Life Processes (Biology) PDF

Summary Chapter 1. Life Processes > Living beings are complex organisations of molecules which perform various life processes like growth, respiration, digestion, reproduction, excretion etc., which makes them different from non-living. > The basic processes or functions p...

Summary Chapter 1. Life Processes > Living beings are complex organisations of molecules which perform various life processes like growth, respiration, digestion, reproduction, excretion etc., which makes them different from non-living. > The basic processes or functions performed by living organisms to keep them alive are called life processes. LIFE PROCESSES Nutrition Respiration Transportation Excretion Nutrition > Nutrition is defined as the process of intake of nutrients and its utilization by an organism in various biological activities. MODES OF NUTRITION Autotrophic Heterotrophic [Organisms prepare their own food. (They depend on autotrophs for their food. Example :Plants, Algae) Example: Animals, Humans] Holozoic Parasitic Saprophytic [The process of intake of solid or liquid [The process of obtaining food (The process of obtaining food food by ingestion process, conversion directly from the body of host from the dead or decayed of complex food parti-cles to simpler either by living on its surface organisms. form by digestion, assimilation and or inside the body of host. Example: Yeast, Mucor, Mush finally removing the undigested food. Example:Worms.] rooms.] Example : Amoeba, Humans.] In autotrophic mode of nutrition, organisms prepare their own food and they are called autotrophs. Organisms prepare food by the process of photosynthesis. > Photosynthesis is the process by which chlorophyll containing cells prepare glucose using carbon dioxide and water in presence of light energy and oxygen gas is released as a by product during this process. > 6C0, + 12H,0u CHO, +6O, +6H,0 (Equation for photosynthesis] Chlorophyll PHOTOSYNTHESIs Conditions necessary Steps Site of this process Carbon Dioxide [from air passes through stomata present on Light Reaction Dark Reaction Chloroplasts (double surface of leaves.] [occurs in grana] (occurs in stroma) membrane bound organelle Water (absorbed by which contains chlorophyll] roots from soil] Absorption of Reduction of Light Energy (trapped by light energy by carbon dioxide chiorophyl chlorophyll to carbohydrates Chlorophyll (present in Photolysis of water to chloroplasts] produce hydrogen and oxygen  | 206 | Heterotrophic Nutrition BASED ON THEIR FOOD [EATING HABITS] Herbivores Carnivores Omnivores (They are plant eaters] (They eat other animals] (They eat both plants and animals] Example : Cow, goat, sheep, etc. Example: Lion, tiger Example : Man Steps of nutrition in animals STEPS OF NUTRITION IN HUMAN BEINGS Assimilation Ingestion Digestion Absorption Egestion [Process of [Conversion of [Process of passing [Absorbed food (Removal of taking of food large insoluble of digested food taken by body undigested food by the body.] molecules into throught the cells for its growth, from the body.] smaller and intestinal wall repair and simpler forms.] into bloodstream.] reproduction etc.] In human beings Food is crushed The digested food The absorbed food The undigested we take the food with the help of is absorbed by passes into blood food from small through our teeth and enzyme intestinal walls stream, through intestine passes mouth. ptyalin present through finger like blood it reaches into large intestine in saliva, acts projections called the cells and is water and salts upon starch present villi. utilised by cells are absorbed and in food to convert to obtain energy undigested solid into simnple sugar. for growth, are removed in repair etc. the form of faeces. The food in form of bolus is transferred to stomach by peristaltic movement through oesophagus. In stomach food is digested by action of gastric juice secreted by gastric glands. Mainly enzyme pepsin acts upon proteins to convert into peptones and proteases. Then food passes to small intestine where remaining food is digested by actions of pancreatic juice and intestinal juice. Fats are converted into small globules by action of bile juice secreted from liver by a process called emulsificatiorn. Organs of the Digestive System Mouth Tongue Pharynx Oesophagus Liver Stomach Gall bladder Pancreas Large intestine Small intestine Rectum Anus Summary ALIMENTARY CANAL Mouth Oral Cavity Oesophagus Stomach Small Intestine Large Intestine or Food Pipe +Receives pancreatic Salivary glands Teeth help in Gastric glands juice from pancreas