CLASS 10 (BIOLOGY NOTES )

                                               LIFE PROCESSES

                                                              CLASS 10

                                                              BIOLOGY

Life Processes are one of the important and major biological functions that help living organisms sustain and reproduce. They include processes like nutrition, respiration, transportation, and excretion.

Nutrition and Respiration

Nutrition is a vital life process through which living organisms obtain and use food for energy, growth, and repair. It is mainly of two types, autotrophic and heterotrophic.

Autotrophic Nutrition occurs in green plants and some bacteria. It helps prepare their own food using sunlight, carbon dioxide, and water through photosynthesis. The presence of chlorophyll enables plants to capture sunlight, converting it into chemical energy in the form of glucose. This process provides energy for all organisms in the food chain.

Heterotrophic Nutrition is seen in animals and humans, where food is obtained from other organisms. It includes:

• Holozoic Nutrition – as in humans and amoeba, involves ingestion, digestion, and absorption.
• Saprophytic Nutrition – in fungi and bacteria, involves feeding on dead and decayed matter.
• Parasitic Nutrition – as in leeches and tapeworms, depends on living hosts for nourishment.

The process of releasing energy in the form of ATP (Adenosine Triphosphate) is called Respiration. It is of two types, aerobic respiration (in the presence of oxygen) and anaerobic respiration (without oxygen). The human respiratory system includes the nasal passage, trachea, bronchi, and alveoli. Gas exchange occurs in alveoli, while inhalation and exhalation help maintain oxygen and carbon dioxide balance.

Photosynthesis

• Photosynthesis is an important process by which food is formed.
• The plants make food using sunlight and water, which provides nourishment to other organisms and themselves.
• Chlorophyll present in the green parts absorbs light energy.
• This light energy is used to split water into hydrogen and oxygen.
• Hydrogen is then used to reduce carbon dioxide into carbohydrates, typically glucose.
• Chlorophyll is essential for photosynthesis and stomata to facilitate the intake of carbon dioxide.

The overall reaction occurring in photosynthesis is as follows:

6CO2 + 6H2O → C6H12O6 + 6O2

Stomata

• Stomata are pores on the leaves that help in the exchange of gases.
• They are mostly found on the underside of the leaf.
• Each stoma is guarded by guard cells, which control the opening and closing of the pore.
• The water content of the guard cells is responsible for their function

Nutrition in Amoeba

• Amoeba feeds by Holozoic mode of nutrition.
• It engulfs the food particle using pseudopodia, the process is called phagocytosis.
• The engulfed food gets enclosed in a food vacuole.
• As the food vacuole passes through the cytoplasm, digestion, absorption, and assimilation, take place.
• When the food vacuole opens outside, the egestion of undigested food takes place.

Nutrition in Humans

• Humans are omnivores, they can eat plant-based food as well as animal-based food.
• Being more complex, humans have a very complicated nutrition system.
• The digestive system has an alimentary canal and associated digestive glands, which together function to nourish the body.
• 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 the alimentary canal, while assimilation of food takes place in the whole body'

Alimentary Canal

• The alimentary canal in humans is a long tube of varying diameter.
• It starts with the mouth and ends with the anus.
• Oesophagus, stomach, small intestine and large intestine are the parts of the alimentary canal.

• Mouth
• • It is the opening of the alimentary canal and helps in the ingestion of food.
  • The buccal cavity, which is present behind the mouth, is also commonly referred to as the mouth.
  • The buccal cavity has teeth and a tongue.
  • The set of teeth helps in the mastication of food.
  • The tongue has taste buds on it and thus helps in tasting the food.
  • The salivary glands also open in the buccal cavity and pour saliva, which initiates the process of digestion.

  Teeth

• Teeth are the hard structures present in the buccal cavity.
• They help us to cut, shear and masticate the food we eat.
• The vertical section of a tooth shows four layers enamel, dentine, cement and dental pulp.
• Enamel is the outermost, shiny, highly mineralized and hardest part of the human body.

