Life Processes NCERT Notes Class 10th

 Chapter: Life Processes.

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

 

Life Processes:

·        Maintenance of living organisms is essential even if they are moving, resting or even sleeping Since these maintenance processes are needed to prevent damage and breakdown energy is needed for them. This energy comes outside the body of the individual organism.

·        The processes which together perform the function of maintenance of life are called as life processes."

·        Nutrition, respiration, circulation, excretion are examples of essential life processes.

·        In unicellular organisms, all these processes are carried out by that single cell.

·        In multicellular organisms, well-developed systems are present to carry out the processes.

 

Nutrition:

The process of acquiring food that is needed for nourishment and sustenance of the organism is called nutrition.

·        There are two main modes of nutrition, autotrophic and heterotrophic.

·        Heterotrophic nutrition has subtypes: holozoic, parasitic and saprophytic nutrition.

 

 

How do living things get their food?

·        Some organisms use simple food material obtained from inorganic sources in the form of carbon dioxide and water.

·        Autotrophs include green plants and some bacteria.

·        Other organisms utilize complex substances.

·        To achieve this, organisms use bio-catalysts called enzymes.

·        The heterotrophs survival depends directly or indirectly on autotrophs.

·        Heterotrophic organisms include animals and fungi.

 

Autotrophic Nutrition:

If an organism can nourish itself by making its own food using sunlight or chemicals, such mode of nutrition is called as Autotrophic Nutrition.

                    i.        Plants photosynthesis (use of light energy) and are called photoautotrophs.

                   ii.        Few bacteria use chemicals to derive energy and are called chemoautotrophs.

 

Photosynthesis:

·        Photosynthesis is an important process by which food is formed.

·        Carben and energy requirements of autotrophs are fulfilled.

·        Autotrophs take in substance from outside and convert into stored forms of energy.

·        Chlorophyll is present in the green parts absorbs light energy.

·        This light energy is used to split water into H₂ and O₂.

·        Carbohydrates are utilized to provide energy to the plant.

·        Chlorophyll is essential for photosynthesis and stomata to facilitate intake of carbon dioxide.

 

6C0₂+12H₂O Chlorophyll sunlight → C₆H₁₂O₆ + 602 + 6H20. (glucose).

 

Raw Materials for Photosynthesis: CO₂ and H₂O.

Site of Photosynthesis: Chloroplast, in the leaf. Chloroplast contain chlorophyll.

 

Stomata:

·        Tiny pores present on the surface of leaves.

·        It helps in the exchange of gases O2 & CO2.

·       
Losses large amount of water during transpiration and helps in up flow of water.

 

Chloroplast.

It contains the green pigment chlorophyll which has a pivotal role in photosynthesis.

 

Heterotrophic Nutrition: There is a range of strategies by which the food is taken in and used by the organisms. Some organisms break down the food materials outside the body and absorb it.

Holozoic Nutrition: Animals take in solid food and break-down it inside the body. e.g.  Amoeba, animals.

Saprophytic Nutrition: Organisms fed on dead and decaying organic matter. e.g. Fungi and other saprophytes. The food is partially digested outside the body and then it is absorbed.

Parasitic Nutrition: Parasites live inside or outside other organisms (host) and derive nutrition from it. E.g. Leech, Ascaris and Cucuta.

Nutrition in Amoeba: Amoeba feeds by holozoic mode of nutrition. It engulfs the food particles using pseudopodia, the process called phagocytosis. The engulfed food gets enclosed. Food vacuole is formed. Undigested food is thrown out.

 

Nutrition in Human Beings:

The digestive system comprises of alimentary canal and associated digestive glands.

·        There are five stages in human nutrition: Ingestion, Digestion, Absorption, Assimilation and Egestion.

·        Four stages i.e., ingestion, digestion, absorption and egestion take place in alimentary canal, while assimilation of food takes place in the whole body.

 

Human Digestive System:

Mouth: It is the opening of the alimentary canal and helps in ingestion of food. Buccal cavity is present behind the mouth and has teeth and tongue.

Salivary Glands - secrete saliva (Salivary Amylasa).

Teeth Chewing and Grinding of food.

Tongue Rolling and Tasting of food.

 

Esophagus: The swallowed food passes into the esophagus. It is a muscular tube, about 25 cm long with a sphincter (valve /opening) at each end. Takes food from mouth by peristatic movement. Function is: contraction and expansion of alimentary canal.

 

Stomach: It is a thick-walled bag like structure. It receives food from esophagus at one end and opens into the Small intestine at other end.

Gastric Juices

Pepsin                                                   HCL                                                       Mucus

breaks down protein                       Makes medium acidic                 Protects inner lining of stomach

 

Small Intestine: It is the longest part of the alimentary Canal, about 20 feet long. It has three regions: duodenum, jejunum and ileum. Internal surface of small intestine is folded into finger like projections called villi.

Liver secretes: bile

Pancreases Secrete: pancreatic juice

 

Intestinal Enzyme

Carbohydrates                                         Fats                                             Protien

Glucose                                        Fatty acid + Glycerl                                  Amino acid.

 

Pancreatic Juice

Trypsin                                                                                          Lipase

Proteins - Peptones                                                                          Emulsified Fats Fatty acid

  Glycerol

Large Fat globules               >        Bile Juice        >        Small fat globules.

 

Large Intestine: The region of large intestine after ilium is called the large intestine, The large intestine is about 5 feet long in humans. It absorbs excess of water.

Rectum: Temporary collection of waste. It opens to outside the anus.

Anus: The anus has internal and external anal Sphinchters. Helps in egestion.

 

 

Respiration: Respiration broadly means the exchange of gases, typically the intake of oxygen and release of carbon dioxide from oxidation of complex organic substance.