No digestion [Secrete salivary mastication Food in form of secrete gastric only absorption amylase or and chewing bolus passes from juice of excess water, ptyalin] of food mouth to stomach some salts and Ptyalin acts through oesopha Tongue helps 8us by peristalsis Gastric juice Contains Amylase Lipase Typsin finally the undigested residue is left Upon ststarch to in mixing of pepsin which Starch Lipids Peptones, behind convert to food with converts to simple to fatty proteins maltose saliva proteins to sugars acids to peptides peptones and glycerol + Intestinal juice Secretes enzymes which completes the conversion of proteins to amino acids, carbohydrates to glucose, fats to fatty acidssaand glycerol +Bile from liver Emulsify large fat globules to smaller Ones Nutrition in Amoeba Holozoic nutrition in Amoeba Amoeba Pseudopodia The food is endosed senses food, Surrounds the food. in a food vacuole (ood + water). 6 Enzymes from the Food is digesteo and onm are soluble are Undigested the absortbed and Waste is tood vacuole, assimlated (used up). oxpeled. Respiration > Respiration is a biological process by which glucose is oxidized to release energy in the form of ATP which is the energy currency of the cell. CH,0, +60,Sunlig 6CO, +6H,0 +Energy [Equation for respiration) During aerobic respiration, 38 molecules of ATP are released whereas during anaerobic respiration only 2molecules of ATP are released. Tobacco is a plant and its leaves are smoked, chewed, or sniffed for a variety of effects. Tobacco contains nicotine, an addictive substance. Smoked tobacco products include cigarettes, cigars, bidis, and kreteks. > Smoking can destroy the cilia or tiny hairs in the airway that keep dirt and mucus out of lungs.  RESPIRATION Breathing Cellular or Tissue Respiration In aquatic organisms like In amoeba exchange of In plants exchange In humans respiratory fishes exchange of gases gases occurs by simple diffusion ofgases occurs organs are lungs occurs through gills through its body surface through stomata CELLULAR RESPIRATION Aerobic Anaerobic [In presence of oxygen] [In absence of oxygen] Glucose Glycolysis Kreb's Cycle (Glucose a6 carbon In presence of excess Pyruvic acid compound breaks into Supply ot Oxygen a 3 carbon compound pyurvic completely pyurvic acid in cytoplasm] breaks down into carbon dioxide and Lactic acid Ethanol and water in mitochondria) [In muscles of human carbon dioxide beings during strenous [In yeast during physical exercise) fermentation] Breathing Process in Humans BREATHING IN HUMANS Air passes through During inhalation Air from nasal Air from trachea During exhalation, nostrils where the ribs moves outwards, cavity moves to goes to bronchi and ribs moves inwards inhaled air is diaphragm moves pharynx, larynx then to smaller and diaphragm moves filtered by hairs and downwards so and then into bronchioles and into its original mucus membrane chest cavity trachea [wind pipe] finally to alveoli position, thus thoracic lining nasal cavity increases and air where exchanges cavity decreases and is forced inside of gases occurs air is expelled out from lungs through nostrils Transportation The essential substances like food, water, oxygen etc., need to be carried from one part of the body to another which is done by transport system. > Arteries carry oxygenated blood except pulmonary artery. > Veins carry deoxygenated blood except pulmonary vein. > Capillaries occurs. are thin walled blood vessels where exchange of gases and materials like food Valves allow the blood to flow in one direction i.e, they prevent back flow of the blood. Summary When blood flows from atria to ventricles atria contracts and ventricle relaxes, this is called ventricular diastole. > When blood flows from ventricles to blood vessels, ventricles contract and atrium relaxes, this is called ventricular diastole The force exerted by blood on the walls of blood vessels is called blood pressure. The normal blood pressure of human beings is 120/80 mm of Hg. > As blood flows in our heart twice so circulation in human beings is called double circulation. TRANSPORTATION In human beings In plants Xylem carries Water and water and minerals are salts from mainly rans roots to ported through tracheids or Lymphatic Blood vascular Blood leaves and system system other parts vessels Blood cells of plant It contains Plasma Lymph Phloem Transportation mainly [Transport of water and food, gases, RBCs conducts Iymphocytes food from minerals has which fight nitrogenous [carry oxygen] three process wastes, etc.] leaves to against infection WBCS other parts -Lymphvessels [Immunity] of plant Blood vessels Platelets Lymph nodes Arteries (Blood Food is mainly Lymph capillaries Veins clotting] translocated by sieve tubes of Capillaries phloem in dilute Heart (Contains two atria and two aqueous solution form ventricles, main pump organ] Absorption of Ascent of sap Loss of excess water and minerals by root pressure water in form from soil to root or transpiration of vapours by hairs by osmosis pull process of and active transport transpiration process respectively MECHANISM OF BLOOD CIRCULATION De-oxygenated blood from diferent parts of the body through venacava enters into right atrium of heart Then it moves to right ventricde through tricuspid valve Blood from right ventricle goes to lungs by pulmonary artery for purification Oxygenated blood from lungs comes to left atrium by pulmonary veins Then blood moves to left ventricle through bicuspid valvde Finally by aorta oxygenated blood is transported all over body from left ventricle Double Circulation Lung copillarics Pulmonary artery to lungs Pulmonary veln fronm lungs Vena cava Aorta to from body body Capillaries of body organs apart from the lungs Excretion EXCRETION Excretion in human beings Excretion in plants Oxygen gas produced during photosynthesis is removed through stomata Carbon dioxide gas produced Excretory organs Steps involved in during respirationnis expelled process of excretion out through stomata A pair of kidneys Some released directly to soil, [Nephrons are structural Ultrafiltration waste stored in leaves fall off and functional units] [Blood is fltered through glomerulus and collects in Excess water removed by Apair of ureters Bowman's capsule as it flows transpiration [Urine passes through ureter to bladderl with high pressure known as Some in form of resins, gums glomerular filtrate] Urinary bladder Some waste products stored (Stores urine] Selective reabsorption in vacuoles (Glomerular iltrate contains many Urethra useful substances like glucose, water, Removes urine to outside salts which are selectively reabsorbed when bladder is full] in different parts of nephron] Tubular secretion (Some harmful substances are secreted from tubules of nephron to the formed urine) > The process of removal of mainly nitrogenous waste substances from our body is called excretion. > In case of kidney failure due to infections or injury or other factors artificial kidney is used. > Artificial kidney is adevice that removes nitrogenous wastes from our body by dialysis. Organ donation is the donation of biological tissue or an organ of the human body, from a living or dead person to aliving recipient in need of atransplantation. Organ transplantation is the only option to save lives in patients affected by terminal organ failures and improve their quality of life. Summary Chapter 2. Control and Coordination > Movements is one of the important characteristics of living beings. Changes in the environment to which the organisms respond and react are called stimuli. Various organs or parts of the body of an organism works in a coordinated and proper manner to produce a reaction to the given stimulus which is called coordination. Nervous system and endocrine system are the two systemns which play a major role in control and coordination. Coordination in Animals Human Nervous System > Nervous system coordinates and controls all the voluntary and involuntary actions by transmitting nerve impulses to and from different parts of the body. > Neuron is the structural and functional unit of nervous system. NEURON Axon Dendrites Cyton or Cell Body [It conducts impulses [They are the site which receive [It receives impulses from away from cyton] impulses and conduct impulses to cyton] dendrites] It is a long process from They are fine, branched projections It contains a well defined cyton surrounded by of cyton nucleus with granular myelin sheath cytoplasm and various cell of organelles Synapse is a point of contact between axon terminals of one neuron with dendrites of another neuron separated by a minute gap. > The terminals of axon have swollen ends which contain a chemical called acetylcholine -a kind of neurotransmitter. TYPES OF NEURON Sensory Neuron Motor Neuron Association Neuron (They carry impulses from (They carry impulses from (They connect sensory receptors to central nervous system] central nervous system to effector] and motor neurons] > Brain is protected inside cranium of skull. > Brain and spinal cord are protected by a three membranous layer called meninges. The three layers of meninges are Dura mater, Arachnoid, Pia mater. Space