• Oesophagus

• The swallowed food passes into the oesophagus.
• It is a muscular tube, about 25 cm long, with a sphincter (valve/opening) at each end.
• Its function is to transport food and fluid, after being swallowed, from the mouth to the stomach.
• Food is pushed down by peristaltic movements.
• STOMACH
• The stomach is a thick-walled bag-like structure.
• It receives food from the oesophagus at one end and opens into the small intestine at the other end.
• The inner lining of the stomach secretes mucous, hydrochloric acid and digestive juices.
• Food is churned into a semi-solid mass in the stomach and is called chyme.
• Enzymes present in gastric juice break down the food.
• Hydrochloric acid helps in the partial digestion of proteins and also kills harmful bacteria.
• The mucus secreted by the wall of the stomach resists the action of HCl on itself

• Small Intestine

  • The small intestine is the longest part of the alimentary canal, about 20 feet long in humans.
  • It has regions, the duodenum, the region which follows the stomach; the jejunum is the middle part; and the ileum is the later region which continues further into the large intestine.
  • The internal surface of the small intestine is folded into finger-like projections called villi.
  • A common pancreatic duct from the pancreas and liver opens into the duodenum.
  • Most of the chemical digestion and absorption takes place in the small intestine.

  Large Intestine

• The large intestine in humans is about 5 feet long.
• It has two regions, the colon ( about 1.5 m) and the rectum (10 cm in length in the adult).
• The region of the large intestine after the ileum is called the colon, while the last part is called the rectum.
• Colon has three regions, ascending colon, transverse colon and descending colon.
• At the base of the ascending colon, a small finger-like out-growth is seen and is called an appendix.
• It houses many useful bacteria required for the digestion of food.
• Rectum opens to the outside by the anus.
• The anus has internal and external anal sphincters.

• Digestive Juices

• Pancreatic juice, bile and intestinal juice (succus entericus) are collectively called digestive juices.
• A common duct from digestive glands pours the secretions into the duodenum.
• Chyme enters the small intestine, where complete digestion takes place due to the action of various enzymes.
• In the duodenum, the acidity of chyme is turned to alkalinity by the action of bile coming from the liver. This is necessary for pancreatic enzyme action.
• Bile also emulsifies the fats into smaller globules.
• Pancreatic and intestinal amylases break down carbohydrates into glucose.
• Trypsin and chymotrypsin are the proteases responsible for the breakdown of proteins finally into amino acids.
• Lipase is the enzyme which acts on the emulsified fats and breaks them down into glycerol and fatty acids.
• 
  
  
  
  

Respiration

Introduction to Respiration

• Respiration broadly means the exchange of gases.
• Animals and plants have different means of exchange of gases.
• At a cellular level, respiration means the burning of food to generate the energy needed for other life processes.
• Cellular respiration may take place in the presence or absence of oxygen.

Respiratory System

• The human respiratory system involves the nose, nasal cavities, pharynx, larynx, trachea/windpipe, bronchi, bronchioles and alveoli.
• Bronchioles and alveoli are enclosed in a pair of lungs.
• The rib cage, muscles associated with the rib cage and diaphragm all help in the inhalation and exhalation of gases.
• The exchange of gases takes place between an alveolar surface and surrounding blood vessels.
• Alveoli provide a large surface area for the exchange of gases.

Inhalation and Exhalation

• The process of taking in air rich in oxygen is called inhalation.
• Similarly, the process of giving out air rich in carbon dioxide is called exhalation.
• One breath comprises one inhalation and one exhalation.
• A person breathes several times a day.
• The number of times a person breathes in one minute is termed as his/her breathing rate.

Respiration in Plants

• Unlike animals and humans, plants do not have any specialized structures for gaseous exchange.
• They have stomata (present in leaves) and lenticels (present in stems), which are involved in the exchange of gases.
• Compared to animals, plant roots, stems, and leaves respire at a very lower rate.

• Transpiration is a biological process in which water is lost in the form of water vapour from the aerial parts of the plants.
• This process occurs mainly through the stomata, where the exchange of gases (oxygen and carbon dioxide) occurs.
• Transpiration helps in the transportation of water from roots to the upper parts of plants, and this is explained by the ‘transpirational pull theory’.
• Loss of water, especially from leaves, acts as a straw effect and pulls water upwards from roots.

