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Earth happens to be the only known planet having a life. There are beings who live, die and become part of nature again. The living organism can be differentiated from the inanimate entities on various parameters of life processes.

Life Processes

  • The maintenance of living organisms is essential even if they are moving, resting, or even sleeping. The processes which together perform the function of maintenance of ‘life’ are known as life processes.
  • The various life processes which take place in living organisms are called metabolic activities or metabolism. These life processes can either be anabolic or catabolic in nature.
  • Nutrition, respiration, transportation, and excretion are some of the life processes that are essential for the functioning as well as maintenance of living organisms.

Life ProcessesLife Processes

Nutrition

  • Nutrition is defined as a process by which living organisms procure food or synthesize it and convert it into simple absorbable form by a series of biochemical processes.
  • Nutrient can be defined as a substance that an organism obtains from its surroundings and use as a source of energy as well as providing raw materials for the biosynthesis of body constituents.
  • There are two basic modes of nutrition: autotrophic and heterotrophic.

Life Processes- 1 Chapter Notes | Science Class 10

  • In Autotrophic nutrition, organisms manufacture their food from simple inorganic raw materials. The majority of green plants are capable of manufacturing their food in the presence of light by using water and carbon dioxide.
  • Heterotrophic organisms cannot prepare their food. They are dependent on plants, animals or on dead decaying organic materials for their food. Saprophytes derive their nourishment from dead decaying matter.

Life Processes- 1 Chapter Notes | Science Class 10

  • Holozoic nutrition is a mode of nutrition that involves swallowing solid food material. Ingestion, digestion, absorption, assimilation, and egestion are the various steps involved in holozoic nutrition.

Question for Chapter Notes: Life Processes- 1
Try yourself:Green plants use ____________ mode of nutrition.
View Solution

Photosynthesis

Photosynthesis can be defined as the synthesis of organic compounds (carbohydrates) from CO2 and H2using radiant energy or solar energy by chlorophyll molecules.
The process of photosynthesis involves two phases: Light Reaction and Dark Reaction.

The following events occur during the process of photosynthesis:

  • Absorption of light energy by chlorophyll.
  • Conversion of light energy to chemical energy as well as splitting of water molecules into hydrogen and oxygen.
  • Reduction of carbon dioxide to carbohydrates.

PhotosynthesisPhotosynthesis

Nutrition in Humans & Other Organisms 

  • In animals, procurement of food is highly variable. The process of nutrition becomes more complex in multicellular organisms as compared to unicellular organisms. In single-celled organisms like Amoeba, the food is taken in through the general body surface.
  • In humans, the digestive system consists of a long alimentary canal and digestive glands. Various parts of the alimentary canal in sequence are the mouth, oesophagus, stomach, small intestine and large intestine.
  • In the mouth, food is crushed by teeth and mixed with saliva, secreted by salivary glands. Saliva contains an enzyme called salivary amylase that breaks down starch into simple sugar.
  • When we swallow the food (bolus), it is further pushed forward by rhythmic contraction and relaxation of muscles present inlining of the alimentary canal. These movements are called peristaltic movements. Thus, the food is carried to the stomach through the food pipe or oesophagus.
  • The stomach is a large C-shaped hollow organ that expands when food enters it. The muscular walls of the stomach help in mixing the food thoroughly, with the gastric secretions.
  • The gastric glands present in the wall of the stomach secrete hydrochloric acid, a protein-digesting enzyme called pepsin and mucus.
  • Hydrochloric acid facilitates the action of the enzyme pepsin as this enzyme works in an acidic medium. Apart from it, hydrochloric acid prevents the fermentation of food and also kills harmful microorganisms present in the food. Mucus protects the inner wall of the stomach from excoriation by highly acidic HCl.
  • From the stomach, the partially digested food (chyme) enters the small intestine. The exit of food from the stomach is regulated by a sphincter muscle which releases it in small amounts into the small intestine.

Digestive SystemDigestive System

  • The length of the small intestine differs in various animals depending on the feeding habit. Herbivores have a longer small intestine (due to the high bulk of vegetal matter and cellulose) as compared to carnivores (due to the smaller bulk of animal food).
  •  The small intestine is the site of the complete digestion of carbohydrates, proteins and fats. The proximal part of the small intestine referred to as the duodenum receives partially digested acidified food from the stomach. Duodenal glands secrete an alkaline mucus-containing juice that helps in neutralising the chyme and protects the duodenal wall from corrosion.