(i) Gaseous Exchange: Intake of oxygen from atmosphere and release of carbon dioxide.

 

Respiration

Aerobic                                                                                                   Anaerobic.

In the presence of Oxygen.                                                               In the absence of oxygen

Occurs is mitochondria                                                                     occurs in cytoplasm.     

End products are Co2 and H2O                                                          end products alcohol

More amount of energy released (38 ATP).                      less amount of energy released (2 ATP)

 

 

 

 

Human Respiratory system:

Passage of air through respiratory system.

Nostril > Nasal Passage > Nasal Cavity > Pharynx > Larynx > Trachea > Bronchi > Lungs > Bronchioles > Alveolar sac > Blood Capillaries.

 

Mechanism of Breathing:

Breathing

Inhalation                                                                   Exhalation      

1. During inhalation thoracic cavity expands.                    1. Thoracic cavity contracts

2. Ribs lift up                                                              2. Ribs move downwards.

3. Diaphragm becomes flat                                            3. Diaphragms becomes dome shaped

4. Volume of lungs increases and air enters the lungs. 4. Volume of lungs decrease and air exits from lungs.

 

Exchange of Gases between alveolus, blood and tissues:

1. Air (rich in O₂) (in alveolus) > Blood (through blood vessels) (capillaries) > O₂ Binds with Hemoglobin in RBC > O₂ is released is tissue

2. CO₂ (From tissue) > CO₂ (released into blood) > CO₂ (dissolved in blood) > Blood vessels (capillaries) (in alveoli) > CO2 (released in alveolar sac) > CO₂ sent out through nostrils.

 

Terrestrial Organism: Use atmospheric oxygen for respiration.

Aquatic Organism: Use oxygen dissolved in water.

Respiration in Plants: Respiration in plants is similar thar the respiration in animals. Gaseous exchange occurs through:

(1) Stomata in leaves

(2) Lenticles in stems

(3) General surface of roots.

Diffusion: Diffusion is the movement of molecules from high concentration area to the low concentration area without any energy.

Cellular Respiration: Set of metabiotic reactions occurring inside the cells to convert biochemical energy obtained from food into a compound called Adenosine triphosphate (ATP).

Catabolism: process of breaking molecules into energy.

Anabolism: process of synthesizing all compounds required by the cells.

 

Transportation: Human beings like other multicellular organism need regular supply of food, oxygen etc. This function is performed by circulatory system or Transport System.

 

Circulatory system of human beings consists of:

 

A pumping organ - Heart > Blood Vessels - Arteries & Veins > Circulatory medium - Blood & Lymph.

 

Deoxygenated blood (from body) > Vena Cava > Right Atrium > Right Ventricle > Lungs > Oxygenated blood > Left Atrium > left ventricle > AORTA > Body Parts. ::Blood Circulation in Human Heart.::

 

 

Heart: It is a muscular organ located near chest slightly towards the left in thoracic cavity. Heart is main pumping Organ of the body. It has two cupper chambers called atria and lover two chambers called ventricles.

Double Circulation: Blood travels twice through the heart in one complete cycle of body.

Pulmonary Circulation: Blood moves from heart to the lungs and lack the heart.

Systemic Circulation: Blood moves from heart to rest of the leady and back to the heart.

Sectional view of Human Heart.

Blood

Solid Components                                                                                      Liquid Component.

Blood Corpuscles                                                                                                  Plasma.

RBCS   Platelets WBCS

 

RBCs: Carries respiratory gases (O₂, CO₂).

Contains Hemoglobin

Impart red color to the blood.

Platelets: Helps in blood Clotting.

WBCs: Provide Body defense by engulfing the germs and producing antibodies.

Lymph: yellowish fluid that escapes from wood capillaries into the intercellular spaces. Lymph flows from the tissue to the heart assisting in transportation and destroying germs.

 

Blood Vessels

Arteries                                                                                                                        Viens

 

Arteries:

1. Carry Oxygenated blood from heart

2. Also called distributing vessels.

3. Thick and elastic

4. Valves absent.

5. Deep scaled.

Veins:

1. Carry deoxygenated blood from body parts

2. Also called collecting vessels.

3. Thin and less elastic.

4. Values present to prevent back flow of blood.

5. superficial

 

Transportation in Plants: Two type of conducting tissue:

Xylem: Carries water & minerals from the roots to other part of the plant. No energy used.

Phloem: Carries product of photosynthesis from leaves. Energy is used from ATP.

Transpiration is the process by which plant lose water in the form of water vapors. Helps in temperature regulation in plants.

Translocation: Transport of food from leaves to different part of the plant is called Translocation.

Excretion in Humans: The process of removal of harmful wastes from the body is called excretion.

Excretory system in Human beings.

Excretory system consists of:

·        A pair of Kidney

·        A urinary bladder

·        A pair of Ureter

·        A Urethra.

 

Process of Excretion: Renal artery brings in blood containing waste substances to the Kidneys. Kidney filters blood. Urine produced in kidney passes through the ureters into the urinary bladder until it is released through the urethra.

 

Functions of kidney: It removes waste product from blood, area which is produced in lever.

Nephron: Each Kidney has a large number of filtrate units called nephrons. Nephron is a structural and functional unit of kidney.

 

Mechanism of Urine Formation:

·        Glomerular Filtration

·        Tubular re-absorption

·        Secretion

 

Hemodialysis: The process of purifying blood by an artificial Kidney. Meant for kidney failure patients.

Excretion in Plants:

1. Oxygen released during photosynthesis

2. H₂O by transpiration

3. Waste may be stored in leaves, bark etc.

4. Waste products stored as gums, resins in old xylem.

5. Plants excrete some waste into the soil around them.