10 Sc Bio Life Process Science

CHAPTER Life Processes Difference Between Living and Non-living

Living

Non-Living

Movement

Lack of Movement

Growth

Lack of Growth

Reproduction

No Reproduction

Respiration

No Respiration

Excretion

No Excretion

Repair

No repair

LIFE PROCESSES Various functions are going inside our body and inside the body of all living organisms. These functions are necessary to maintain the living being. The maintenance functions of living organisms must go on even when they are not doing anything particular. Even when we are just sitting in front of computer, even if we are just asleep, this maintenance job has to go on. The processes which together perform this maintenance job are life processes. Following functions comprise the life processes: 1. Nutrition 2. Respiration 3. Excretion 4. Growth & Repair 5. Reproduction Nutrition: Nutrition is the process of getting energy from outside sources. Next process of nutrition is to break down these sources to release energy. Process of getting nutrition can vary from organism to organism and is affected by the external environment. Based on Mode of getting food organisms can be classified as follows: 1. Autotrophs 2. Heterotrophs Autotrophs Autotrophs make their own food. All green plants are autotrophs. You must be aware that green leaves contain a pigment called chlorophyll, which makes them green. Apart from colouring purpose, chlorophyll plays a more important role of converting the Sun's photo energy to chemical energy. The process of food preparation in plant is called Photosynthesis. It involves making of Glucose with the help of Carbon Dioxide and Water in the presence of sunlight. Photosynthesis can be expressed by following chemical reaction:

6CO2 + 6H2O ---------- C6H12O6 + 6O2 Carbon Dioxide Water

Glucose

Oxygen

Glucose thus formed is used by the plant to satisfy its energy needs. The excess amount is stored as starch in various parts of the plant. Experiment to show presence of starch in a plant leaf:

 � Take a potted plant with variegated leaves – for example, money plant           

or crotons. Keep the plant in a dark room for three days so that all the starch gets used up. Now keep the plant in sunlight for about six hours. Pluck a leaf from the plant. Mark the green areas in it and trace them on a sheet of paper. Dip the leaf in boiling water for a few minutes. After this, immerse it in a beaker containing alcohol. Carefully place the above beaker in a water-bath and heat till the alcohol begins to boil. What happens to the colour of the leaf? What is the colour of the solution? Now dip the leaf in a dilute solution of iodine for a few minutes. Take out the leaf and rinse off the iodine solution. Observe the colour of the leaf and compare this with the tracing of the leaf done in the beginning What can you conclude about the presence of starch in various areas of the leaf? Iodine after reacting with starch turns its colour to blue.

Carbon Dioxide Uptake in Plants Leaves have small pores called stomata. These pores open to allow entry of CO2 inside leaves. Water flows into guard cells to swell them, which helps in opening of stomatal opening. The following figure shows the stomata with guard cells: Heterotrophs: Those organisms which are dependent on other organisms for their food are called heterotrophs. Some animals, like humans have complex digestive system to break the food into basic constituents to make them fit for oxidation. Certain organisms break the food into basic molecules outside their body then absorb them. Fungi use some enzymes to break the food outside their body. Some organisms take food from other organisms without killing them. Most of the parasites take nutrition in this way.

Human Digestive System: Human Digestive System is a complex and elaborate system. The digestive system carries out following functions: 1)Intake of Food, 2)Digestion of Food, 3)Assimilation of Food, and 4)expulsion of waste products.

Oesophagus Liver Gall Bladder Stomach Pancreas Small Intestine Large Intestine

Digestive System

Movement of Food in the Alimentary Canal: Alimentary Canal constricts and expands in rhythmic fashion. This pushes food particles forward through the alimentary canal. At every junction there is valve like structure which prevents the back-flow of food. Sometimes these valves or sphincters malfunction, which results in regurgitation of food, resulting in burning sensation in mouth and throat. Important Enzymes and their function:

Enzyme

Food Component

Final Product

Amylase (Ptylin)

Starch

Sugar

Pepsin

Protein

Peptides

Lipase

Lipid (fat)

Fatty acids and glycogen

Trypsin

Peptides

Amino Acids

Sucrase

Sucrose

Glucose & Fructose

Respiration: Breaking down of nutrients to release energy is called respiration. The way cooking gas is burnt to produce energy for kitchen the living organism burns food to release energy. A complex series of oxidation-reduction goes inside the cell to burn food to produce energy. This energy is used to carry out different activity inside a living organism. The Chemical Reaction During Respiration can be written as follows: C6H12O6 + 6O2

6CO2 + 6H2O + 674 Kcal

Oxygen is required for oxidation of Glucose during cellular respiration. In plants and smaller animals this oxygen get inside the organism by simple mechanical way like osmosis or by difference in air pressure. But in larger organisms complex system is needed to carry out transportation of oxygen inside the body and that of carbon dioxide out of the body. This process is called external respiration and is different from cellular respiration. Transportation of O2 and CO2 in human body: Following schematic diagram represents the flow of gases in the human body:

O2

O2 Arteries

Heart

Lungs CO2

CO2 Veins

O2 CO2 Cells

Haemoglobin: Red Blood Cells in the blood contain haemoglobin which carries oxygen to the cell and carbon dioxide away from the cells. Arteries: Arteries carry oxygenated blood from heart to different parts of the body. Veins: Veins carry deoxygenated blood from different parts of the body to heart. Heart: Heart functions like a pump and helps in pumping in the deoxygenated blood to lungs for oxygenation. Thereafter, heart pumps oxygenated blood to different parts of the body. Lungs: Lungs helps in sucking in oxygen from air and pumping out carbon dioxide in the air. The above scheme can help you understand how Lungs, Heart and Blood Capillaries together form a formidable air transport system inside our body. Excretion: As you may have noticed that burning petrol or diesel causes release of obnoxious fumes out of a car, our body also produces such obnoxious things. They are harmful and need to be expelled out of our body. Expulsion of harmful substances, which are byproducts of life processes is called excretion. In human body, many organs help in excreting harmful substances out of the body. For example Lungs expel carbon dioxide, skin expels some waste products through sweating, mouth expels some waste through spit, and rectum expels waste through faeces. But the main excretory organ in the human body is kidney. Kidney filters harmful substances from blood and expels them through urine. After all the metabolic activities, blood collects byproducts from different parts of the body and passes through kidney to filter out harmful products. Then only it goes to the heart for oxygenation. This is the reason a malfunctioning kidney is a life threatening condition. People with bad kidney need to undergo dialysis. In this process blood is filtered using artificial kidneys or dialysis machine.

Kidney Ureter Urinary Bladder Urethra

Excretary System

Transportation of Water in Plant: Plants have special tube like structure made of special tissues called xylem and phloem. They create capillary effect and the water rises from ground to the top of the tree. Apart from this evaporation of water through leaves creates low pressure. This low pressure creates a pull effect. Both factors combine resulting in transportation of water and minerals from roots to the top of the tree. I biological terms this is called Ascent of Sap.