between covering membrane is filled with a fluid called cerebrospinal fluid which protects brain and spinal cord from shock or injury. > Cerebrum of brainis divided into four lobes Frontal lobe, parietal lobe, temporal lobe and occipital lobe. > There are 31 pairs of spinal nerves - 8 pairs in neck region, 12 pairs in thorax, 5 pairs in lumbar, 5 pairs in sacral and 1 pair in coccygeal region. |212 | HUMAN NERVOUS SYSTEM Central Nervous System Peripheral Nervous System Peripheral Nervous System Brain Cranial nervous [12 pairs] Spinal cord Spinal nerves Sympathetic Parasympathetic [Centre of reflex [31 pairs) nervous system nervous system action] [Prepare the body (Restores the body for violent action] to normal conditions after violent act is over] Forebrain Midbrain Hindbrain [A small tubular part Cerebrum involves reflexes of Cerebellum (Seat of memory, eyes and ears] [Controls and coordinates muscular activities intelligence, will and balance of the body] power, consci Pons ousness] Thalamus [Connects cerebellum and medulla oblongata] Diencephalon - (Relays pain and Medulla oblongata pressure impulses] [Controls involuntary actions, actions of Hypothalamus internal organs) (Control body temperature, aygland, centre of thirst, etc.] > Sympathetic and parasympathetic nervous system are antagonistic in functions. Spinal cord is the extension of medulla oblongata which runs through our vertebral column along the whole length of backbone. > Reflex arc is the shortest route taken by an impulse from receptor to effector. Stimulus ’ Receptors ’ Sensory neuron ’ Brain or Spinal cord ’ Motor neuron Effector organ ’ Response. ACTIONS Voluntary Involuntary or Reflex Action [Performed consciously or [Automatic, quick, sudden response according to our will] performed unconsciously not under the control of our will]) Examples :Changing TV channel by pressing button of the remote, Taking Examples : Withdrawal of our hand an apple with hand and eating it etc. suddenly on touching aahot plate, Shivering when it is too cold etc. Summary Hormonal Control in Humans HUMAN ENDOCRINE SYSTEM Pituitary Gland Thyroid Gland Parathyroid Gland Adrenal Gland Pancreas Gonads [Master Gland] ThyroxinRegulates Parathormone Adrenaline calcitonin basal (Regulates ion [Emergency metabolism balance in our hormone] Anterior lobe body] Insulin Glucagon Somatostatin ACTH TSH FSH Prolactin Growth hormones [Decreases (Increases [Deficiency causes sugar level sugar level dwarfism and in blood] Stimulates Stimulates Stimulates OVersecretion causes in blood) adrenal thyroid to production gigantism] cortex secrete of milk in Deficiency causes thyroxin mammary diabetes mellitus Testis gland [Produces male Posterior lobe Oxytocin hormone testosterone] [Contraction of uterus during child birth] Ovaries ADH [Produce oestrogen, [Increases water reabsorption by kidney tubules] progesterone, relaxin] Deficiency leads to diabetes insipidus > Hypothalamus secretes neurohormones and it also controls secretions of pituitary gland. > The body ishasnottogood. hormones maintain a normal If there is a rise state becauselevel in hormonal too much or very secretion the hormones less secretions of has to be reduced. Similarly ifftthereis low hormonal level, its secretion has to be increased which is maintained by feedback mechanism. Coordination in Plants > There are two types of movements: (i) Growth dependent movement. (iü) Growth independent movement. > stimulus. Curvature movements are changes in orientation of some plant parts in response to COORDINATION IN PLANTS Hormonal Control Movements of Plants Growth promoting hormones Auxin Tropic Movements Nastic Movements [Cell elongation, [Directional growth [Non-directional differentiation, movements of plant parts movements due to turgour regulate plant in response to stimulus changes which does not growth movements] like light, water, chemicals, involve growth) Gibberellins gravity, etc.] Growth inhibiting Seismonastics hormones [Stem elongation, Photoprophism [Movement in induce parthenocarpy, [Movement of plant response to Abscisic acid stimulates flowering] parts in response to touch) Promotes senescence Cytokinins light] Example : Drooping of leaves of of leaves, dormancy [Promotes cell division, Geotropism touch-me-not plant in seeds and buds delay senescence, [Movement of plant promotes opening of parts in response Nyctinastic stomata to gravityl [Diurnal variations in position of leaves and Ethylene Hydrotropism flowers during day and [Growth and ripening [Movements of plant of fruits, breakingof parts in response night] dormancy