Class 10 Biology Chapter 1 Notes PDF Download
Biology is a fascinating subject that deals with the study of life and living organisms. It covers various topics such as structure, function, growth, evolution, distribution, and classification of living things. In this article, we will provide you with the notes for class 10 biology chapter 1, which is about life processes. Life processes are the basic functions that are essential for the survival of living organisms. These include nutrition, respiration, transportation, and excretion. We will also provide you with the diagrams, keywords, and important questions related to this chapter. You can download the PDF version of these notes from the link given at the end of this article.
class 10 biology chapter 1 notes pdf download
Introduction
Life is a complex phenomenon that involves various physical and chemical processes. These processes enable living organisms to obtain energy, grow, develop, reproduce, respond to stimuli, and maintain homeostasis. Homeostasis is the ability of an organism to maintain a stable internal environment despite the changes in the external environment. The processes that help in maintaining homeostasis are called life processes.
What are life processes?
Life processes are the vital activities that are performed by living organisms to sustain life. These include:
Nutrition: It is the process of obtaining food and using it for energy, growth, repair, and maintenance.
Respiration: It is the process of breaking down food molecules to release energy.
Transportation: It is the process of moving substances from one part of the body to another.
Excretion: It is the process of removing waste products from the body.
These life processes are common to all living organisms, but they may differ in their mode and complexity depending on the type and level of organization of the organism.
Types of nutrition
Nutrition is the process by which living organisms obtain food and use it for various purposes. Food is a source of energy and raw materials for the synthesis of new molecules. There are two types of nutrition: autotrophic nutrition and heterotrophic nutrition.
Autotrophic nutrition
Autotrophic nutrition is the mode of nutrition in which organisms make their own food from simple inorganic substances like carbon dioxide and water. Autotrophs are also called producers because they produce organic matter from inorganic matter. The most common example of autotrophs are green plants, which use light energy to synthesize food by a process called photosynthesis. Photosynthesis is a biochemical process that converts light energy into chemical energy stored in glucose molecules. The equation for photosynthesis is:
C6H12O6 + 6O2">
In this equation, CO2 stands for carbon dioxide, H2O stands for water, C6H12O6 stands for glucose, and O2 stands for oxygen.
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Heterotrophic nutrition
Heterotrophic nutrition is the mode of nutrition in which organisms obtain food from other organisms or organic sources. Heterotrophs are also called consumers because they consume organic matter produced by autotrophs or other heterotrophs. The most common examples of heterotrophs are animals, fungi, bacteria, etc. There are different types of heterotrophic nutrition, such as: - Holozoic nutrition: It is the type of nutrition in which organisms ingest solid or liquid food and digest it inside their body. For example, humans, dogs, cats, etc. - Saprophytic nutrition: It is the type of nutrition in which organisms feed on dead and decaying organic matter. For example, fungi, bacteria, etc. - Parasitic nutrition: It is the type of nutrition in which organisms live on or inside another living organism (host) and derive nourishment from it. For example, tapeworms, lice, etc. - Symbiotic nutrition: It is the type of nutrition in which two organisms live together and benefit from each other. For example, lichens, which are composed of algae and fungi. Nutrition in human beings
Human beings are holozoic heterotrophs, which means they ingest solid or liquid food and digest it inside their body. The process of digestion involves the following steps:
- Ingestion: It is the intake of food through the mouth. - Digestion: It is the breakdown of complex food molecules into simpler ones by mechanical and chemical means. - Absorption: It is the passage of digested food from the digestive tract into the blood or lymph. - Assimilation: It is the utilization of absorbed food for various purposes like energy, growth, repair, etc. - Egestion: It is the elimination of undigested food and other waste products from the body. The digestive system of human beings consists of the following parts:
Digestive system and its parts
The digestive system of human beings consists of the following parts:
- Alimentary canal: It is a long tube that extends from the mouth to the anus. It has different regions such as mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, and anus. - Accessory organs: These are the organs that help in digestion but are not part of the alimentary canal. They include salivary glands, liver, gall bladder, and pancreas. The diagram below shows the digestive system of human beings:
Digestion process and enzymes
The digestion process and enzymes involved in different parts of the digestive system are as follows:
- Mouth: The mouth is the opening through which food enters the body. The teeth help in chewing the food into smaller pieces. The tongue helps in mixing the food with saliva. Saliva is a watery fluid secreted by the salivary glands. It contains an enzyme called salivary amylase or ptyalin, which breaks down starch into maltose. The food is then swallowed and passes through the pharynx and esophagus to reach the stomach. - Stomach: The stomach is a muscular sac that stores and churns the food. It secretes gastric juice, which contains hydrochloric acid and enzymes like pepsin and rennin. Pepsin breaks down proteins into peptides. Rennin helps in coagulating milk proteins. The food is partially digested in the stomach and forms a semi-solid mass called chyme. - Small intestine: The small intestine is a long coiled tube that receives chyme from the stomach and bile from the liver and gall bladder. Bile is a greenish-yellow fluid that helps in emulsifying fats. The small intestine also receives pancreatic juice from the pancreas. Pancreatic juice contains enzymes like pancreatic amylase, trypsin, lipase, and nuclease. Pancreatic amylase breaks down starch into maltose. Trypsin breaks down peptides into amino acids. Lipase breaks down fats into fatty acids and glycerol. Nuclease breaks down nucleic acids into nucleotides. The small intestine also secretes intestinal juice, which contains enzymes like maltase, sucrase, lactase, peptidase, and nucleosidase. Maltase breaks down maltose into glucose. Sucrase breaks down sucrose into glucose and fructose. Lactase breaks down lactose into glucose and galactose. Peptidase breaks down peptides into amino acids. Nucleosidase breaks down nucleotides into nitrogenous bases and sugars. The digested food is then absorbed by the villi and microvilli present on the inner wall of the small intestine. - Large intestine: The large intestine is a wider tube that receives undigested food from the small intestine. It absorbs water and some minerals from it and forms feces or stools. The feces are stored in the rectum until they are expelled through the anus. Respiration
Respiration is the process of releasing energy from food molecules by breaking them down in the presence of oxygen. Respiration is essential for living organisms because it provides them with the energy they need to perform various functions. Respiration can be of two types: aerobic respiration and anaerobic respiration.
Types of respiration
Aerobic respiration is the type of respiration that occurs in the presence of oxygen. It is the most efficient way of releasing energy from food molecules. The equation for aerobic respiration is:
6CO2 + 6H2O + energy">
In this equation, C6H12O6 stands for glucose, O2 stands for oxygen, CO2 stands for carbon dioxide, H2O stands for water, and energy stands for ATP.
Anaerobic respiration is the type of respiration that occurs in the absence of oxygen. It is a less efficient way of releasing energy from food molecules. The equation for anaerobic respiration in animals is:
2C3H6O3 + energy">
In this equation, C6H12O6 stands for glucose, C3H6O3 stands for lactic acid, and energy stands for ATP.
The equation for anaerobic respiration in plants and some microorganisms is:
2C2H5OH + 2CO2 + energy">
In this equation, C6H12O6 stands for glucose, C2H5OH stands for ethanol, CO2 stands for carbon dioxide, and energy stands for ATP.
Respiratory system and its parts
The respiratory system of human beings consists of the following parts:
- Nasal cavity: It is the opening through which air enters the body. It filters, moistens, and warms the air before it reaches the lungs. - Pharynx: It is a common passage for both air and food. It connects the nasal cavity and the mouth to the larynx and the esophagus. - Larynx: It is also called the voice box. It contains vocal cords that produce sound when air passes through them. - Trachea: It is also called the windpipe. It is a tube that carries air from the larynx to the bronchi. - Bronchi: They are two branches of the trachea that enter the lungs. They further divide into smaller tubes called bronchioles. - Bronchioles: They are the smallest tubes in the respiratory system. They end in tiny sacs called alveoli. - Alveoli: They are the functional units of respiration. They are surrounded by a network of capillaries that exchange gases with them. The diagram below shows the respiratory system of human beings:
Respiratory process and gas exchange
The respiratory process and gas exchange involved in different parts of the respiratory system are as follows:
- Inhalation: It is the process of taking in air through the nose or mouth into the lungs. The diaphragm and the intercostal muscles contract to create a low pressure in the chest cavity. This causes the air to rush into the lungs. - Exhalation: It is the process of expelling air from the lungs through the nose or mouth. The diaphragm and the intercostal muscles relax to create a high pressure in the chest cavity. This causes the air to move out of the lungs. - Gas exchange: It is the process of exchanging oxygen and carbon dioxide between the alveoli and the capillaries. The alveoli have a thin wall that allows the diffusion of gases. Oxygen diffuses from the alveoli into the blood, while carbon dioxide diffuses from the blood into the alveoli. The oxygenated blood is then carried by the pulmonary veins to the heart, while the deoxygenated blood is carried by the pulmonary arteries to the lungs. Transportation in plants
Transportation in plants is the process of moving water, minerals, and food from one part of the plant to another. Plants have two types of tissues that help in transportation: xylem and phloem.
Xylem and phloem
Xylem is a vascular tissue that transports water and minerals from the roots to the leaves. It consists of dead cells that form long tubes called vessels and tracheids. Xylem also provides mechanical support to the plant.
