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An organism can live provided it gets proper nutrients and energy, its body is able to process nutrients into food, the organism is able to reproduce to give birth to young, and is capable of removing waste from its body.

Life processes are processes essential for the survival of an organism that includes nutrition, respiration, transportation, excretion, movement, and reproduction.
 

Nutrition:

Nutrition is the process of acquiring food that is required for nourishment and growth.

Humans, animals, and plants all depend on plants for food, nutrition and also for oxygen. The plants, in turn, depend on soil, water, air and sunlight to grow and thrive. A healthy soil provides a proper combination of minerals and nutrients called mineral nutrition for a plant to grow.

Did you know that certain plants can be grown in a solution of fertilisers and minerals in the absence of soil? This technique is called Hydroponics. Another technique called Aquaponics actually uses water infused with natural fertilisers from fish to directly grow plants in water.

Nutrition:

Nutrition Is the process of intake of food which is used to generate energy. The two different types of nutrition are: 

• Autotrophic Nutrition: Defined as a mode of nutrition in which organisms synthesise their own food. Example: Plants and green algae.

• Heterotrophic Nutrition: Defined as a mode of nutrition in which organisms depend on other living organisms for their food. Example: Humans and animals..

Photosynthesis:

• Plants are capable of synthesising their own food by a process known as photosynthesis. The process takes place in chlorophyll, a pigment present in the chloroplast (double-membrane organelle).
• Plants require carbon dioxide, water, and sunlight for this life process.
• Below is the equation for photosynthesis:

6CO₂ +12H₂ O→C₆H₁₂O₆ +6O₂ +6H₂ O
 

The two main steps of photosynthesis are:

1. Light reaction of photosynthesis: Absorption of sunlight by chlorophyll which induces splitting of water molecules. 
2. Dark reaction of photosynthesis: Hydrogen produced is used for the synthesis of carbohydrates which are stored as starch in the leaves. 
    
3.  
   2. Nutrition in Animals

   Animals use the heterotrophic nutrition process where organisms depend on other living organisms for their food. For example, plants and animals are the primary sources of food and nutrition for humans.

   There are two types of heterotrophic nutrition processes, saprophytic and holozoic.

   • Saprophytic nutrition: In this type of nutrition, organisms secrete digestive enzymes or juices and subsequently ingest this partially digested food. Fungi and other lower organisms are saprophytes.
   • Holozoic nutrition: In this type of nutrition, the complete process of nutrition takes place inside the body as in the case of humans. This process occurs in five steps namely:

   1. Ingestion (process of intake of food)
   2. Digestion (breakdown of food into simpler substances to obtain energy)
   3. Absorption (digested food/simpler substances are absorbed)
   4. Assimilation (the process of using the energy obtained to perform life processes)
   5. Egestion (the process of removing undigested food)
   6. 3. Respiration in Plants and Animals

   7. Humans and other organisms require oxygen to perform metabolic processes to sustain life. Plants are the primary source of oxygen on earth. The process of respiration involves inhaling oxygen, passing oxygen to the blood vessels through lungs, and exhaling carbon dioxide in the reverse process. This microscopic gas exchange occurs rapidly, with oxygen being taken into the body while carbon dioxide is removed.

      In this topic, you will learn about aerobic and anaerobic respiration, the process of respiration in plants and animals, and the mechanism of breathing in humans.

      

       

      4. Transportation in Animals

      For any organism to thrive and function, vital substances such as water, nutrients, oxygen, carbon dioxide, hormones, waste etc. need to travel and reach the right organs within the organism. Organisms while absorbing nutrients also need to remove waste from their bodies. These internal transport systems differ from simple cell organisms to large multicellular organisms, from plants to animals.

      In simple cell organisms, substances pass from one cell to another using the process of diffusion.

      In larger, multicellular organisms, substances need to travel longer distances as well as reach organs that might be large and thick.  Hence transportation occurs via a ‘circulatory system’ that includes the heart, blood vessels, and blood that distribute, deliver and collect various substances throughout the body.

      The circulatory system, also called the cardiovascular system or the vascular system, is an organ system that permits blood to circulate and transport nutrients to and from the cells in the body. This helps in providing nourishment, immunity to fight infections and disease, maintain homoeostasis and stabilise body temperature and pH.

      The circulatory system is often described as containing two separate systems, cardiovascular system and the lymphatic system.

      Cardiovascular System: distributes blood comprising the heart, blood and blood vessels.

      • The circulatory system consists of the heart (organ), vessels (arteries, veins, and capillaries) and blood (connective tissue).
      • The major differences between arteries and veins are that arteries carry oxygenated blood, contain thick elastic walls and do not contain valves, unlike veins. Arteries branch out to form the smallest of blood vessels called capillaries. These capillaries then merge and go on to form veins.
      • Blood vessels carry blood, a connective tissue that contains red blood cells (RBC), white blood cells (WBC) and platelets. Blood is circulated by the heart, through the vertebrate vascular system, carrying oxygen and nutrients to and waste materials away from all body tissues.
      • The cardiovascular system differs from one vertebrate family to the other:
        • Fishes are characterised by two-chambered hearts.
        • Amphibians and reptiles contain three-chambered hearts that allow for mixing of oxygenated and deoxygenated blood.
        • Birds and mammals are characterised by the presence of four-chambered hearts.

      Mechanism of Circulation in Human Beings:

      All veins → Right atrium → Right ventricle → Pulmonary artery → lungs → Oxygenation occurs → pulmonary vein collects oxygenated blood → Left atrium (Relaxed state) → Atrium contracts → Left ventricle expands, receives blood → Ventricle contracts → blood sent to aorta → All parts of the body

      Lymphatic system: Circulates lymph and is made of lymph nodes and lymph vessels.

      Lymph:

      • Is also known as interstitial fluid and is colourless but similar in composition to blood but with less protein.
      • Is recycled excess blood plasma after it has been filtered from the interstitial fluid (between cells) and returned to the lymphatic system.
      • Carries digested and absorbed fat from the intestine.
      • Is formed when plasma proteins and some blood cells diffuse from capillaries into tissue spaces.

      The flow of Lymph:

      Lymph → Lymphatic capillaries from inter-cellular spaces → Large lymph vessels (tonsils, groin, armpits) → Large veins

      

       

       

      5. Transportation in Plants

      Plants have simpler physiological structures and require less food and water to survive when compared to animals. Therefore plants use a simpler and a slower transport system as they do not move much. Plants obtain,

      • water, minerals, and nutrients (from fertilisers) from the soil via the roots, and
      • moisture, carbon dioxide and oxygen from the leaves.

      These substances are circulated across all parts of the plant using the transportation method. The transport system in plants consists of tube-like passages made up of vascular tissue called xylem and phloem.

      Unlike humans, who have a complex circulatory system consisting of a pumping organ like heart, blood vessels and lymph, the transport system in plants is relatively simple. It consists of the xylem and phloem tissues that are responsible for the transport of water and nutrients respectively.

      Xylem 
      The vascular tissue is shaped like a duct and transports mainly water from the roots to shoots and leaves in an upward movement. Individual vessels connect to each other forming a continuous network that transport water. Xylem transports a small amount of nutrients as well.

      Phloem
      While water and nutrients are transported by the xylem from the roots to the very tips of the plant, another system is used to transport synthesised food from the leaves to different parts of the plant. This process is called translocation and is carried out by the phloem.
      Phloem is set of cells that control the movement of food in the form of sugars, from the leaves to different parts of the plant. The phloem is positioned just outside the xylem and uses water as a medium of transportation.