in seeds Photonastic to water] and buds] Thermonastic Chemotropism [Movement of plant parts in response to chemicals]  | 214 | Chapter 3. How Do > Reproduction is the biological process by Organisms which new Reproduce individual organisms (offspring) are produced from their parents. Reproduction is a fundamental feature of all known life. Each individual organism exists as the result of reproduction. > The inheritance of features fromn parents can be chromosomes present in the nucleus of the cell. transferred to their offsprings through Basic event in reproduction is the creation of a DNA > Some changes in DNA copying produces variations incopy. organisms known as mutations. TYPES OF REPRODUCTION Asexual Reproduction (It involves single parent and Sexual Reproduction there is no gametes formation.] [It involves mixing of genetic material through fusion of gametes and two parents are involved.] Spore formation (Reproduction occurs by formation of spores. Examples: Mucor, Rhizopus] Fission [When an organism splits into two or more individuals by mitotic divisions) Fragmentation (The body of organisms divide into smaller Binary Multiple (Division of a parent cell [Division of a parent cell fragments and each fragments grow into new into two identical into several small individuals. Example: Spirogyra] daughter cells] daughter cells] Regeneration Examples : Binary fission Examples : Fission in [The ability of an organism to in amoeba, paramecium, plasmodium malarial regenerate its lost or injured part of the leshmania parasite body. Example : Regeneration in Planaria] Budding [Production of new individuals from outgrowth of the parent. Example : Budding in Hydra] Vegetative propagation in plants is also an example of asexual reproduction. New plants can be grown from different vegetative parts of the > Some plants like Bryophyllum develops plants like roots, stems, leaves etc. new plants. adventitious buds on the leaves which develops into > Modified tuberous roots like sweet potato can be soil. propagated vegetatively when planted in > Artificial methods of vegetative propagation includes cutting, layering grafting etc. SEXUAL REPRODUCTION In Plants In Human Beings Flower is the main reproductive organ Pollination Male Reproductive Female Reproductive (Transfer of pollen grains System System from anther of the stamen to the stigma of carpel) Testes Ovaries Fertilization Vas deferens Oviducts (Fusion of male and Urethra Uterus female gamates Self Cross Penis Vagina to form zygote] pollination pollination Vulva ranster of pollen grains from Transfer of pollen grains from ant rof a flower to the stigma anther of one flower to stigma of the same flower or flower of another flower of different borne on the same plant. plant but of same species. Summary The parts of a flower are calyx, corolla, androecium and gynoecium. > Calyx is the outermost whorl of a flower which is a collection of sepals mostly colour and they are protective in function. green in > Corolla is the collection of petals, they are brightly coloured and helps in attraction of insects for pollination. Androecium is a collection of stamens which are the male reproductive organs of a flower. A stamen consists of anther and filament. Anther contains pollen sacs in which pollen grains are produced. Pollen grains contain male gametes. Gynoecium is a collection of carpels which are the female reproductive organs of a flower. > A carpel consists of stigma, style and ovary. > The ovary contains ovules which contains the female gametes. > Double fertilization is a complex fertilization mechanism in flowering plants. This process involves the joining of a female gametophyte (megagametophyte, also called the embryo sac) with two male gametes (sperm). > Ovules grow into seeds and ovaries grow into fruits after fertilization. Stigma Pollen tube Antipodal Polar nuclei Embryo sac Egg cel -Synergid Micropyle Gonads are whereas primary ovaries sex organs are female in humans. gonads Testes eggs. which produce are male gonads which produces sperms Testes are found within sac like structures called scrotum. Vas deferens or sperm ducts carry sperms from testis. Ovaries produce eggs. The fertilization of egg with sperms occurs at oviduct. After fertilization zygote is formed which develops into embryo that grows in uterus to afull term baby in about 280 days which is called gestation period. If fertilization does not occur the egg disintegrates and along with blood and mucus it comes out through the vagina. This cycle occurs every month in females known as menstrual cycle. METHODS OF