Phloem is a vascular tissue that transports food from the leaves to other parts of the plant. It consists of living cells that form long tubes called sieve tubes and companion cells. Phloem also helps in distributing hormones and other substances within the plant.
The diagram below shows the xylem and phloem in a plant:
Transpiration and translocation
Transpiration is the process of loss of water from the aerial parts of the plant, mainly through the stomata. Stomata are tiny pores present on the surface of the leaves that allow gas exchange. Transpiration helps in cooling the plant, creating a suction force for water uptake, and maintaining turgor pressure.
Translocation is the process of movement of food from the leaves to other parts of the plant through the phloem. Translocation is driven by a pressure gradient created by osmosis and active transport.
Transportation in animals
Transportation in animals is the process of moving substances like oxygen, carbon dioxide, nutrients, hormones, etc. from one part of the body to another. Animals have a circulatory system that helps in transportation. The circulatory system consists of three components: blood, blood vessels, and heart.
Circulatory system and its parts
The circulatory system and its parts are as follows:
- Blood: Blood is a fluid connective tissue that carries various substances throughout the body. It consists of two components: plasma and blood cells. Plasma is the liquid part of blood that contains water, salts, proteins, hormones, etc. Blood cells are the solid part of blood that include red blood cells, white blood cells, and platelets. Red blood cells carry oxygen and carbon dioxide using a pigment called hemoglobin. White blood cells fight against infections and foreign particles using antibodies and phagocytosis. Platelets help in blood clotting and wound healing. - Blood vessels: Blood vessels are tubular structures that carry blood throughout the body. There are three types of blood vessels: arteries, veins, and capillaries. Arteries carry oxygenated blood from the heart to different parts of the body. They have thick and elastic walls that withstand high pressure. Veins carry deoxygenated blood from different parts of the body to the heart. They have thin and less elastic walls that have valves to prevent backflow of blood. Capillaries are the smallest and thinnest blood vessels that connect arteries and veins. They exchange substances with the tissues through their permeable walls. - Heart: Heart is a muscular organ that pumps blood throughout the body. It is located in the chest cavity between the lungs. It has four chambers: two atria and two ventricles. The atria receive blood from the veins, while the ventricles pump blood into the arteries. The heart beats rhythmically due to the presence of a pacemaker called the sinoatrial node. The heart rate is controlled by the nervous system and hormones. The diagram below shows the circulatory system of human beings:
Blood and its components
Blood is a fluid connective tissue that carries various substances throughout the body. It consists of two components: plasma and blood cells. Plasma is the liquid part of blood that contains water, salts, proteins, hormones, etc. Blood cells are the solid part of blood that include red blood cells, white blood cells, and platelets. Red blood cells carry oxygen and carbon dioxide using a pigment called hemoglobin. White blood cells fight against infections and foreign particles using antibodies and phagocytosis. Platelets help in blood clotting and wound healing.
The table below shows the functions and characteristics of blood and its components:
Component Function Characteristic --- --- --- Blood Transports oxygen, carbon dioxide, nutrients, hormones, etc. Reddish fluid that makes up about 8% of body weight Plasma Provides medium for transport and maintains osmotic pressure Yellowish fluid that makes up about 55% of blood volume Red blood cells Carry oxygen and carbon dioxide using hemoglobin Biconcave discs that lack nucleus and organelles White blood cells Fight against infections and foreign particles using antibodies and phagocytosis Irregular shaped cells that have nucleus and organelles Platelets Help in blood clotting and wound healing Fragments of cells that lack nucleus Blood vessels and blood pressure
Blood vessels are tubular structures that carry blood throughout the body. There are three types of blood vessels: arteries, veins, and capillaries. Arteries carry oxygenated blood from the heart to different parts of the body. They have thick and elastic walls that withstand high pressure. Veins carry deoxygenated blood from different parts of the body to the heart. They have thin and less elastic walls that have valves to prevent backflow of blood. Capillaries are the smallest and thinnest blood vessels that connect arteries and veins. They exchange substances with the tissues through their permeable walls.