Question for Chapter Notes: Life Processes- 1
Try yourself:Where does the complete digestion of carbohydrates, fats, and protiens takes plaace in a human body?
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  • A common hepatopancreatic duct opens into the duodenum. It is formed of the common bile duct from the liver and gall bladder as well as a pancreatic duct from the pancreas.
  • Fats are present in the form of large globules in the small intestine which makes it difficult for enzymes to act on them. Bile juice from the liver contains bile pigments and bile salts. Bile salts break fats into small globules by a process called emulsification and thus increase the efficiency of enzyme action (lipase).
  • The pancreas secretes slightly alkaline pancreatic juice which contains three major following enzymes:
    (i) Trypsin which digests proteins.
    (ii) Lipase which digests fats.
    (iii) Amylase which digests carbohydrates.
  • The walls of the small intestine contain glands that secrete intestinal juice. The enzymes present in it, finally convert the proteins into amino acids, complex carbohydrates into glucose and fats into fatty acids and glycerol.
  • The inner lining of the small intestine has numerous finger-like projections called villi which increase the surface area for absorption of digested food. The villi are richly supplied with blood vessels that take the absorbed food to every cell of the body, where it is utilised for obtaining energy, building up new tissues and the repair of old ones.

Small IntestineSmall Intestine

  • The undigested food is sent into the large intestine where more water is reabsorbed from undigested food. The rest of the undigested food material is removed from the body via the anus. The exit of this waste material is regulated by the anal sphincter.
  • The food material taken in during the process of nutrition is used by cells to provide energy for various life processes.
  • Some organisms use oxygen to bring about the complete breakdown of glucose in cells into carbon dioxide and water (aerobic respiration).
    Respiration is a biochemical catabolic process that involves:
    (i) Intake of molecular oxygen from the environment
    (ii) Stepwise oxidation of food with incoming oxygen
    (iii) Elimination of carbon dioxide produced during oxidation and
    (iv) Release of energy.

    Question for Chapter Notes: Life Processes- 1
    Try yourself:What is the primary function of villi in the small intestine?
    View Solution
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FAQs on Life Processes- 1 Chapter Notes - Science Class 10

1. What is the process of photosynthesis?
Ans. Photosynthesis is the process by which green plants, algae, and some bacteria convert sunlight, carbon dioxide, and water into glucose and oxygen. This process occurs in the chloroplasts of plant cells, specifically in the chlorophyll pigment. The glucose produced is used as a source of energy for the plant, while the oxygen is released into the atmosphere.
2. How does photosynthesis contribute to the nutrition of plants?
Ans. Photosynthesis is the primary source of nutrition for plants. Through this process, plants produce glucose, which serves as their source of energy for growth, development, and various metabolic activities. Glucose is used to synthesize other organic compounds, such as starch, cellulose, and proteins, which are essential for the plant's structure and function.
3. How does nutrition in humans differ from nutrition in other organisms?
Ans. Nutrition in humans differs from nutrition in other organisms in several ways. Unlike plants, humans are unable to perform photosynthesis and produce their own food. Instead, they rely on consuming other organisms or their products to obtain nutrients. Humans require a balanced diet that includes carbohydrates, proteins, fats, vitamins, and minerals to meet their nutritional needs. Additionally, humans have a more complex digestive system compared to other organisms, allowing for the breakdown and absorption of nutrients.
4. What are the different modes of nutrition in other organisms?
Ans. Other organisms can have different modes of nutrition, depending on their ecological niche and evolutionary adaptations. Some organisms are autotrophs, such as plants and algae, which produce their own food through photosynthesis. Others are heterotrophs, which obtain their nutrition by consuming other organisms or organic matter. Heterotrophs can further be classified into herbivores (eat plants), carnivores (eat other animals), and omnivores (eat both plants and animals). Some organisms, like fungi and bacteria, are decomposers, obtaining their nutrition by breaking down dead organic matter.
5. How does the human digestive system contribute to the process of nutrition?
Ans. The human digestive system plays a vital role in the process of nutrition. It is responsible for breaking down ingested food into smaller molecules that can be absorbed and utilized by the body. The process begins with ingestion, followed by mechanical and chemical digestion in the mouth, stomach, and small intestine. Enzymes and digestive juices help break down carbohydrates, proteins, and fats into simpler forms. The small intestine absorbs the digested nutrients, which are then transported to the bloodstream and delivered to cells throughout the body for energy production and other metabolic processes.
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