POPULATION CONTROL Barrier Chemical Natural Surgical Methods IUCDs Methods Methods Methods [Prevents entry of (Some chemicals (Examples:Copper-T Tubectomy is done in sperms into female are used like which is placed in genetical tract) vaginal pills, uterus that prevents females where a piece implantation of of oviduct is cut and ligated. Examples :Condoms, oral pills) Vasectomy is done in males Diaphragam etc. Ygote) where a piece of vas deferens is removed and ligated. > To avoid rapid growth of population some preventive measures are taken which is called birth control. The infectious diseases which spread from an infected person to a healthy ones through sexual contact are called Sexually Transmitted Diseases or STDs. Examples are AIDS, syphilis, gonorrhea.  | 216 | Chapter 4. Heredity and Evolution > Genetics is the process of transmission of body features from parents to offsprings and the laws related to transmission. In other words we can say Genetics deals with study of both heredity and variations. > The word " Genetics " was coined by William Bateson in 1906. Heredity [It deals with transmission of characters from one generation to the next generation] Variations Inherited Traits [It is the differences in traits (They are the characters that are among the individuals of a species] transmitted from generation to generations] Expression of Traits Rules for Inheritance of Traits [Traits are expressed by synthesis [Mendel's contribution] of a particular protein responsible for the expression of that particular trait in an individual] Mendel's Experimental Laws Formulated Techniques by Mendel Monohybrid Dihybrid Law of Law of Law of Cross Cross Dominance Segregation Independent Assortment > Variations are mainly seen during sexual reproduction due to following reasons: () Crossing over during meiosis process. (ii) Alterations in genetic material due to mutations. (iüi) Mixing of female and male gametes that come from two different individuals i.e., father and mother. Gregor Johann Mendel is considered as "Father of Genetics." He had formulated the Laws of Inheritance by performing hybridization experiments on Pisum sativum - Garden pea plant. He had studied seven contrasting pairs of characters in pea plants. (i) Height of the plant - Tall or short (ii) Colour of flower- Purple or white (ii) Shape of seed - Round or wrinkled (iv) Colour of seed- Yellow or green (v) Colour of pod - Green or yellow (vi) Shape of pod - Inflated or constricted (vii) Position of flower -Axial or terminal The cross between tne tw breeding varieties of an organism taking into account only a single character at a time is Pllod monohybrid cross. > Example of monohybrid cross : A pure tall pea plant is crossed with pure dwarf pea plant. In Fgeneration tall pea plants are produced with heterozygous condition i.e., they carry both dominant and recessive alleles. When these plants are crossed they give tall and dwarf plants in the ratio 3:1 which is also called phenotypic ratio and their genotypic ratio is 1:2:1. Parental Generation Pure Tall Pea Plant Pure Dwarf Pea Plant tt Gametes T X Tt (Tall] Summary FË Generation Tt (Tal] Tt [Tal] Gametes F2 Generation Tt tt TT [Tall] Tal [Tal] (Dwarf) Genotype :1:2:1 Phenotype:3:1 > The cross between the two pure breeding varieties of an organismn taking into account two characters at a timne is called dihybrid cross. When a pure pea plant with round yellow seeds is crossed with pure pea plant having green wrinkled seeds, in F generation hybrid plants with round yellow seeds are produced. But again when these plants are crossed they produce round-yellow, round-green, wrinkled yellow, wrinkled-green in the ratio 9:3:3:1, which is the phenotypic ratio. Parental Generation Pure pea plants with X Pure pea plants with round, yellow seeds wrinkled, green seeds RRYY Gametes RY y RrYy [Pea plants with round, F Generation yellow seeds) Rty RrYy Gametes RY Ry rY RY Ry Gametes RY Ry y RY RRYY RRYY RrYY RrYy Ry RRYy RRyy RrYy Rryy RrYY RrYy rrYY rrYy ry RrYy Rryy rrYy ryy Phenotype:9:3:3:1 Based on Mendel's breeding experimernts three Laws were deduced. > Law of Dominance: The phenomenon of appearance of only one of the two contrasting traits in F1 generation is called dominance. The other character remains suppressed which is known as recessive character. > Law of Segregation : At the time of reproduction when gametes are formed the factors segregate so that each gamete receives only factor of each character. This is called Law of purity of gametes. > the Lawtwo of independent assortment : At the time of reproduction, two pairs of factors of each of in a dihybrid cross segregated independently during gamete formation and randomly formed combinations in F; generation. Inheritance of factors controlling a particular trait in an organism is independent of the other. > The mechanism by which sex of an individual is determined when it begins its life is called sex determination. In human beings, sex is determined by XX-XY mechanism. Males have XY sex chromosomes whereas females have XX sex chromosomes.  |218 | > In some reptiles sex is determined by environmental factors. > Gene is afragment of DNA molecule that has a particular nucleotide sequence which encodes for a particular protein. Evolution is the constant process of gradual change occurring in an organism since the origin of life which gives rise to varietyof complex organisms onthe surface of earth. Evolution Inherited and acquired traits Speciation Evidences that help in training (Inherited traits are controlled [Origin of new species from evolutionary relationships by specific genes and are existing ones due to reproductive isolation] Morphological transmitted through and anatomical -Homologous generation] Genetic drift evidences organs Factors [It leads to alteration Palantological Vestigeal [Acquired traits are leading to of gene frequency where evidences organs developed during the speciation genes of certain traits life of an organism are eliminated] Embryological Analogous which cannot be evidences organs Natural selection transmitted through generations] [Charles Darwin gave this concept) Geographical isolation [It leads to reproductive isolation where individuals are checked for interbreeding] Genetic variations [During sexual reproduction genetic variations lead to formation of new species] > The struggle for survival within population eliminates the unfit individuals and only those with favourable variations survive and then they multiply and pass on these variations to next generation. Here the nature selects the traits which are favourable to the species in its environment and this phenomenon is called natural selection. A This concept was given by Charles Darwin in his book "Origin of species." > A The four factors that lead to speciation are geographical isolation, natural selection, genetic variations, genetic drift. A Genetic drift alters the gene frequency of remaining population. Genes of certain traits in a Small population gets eliminated due to death of orgarnisms because of natural calamity or migration of organisms to other region is called genetic drift. > A Homologous organs perform different functions in different species but have same basic structure and similar embryonic origin. Examples : Forelimbs of birds, man, lizard, frog. Analogous organs perform same function in different species but they are quite different in basic structure and origin. Example: Wings of insects and birds. > Vestigial organs are in reduced and useless form to the possessor but they are fully developed and functional organs in ancestors. Examples : Vermiform appendix, nictitating membrane, wisdom teeth present in humans. A Lamarck gave the concept of "Use and disuse of organs". > A Fossils which are the remains or impressions of dead plants and animals that lived in remote past provide direct evidence of evolution. AA The study of fossils is called paleontology. Fossils are formed in sedimentary rocks. > Fossil bird Archaeopteryx is a connecting link between reptiles and birds. > A The early stages of embryo of vertebrates resemble a lot in shape and structure which shows that vertebrates have evolved from a common ancestor. A Artificial selection is the process by which man selects traits useful to him for improving the qualities of domesticated plants and animals. A Evolution should not be equated with progress. A> Evolution does not proceed as a ladder of progress but as branches of tree. Summary Evolution not as ladder Evolution as branches of progress of tree > Humans are closely related to chimpanzees and apes. They have a common ancestor which diverged into severall forms to give rise to apes, human, chimpanzees etc. > Human beings belong to species Homo sapiens. The earliest members were traced in Africa. From there they spread to the whole continent and some migrated to other parts thus spreads to the whole world.  