Blood pressure is the force exerted by the blood on the walls of the blood vessels. It is measured by two values: systolic pressure and diastolic pressure. Systolic pressure is the pressure when the heart contracts and pumps blood into the arteries. Diastolic pressure is the pressure when the heart. Blood pressure is measured by two values: systolic pressure and diastolic pressure. Systolic pressure is the pressure when the heart contracts and pumps blood into the arteries. Diastolic pressure is the pressure when the heart relaxes and fills with blood. Blood pressure is expressed in millimeters of mercury (mm Hg). For example, a blood pressure reading of 120/80 mm Hg means that the systolic pressure is 120 mm Hg and the diastolic pressure is 80 mm Hg. Blood pressure can vary depending on various factors such as age, activity, stress, diet, etc. However, a normal blood pressure range for healthy adults is between 90/60 mm Hg and 120/80 mm Hg. A blood pressure higher than this range can indicate hypertension or high blood pressure, which can increase the risk of heart disease, stroke, kidney failure, etc. A blood pressure lower than this range can indicate hypotension or low blood pressure, which can cause dizziness, fainting, shock, etc. The table below shows the blood pressure categories and what they mean for you: Systolic (top number) in mm Hg Diastolic (bottom number) in mm Hg Blood pressure category What to do --- --- --- --- Below 90 Below 60 Low blood pressure Consult your doctor if you have symptoms or underlying conditions 90-120 60-80 Normal blood pressure Maintain or adopt a healthy lifestyle 120-129 Below 80 Elevated blood pressure Maintain or adopt a healthy lifestyle 130-139 80-89 Stage 1 hypertension Maintain or adopt a healthy lifestyle. Talk to your doctor about taking one or more medications 140 or higher 90 or higher Stage 2 hypertension Maintain or adopt a healthy lifestyle. Talk to your doctor about taking more than one medication 180 or higher 120 or higher Hypertensive crisis Call 911 or seek emergency medical help Excretion
Excretion is the process of removing waste products from the body. Waste products are the substances that are produced during metabolism and are harmful or useless for the body. Some of the waste products are carbon dioxide, water, urea, ammonia, uric acid, etc. Excretion helps in maintaining the internal environment of the body by regulating the pH, osmotic pressure, temperature, etc.
Excretory system and its parts
The excretory system of human beings consists of the following parts:
- Kidneys: They are two bean-shaped organs that filter the blood and produce urine. They are located on either side of the spine in the lower back. - Ureters: They are two tubes that carry urine from the kidneys to the urinary bladder. - Urinary bladder: It is a muscular sac that stores urine until it is expelled from the body. - Urethra: It is a tube that carries urine from the urinary bladder to the outside of the body. The diagram below shows the excretory system of human beings:
Urine formation and osmoregulation
Urine formation and osmoregulation involved in different parts of the excretory system are as follows:
- Urine formation: It is the process of producing urine from blood by the kidneys. It involves three steps: filtration, reabsorption, and secretion. Filtration is the process of separating water and small molecules from blood by passing it through a membrane called glomerulus. Reabsorption is the process of returning some of the filtered water and molecules back to. the blood by the tubules. Secretion is the process of adding some waste molecules from the blood to the filtrate by the tubules. The filtrate that remains after these steps is called urine. Urine contains water, urea, salts, and other substances that are not needed by the body. - Osmoregulation: It is the process of maintaining the water and salt balance in the body by the kidneys. Osmoregulation helps in preventing dehydration or overhydration of the cells and tissues. The kidneys adjust the amount of water and salts that are reabsorbed or secreted by the tubules according to the osmotic pressure of the blood and the urine. The osmotic pressure is the pressure that is exerted by the dissolved substances in a solution. The hormones that regulate osmoregulation are antidiuretic hormone (ADH) and aldosterone. ADH increases the water reabsorption by the tubules, while aldosterone increases the salt reabsorption by the tubules. Conclusion
In this article, we have learned about the life processes that are essential for the survival of living organisms. These include nutrition, respiration, transportation, and excretion. We have also learned about the different types and modes of these processes and how they differ in plants and animals. We have also learned about the various organs and systems that are involved in these processes and how they function and regulate. We hope that these notes have helped you in understanding this chapter better and preparing for your exams.
FAQs
Here are some frequently asked questions related to this chapter:
- Q: What is the difference between ingestion and digestion? - A: Ingestion is the intake of food through the mouth, while digestion is the breakdown of food into simpler molecules by mechanical and chemical means. - Q: What is the difference between aerobic and anaerobic respiration? - A: Aerobic respiration is the type of respiration that occurs in the presence of oxygen, while anaerobic respiration is the type of respiration that occurs in the absence of oxygen. - Q: What is the difference between xylem and phloem? - A: Xylem is a vascular tissue that transports water and minerals from the roots to the leaves, while phloem is a vascular tissue that transports food from the leaves to other parts of the plant. - Q: What is the difference between arteries and veins? - A: Arteries are blood vessels that carry oxygenated blood from the heart to different parts of the body, while veins are blood vessels that carry deoxygenated blood from different parts of the body to the heart. - Q: What is the difference between urine and urea? - A: Urine is a liquid waste product that is produced by the kidneys and excreted from the body, while urea is a nitrogenous waste product that is formed by the breakdown of proteins and is a component of urine. Urea is also produced by the liver and transported by the blood to the kidneys. 44f88ac181