Transportation in Human Beings

Transportation

• All living organisms need a few necessary components like air, water, and food for their survival.
• On a regular basis, animals ensure these elements by breathing, drinking and eating.
• The required elements are transported to their body cells and tissues by a  transportation system.
• In plants, the vascular tissue is responsible for transporting the substances.

Transportation in Humans

• Transportation in humans is done by the circulatory system.
• The circulatory system in humans mainly consists of blood, blood vessels and the heart.
• It is responsible for the supply of oxygen and nutrients and the removal of carbon dioxide and other excretory products.
• It also helps to fight infections.

 Heart

• The muscular organ which is located near the chest, slightly towards the left in the thoracic region.
• The heart is the main pumping organ of the body.
• The human heart is divided into four chambers which are involved in the transportation of oxygenated and deoxygenated blood.
• The upper two chambers are called atria, whereas the lower two chambers are called ventricles.

Double Circulation

• In the human body, blood circulates through the heart twice.
• Once it goes through the heart during pulmonary circulation and a second time during systemic circulation.
• Hence, circulation in human beings is called double circulation.

Transportation in Plants

Transportation in Plants

• Transportation is a vital process in plants.
• The process involves the transportation of water and necessary nutrients to all parts of the plant for its survival.
• Food and water transportation takes place separately in plants.
• Xylem transports water, and phloem transports food.

Translocation

• The transport of food in the plant through phloem via a process such as mass flow is called translocation.
• Photosynthates, i.e. sugars and organic molecules such as amino acids, organic acids, proteins and inorganic solutes like potassium, magnesium, nitrate, calcium, sulfur and iron from source tissues (mature leaves) to the sink cells (areas of growth and storage) are transported through the phloem.
• Material like sucrose is loaded from leaves to phloem using the energy of ATP.
• Such a transfer increases the osmotic pressure causing the movement of water from nearby cells into phloem tissue, and the material gets transported through the phloem.

Excretory System of Humans

• The excretory system in humans includes
  • a pair of kidneys,
  • a pair of ureters,
  • a urinary bladder and
  • urethra.
• It produces urine as a waste product.

  Kidneys

• Paired kidneys are the main excretory organs of the body.
• They are basically the filtration units of the human body.
• Each kidney is made up of many tiny filtration units called nephrons.
• perform crucial functions like:
1. Filtering waste materials, medications, and toxic substances from the blood.
2. Regulation of osmolarity, i.e. the fluid balance of the body.
3. Regulation of ion concentration in the body.
4. Regulation of pH.
5. Regulation of extracellular fluid volume.
6. Secreting hormones that help produce red blood cells promotes bone health and regulates blood pressure.
• Hemodialysis
• When the kidneys fail, it results in a lot of complications, and to compensate for this situation, a technology called dialysis has been developed.
• It uses a machine filter called a dialyzer or artificial kidney.
• This is to remove excess water and salt, balance other electrolytes in the body and remove waste products of metabolism.
• Blood from the body is removed and flows through a series of tubes made up of a semipermeable membrane.
• A dialysate flows on the other side of the membrane, which draws impurities through the membrane.

• Excretion in Plants

  • Cellular respiration, photosynthesis, and other metabolic reactions produce a lot of excretory products in plants.
  • Carbon dioxide, excess water produced during respiration and nitrogenous compounds produced during protein metabolism are the major excretory products in plants.
  • Plants produce two gaseous waste products, i.e. oxygen during photosynthesis and carbon dioxide during respiration.
  • The excretion of gaseous waste in plants takes place through stomatal pores on leaves.
  • Oxygen released during photosynthesis is used for respiration, while carbon dioxide released during respiration is used for photosynthesis.
  • Excess water is excreted by transpiration.
  • Organic by-products generated by the plant are stored in different forms in different parts.
  • The gums, oils, latex, resins, etc., are some waste products stored in plant parts like bark, stems, leaves, etc.
  • Eventually, plants shed off these parts.