I220 | Chapter 5. Our Environment Environment is everything that is around us which includes both biotic and abiotic components. > Abiotic components are the non-living components i.e., the physical factors like tempera ture, light, wind, water, humidity, soil, minerals, etc. > The biotic components are the living organisms like plants, animals, human beings etc. Both biotic and abiotic components interact with each other to form the environment as a whole. > An ecosystem includes all living organisms along with the abiotic components which interact with each other to maintain a balance in the nature. > The term ecosystem was introduced by Tansley in 1935. ECOSYSTEM Types Components Abiotic Components -Aquatic Natural Climatic [Found and operated Marine Freshwater Factors Edaphic Factors by nature without -Terrestrial - (Temperature, (Soil, minerals, interference of human] light, wind, water] pH] Artificial Forest Desert Grass Biotic Components lands Created or modified by Producers Consumers human beings. Decomposers Examples : Garden, park (They produce [They obtain food their own food by from the dead aquarium etc. the of Primary Secondary Tertiary Quat- producers > A Producers are mainly autotrophs. photos oroCe sis Mainly green plants] ernary and consumersl A Consumers cannot prepare their own food. They depend on autotrophs directly or indirectly for food. They are primary consumers [which eat plants or plants products), secondary consumers. [Feed upon primary consumers], tertiary consumers [feed upon secondary consumers] quaternary consumers [feed upon tertiary consumers and are at the top most level of food chain]. > Decomposers like bacteria, fungi etc., feed upon the decay of dead producers and consumers. > The transfer of food energy from plant sources through a series of organisms in an ecosystem is known as food chain. > The interlinking sequence starting from an autotroph to herbivores, carnivores and top most level consumers is called a food chain. Secondary Consumer Producer Primary Tertiary Consumer Consumer Decomposer Fig : Food chain Summary > A food chain shows one path how energy in form of food flows from producers to Consumers. > A food web shows many paths i.e., it is a network of food chains where an organism eat several types of organisms or eaten by many different organisms. Jaguar (Carnivore) Fox Deer Squirrel (Omnivore) (Herbivore) (Herbivore) Pine Tree (Producer) Fig: Food web > The distinct sequential steps in the food chain where transfer of energy occurs are referred to as different trophic level, which is represented as under. Tertiary consumer Secondary consumer Primary consumer Producers Trophic Level > Energy flow in an ecosystem is unidirectional i.e., it flows from autotrophs to herbivores to secondary consumers, tertiary consumers in one direction. > At each trophic level some amount of energy is lost. Lindeman suggested a Ten percent rule which states that the rate of transfer of energy from one trophic level to the next trophic level is of the order of 10%. For example if energy produced by a green plant is 100 calories only 10 calories is available to herbivores then 1 calorie to secondary consumers and very less energy i.e., 0.1 calorie to tertiary consumers. So at each trophic level the energy goes on decreasing hence a food chain or food web consists of 3-4 levels or maximum 5. > Biomagnification is the process which involves the progressive increase in the concentration of toxic or harmful substances at different trophic levels. So the organisms that are at the top of food chain have accumulated a maximum concentration of harmful chemicals in their body. Example: Accumulation of pesticides like DDT.  ENVIRONMENTAL DEPLETION Types of wastes Effects on our environment Greenhouse effect [Due to increase in Biodegradable Non-biodegradable concentration of waste waste (They can be degraded [They cannot be greenhouse gases the temperature of into simpler forms by degrated into simpler earth is gradully methods.) the action of microbes forms by the action increasing leading like bacteria, fungil of microbes] to greenhouse effect] Examples: Sewage, Examples: Plastics, household garbage, paper. metals, DDT, glass. Global warming is a Consequence of greenhouse effect. Ozone layer depletion [Due to use of CFCs the layer of ozone present in stratosphere is gradually depleting leading to serious consequences] > Ozone layer prevents the harmful UV rays of sun from entering to the earth's surface. A CFCs which is the main cause of depletion of ozone layer is found mainly in aerosol sprayers, refrigerators, air-conditioners etc. > The depleting ozone layer has many harmful consequences like it causes cancer, causes genetic variations due to mutation, damages our eyes, decline of photosynthesis rate in plants. > The first ozone hole was discovered over Antarctica.