wide variety of organisms present in different habitats.
  6. Plants, animals and microorganisms together constitute biotic components.
  7. Rocks, soil, air, water, light and temperature are some of the abiotic components of our surroundings.
  8. Living things have certain common characteristics — they need food, they respire and, excrete, respond to their environment, reproduce, grow and show movement.

#.5. Nutrition in Plants ::

  1. All organisms need food and utilise it to get energy for growth and maintenance of their body.
  2. Green plants synthesise food for themselves by the process of photosynthesis. They are autotrophs.
  3. Plants like Cuscuta are parasites. They take food from the host plant.
  4. Plants use simple chemical substances like carbon dioxide, water and minerals for the synthesis of food.
  5. Chlorophyll, water, carbon dioxide and sunlight are the essential requirements for photosynthesis.
  6. Complex chemical substances such as carbohydrates are the products of photosynthesis.
  7. Solar energy is absorbed by the chlorophylls present in leaves/plants.
  8. Oxygen is produced during photosynthesis.
  9. Oxygen released in photosynthesis is utilised by living organisms for their survival.
  10. Many fungi derive nutrition from dead and decaying matter. They are saprotrophs.
  11. A few plants and all animals are dependent on others for their nutrition and are called heterotrophs.

#.6. Nutrition in Animals ::

  1. Animal nutrition includes nutrient requirement, mode of intake of food and its utilisation in the body.
  2. The human digestive system consists of the alimentary canal and secretory glands. It consists of the (i) buccal cavity, (ii) oesophagus,
  3. (iii) stomach, (iv) small intestine, (v) large intestine ending in rectum and (vi) anus. The main digestive glands which secrete digestive juices
  4. are (i) the salivary glands, (ii) the liver and (iii) the pancreas. The stomach wall and the wall of the small intestine also secrete digestive juices.
  5. The modes of feeding vary in different organisms.
  6. Nutrition is a complex process involving: (i) ingestion, (ii) digestion, (iii) absorption, (iv) assimilation and (v) egestion.
  7. Digestion of carbohydrates, like starch, begins in the buccal cavity. The digestion of protein starts in the stomach. The bile secreted from the
  8. liver, the pancreatic juice from the pancreas and the digestive juice from the intestinal wall complete the digestion of all components of food
  9. in the small intestine. The digested food is absorbed in the blood vessels from the small intestine.
  10. The absorbed substances are transported to different parts of the body. Water and some salts are absorbed from the undigested food in the large intestine.
  11. The undigested and unabsorbed residues are expelled out of the body as faeces through the anus.
  12. The grazing animals like cows, buffaloes and deer are known as ruminants. They quickly ingest, swallow their leafy food and store it in the rumen. Later, the food returns to the mouth and the animal chews it peacefully.
  13. Amoeba ingests its food with the help of its false feet or pseudopodia. The food is digested in the food vacuole.

#.7. Respiration in Organisms ::

  1. Respiration is essential for survival of living organisms. It releases energy from the food.
  2. The oxygen we inhale is used to breakdown glucose into carbon dioxide and water. Energy is released in the process.
  3. The breakdown of glucose occurs in the cells of an organism (cellular respiration).
  4.  If the food is broken down with the use of oxygen, it is called aerobic respiration. If the breakdown occurs without the use of oxygen, the respiration is called anaerobic respiration.
  5. During heavy exercise when the supply of oxygen to our muscle cells is insufficient, food breakdown is by anaerobic respiration.
  6. Breathing is a part of the process of respiration during which an organism takes in the oxygen-rich air and gives out air rich in carbon dioxide. The respiratory organs for the exchange of gases vary in different organisms.
  7. During inhalation, our lungs expand and then come back to the original state as the air moves out during exhalation.
  8. Increased physical activity enhances the rate of breathing.
  9.  In animals like cow, buffalo, dog and cat the respiratory organs and the process of breathing are similar to those in humans.
  10. In earthworm, the exchange of gases occurs through the moist skin. In fishes it takes place through gills and in insects through the tracheae.
  11.  In a plant the roots take in air present in the soil. Leaves have tiny pores called stomata through which they exchange gases. The breakdown of glucose in the plant cells is similar to that in other living beings.

#.8. Transportation in Animals and Plants ::

  1. In most animals the blood that circulates in the body distributes food and oxygen to different cells of the body. It also carries waste products from different parts of the body for excretion.
  2. Circulatory system consists of the heart and blood vessels.
  3. In humans, blood flows through arteries and veins and the heart acts as a pumping organ.
  4. Blood consists of plasma, RBC, WBC and platelets. Blood is red due to the presence of a red pigment, haemoglobin.
  5. The human heart beats about 70–80 times per minute in an adult person. This is called heart rate.
  6. Arteries carry blood from the heart to all parts of the body.
  7. Veins carry blood from all parts of the body back to the heart.
  8. Removal of waste products from the body is called excretion.
  9. Excretory system of humans consists of two kidneys, two ureters, a urinary bladder, and urethra.
  10. Salts and urea are removed along with water as sweat.
  11. Fish excrete waste substances such as ammonia which directly dissolve in water.
  12. Birds, insects and lizard excrete uric acid in semi-solid form.
  13. Water and mineral nutrients are absorbed by roots from the soil.
  14. Nutrients are transported along with water to the entire plant via the vascular tissue called xylem.
  15. The vascular tissue for the transport of food to the various parts of the plant is phloem.
  16. A lot of water is lost by plants in the form of vapour through stomata during transpiration.
  17. Transpiration generates a force which pulls up water absorbed by the roots from the soil, to reach the stem and leaves.

#.9. Reproduction in Plants ::

  1. All organisms multiply or reproduce their own kind.
  2. In plants there are two modes of reproduction, asexual and sexual.
  3. There are several methods of asexual reproduction such as fragmentation, budding, spore formation and vegetative propagation.
  4. Sexual reproduction involves the fusion of male and female gametes.
  5. In vegetative propagation new plants are produced from different vegetative parts such as leaves, stems and roots.
  6. Flower is the reproductive part of a plant.
  7. A flower may be unisexual with either the male or the female reproductive parts.
  8. A bisexual flower has both the male and the female reproductive parts.
  9. The male gametes are found inside the pollen grains and female gametes are found in the ovule.
  10. Pollination is the process of transfer of pollen grains from the anther of one flower to the stigma of the same or another flower.
  11. Pollination is of two types, self-pollination and cross-pollination. In self-pollination, pollen grains are transferred from the anther to the stigma of the same flower. In cross-pollination, pollen grains are transferred from the anther of one flower to the stigma of another flower of the same kind.
  12. Pollination takes place in plants with the help of wind, water and insects.
  13. The fusion of male and female gametes is called fertilisation.
  14. Fertilised egg is called zygote. Zygote develops into an embryo.
  15. Fruit is the mature ovary whereas ovule develops into a seed, which contains the developing embryo.
  16. Seed dispersal is aided by wind, water and animals.
  17. Seed dispersal helps the plants to (i) prevent overcrowding, (ii) avoid competition for sunlight, water and minerals and (iii) invade new habitats.