NOTES BY ADITYA SIR
Something which is ‘living’ (not dead) is said to be ‘alive’. ‘alive’ means ‘having Life’. Those things which are alive are called ‘living thing.
• What criteria do we use to decide whether something is alive?
The most important criterion to decide whether something is alive (or not) is the Movement. Movement is one of the most important signs of life in an organism. All the living things (which are alive) move by themselves without any external Help. The plants can only move parts of their body such as leaves, flowers, shoots and roots. The plant parts move towards a stimulus such as sunlight, gravity or water, etc. For example, the leaves and flower of a sunflower plant move by bending towards the sun so as to face the sunlight .The leaves of a Mimosa pudica plant (sensitive plant) move by folding up when touched with a Finger. Non-living things (which are not alive) cannot move by themselves.
• What are Life Processes?
The basic functions performed by living organisms to maintain their life on this earth are called life processes. The basic life processes common to all the Living organisms are: Nutrition and Respiration; Transport and Excretion; Control and Coordination (Response to stimuli); Growth; Movement and Reproduction.
• What is Nutrition?
The process of taking in food (consuming) and utilising it for metabolic activities is known as nutrition.
• What Is The Need Of Nutrition ?
ü Organisms need energy to perform various activities. The energy is supplied by the nutrients.
ü Organisms need various raw materials for growth and repair. These raw materials are provided by nutrients.
• Define Nutrient?
A nutrient can be defined as a substance which an organism obtains from its Surroundings and uses it as a source of energy or for the biosynthesis of its Body constituents (like tissues and organs). For example, carbohydrates and Fats are the nutrients which are used by an organism mainly as a source of Energy whereas proteins and mineral sats are nutrients used by an organism For the biosynthesis of its body constituents like skin, blood, etc.
• Types of nutrition
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Autotrophic nutrition is that mode of nutrition in which an organism makes (or Synthesizes) its own food
ü from the simple inorganic materials like carbon Dioxide and water present in the surroundings. Those organisms which can make their own food from carbon dioxide and Water are called autotrophs.
ü Heterotrophic nutrition is that mode of nutrition in which an organism cannot make (or synthesize) its own food from simple inorganic materials like carbon Dioxide and water, and depends on other organisms for its food. A heterotrophic Organism is a consumer which derives its nutrition from other organisms. Those organisms which cannot make their own Food from inorganic substances like carbon dioxide and water, and depend on Other organisms for their food are called heterotrophs.
ü Some organisms feed on dead and decaying organic matter. This mode of nutrition is called saprophytic nutrition.
ü Some organisms feed on another organism and in turn cause harm. This is called the parasitic mode of nutrition.
ü Some organism take food by ingestion through mouth and then digested the food after this obtain the nutrition this type of mode of nutrition is Holozoic mode of nutrition.
Nutrition in plants
• Photosynthesis : it’s a process by which a green plant make their own food in the form of carbohydrate in the presence of sunlight, by using water and carbon dioxide. Carbohydrate provide energy to the plant, and extra food stored in the form of starch, in case of animal it’s an glycogen. Photosynthesis occur in leaf inside the chloroplast (it’s a green dot when we see cross section of leaf) .inside the chloroplast chlorophyll is present.
Light reaction – Thylakoids of Grana
Dark reaction – Stroma
• Steps Of Photosynthesis :
During the process of photosynthesis, the following events occur :
I. Absorption of light energy by chlorophyll.
II. Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen. The above processes are considered as light reaction as it can take place only in the presence of light.
III. Reduction of carbon-dioxide to carbohydrates. This is also known as dark reaction as it does not require light.
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Desert plants take up CO2 at night and prepare an intermediate which is acted upon by the energy absorbed by the chlorophyll during the day.
• Conditions Necessary For Photosynthesis
Sunlight
Chlorophyll
Carbon-dioxide
Water
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Opening and Closing of Stomatal Pore : The opening and closing of the stomata is the function of guard cells. The guard cells swell when water flows into them causing the stomatal pore to open. Similarly the pore closes if the guard cells shrink. Since large amounts of water can also be lost through stomata the plant closes these pores when it does not need CO2 for photosynthesis.
Nutrition in animals (Human being)
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In human being the nutrition is obtained by completing some process.
Ingestion: Process of taking food inside the body through mouth.
Digestion: Process of conversion of complex food particles into simpler and absorbable form by the action of enzymes.
Absorption: Process of diffusion of soluble food particles into the blood.
Assimilation: Process of utilization of absorbed food by the body cells.
Egestion: Process of removal of undigested food from the body.
Human digestive system
Digestive system consist alimentary canal and associative glands. Those organs which is responsible for ingestion, digestion, absorption, assimilation and excretion contribute the digestive system.
• Alimentary canal is 9m long in adult , it begins anteriorly with mouth and opens out posteriorly through anus. It lead into buccal cavity, buccal cavity consist freely movable tongue, teeth and salivary glands.
Mouth
ü tongue has bearing taste buds on the surface that help us to identify the taste and help in mixing the food with saliva and making bolus.
ü some animals (human) have two type of dentition over in his life this permanent and deciduous teeth because of this type of dentition its known as diphyodont , and total we have 32 teeth, they four different types so it is known as heterodont, incisors, canine, premolar and molar. It help us two masticate the food and chewing.
ü salivary gland releasing the salivary amylase. it’s an enzyme ( ptylin enzyme) which digest the starch and make the food soft. So that means the digestion starts from mouth then it enter into pharynx.
• Pharynx : it’s a short and common passage for wind pipe and food pipe. Then it goes into Oesophagus (food pipe)
• Oesophagus : the bolus enters into oesophagus and move forward by peristalsis movement (muscles contract and relax).
• Stomach : it is j shaped organ which lies on th left side of the abdominal cavity , below the diphagram. It’s a thin walled bag. The membrane of the stomach secret gastric juice that contain Hcl, Mucus, and enzymes . The stomach stores food for 4-5 hours. Gastric gland secrete pepsinogen enzyme which is inactive ezyme and Hcl provide tha acidic nature to pepsinogen by which it activate and become pepsin that convert protein into peptones and Proteoses and mucus provide the protective layer for stomach that protect stomach from HCl.
HCl activate enzyme and kill the bacteria that enters through food.
By the churning movement of the stomach while food mixes with juice it becomes chyme and move forward to small intestine.
• small intestine : From the stomach the food is moved to the small intestine. It is a very long tube (7 m, long and 2.5 cm. diameter) . small Intestine is the longest part of the alimentary canal and is greatly coiled and twisted. The small intestine is subdivided into three sections: the duodenum, the jejunum, and the ileum. It’s the main region where mostly digestion occurs.
Duodenum: The acidic chyme in the duodenum receives the bile secreted from the liver, the pancreatic juice secreted from the pancreas and the intestinal juice from the glands of the intestinal wall.
Bile is a yellowish-green in colour, bitter in taste, slightly alkaline fluid secreted from the liver.
Bile being alkaline in nature neutralises the acidic chyme. Bile emulsify the fat and helps in the digestion and absorption of fat.
Again the pancreas, a gland located below the stomach, secretes pancreatic juice into the duodenum through the pancreatic duct. There are three enzymes namely amylase, pancreatic lipase and trypsin, in pancreatic juice that break down carbohydrates, fats, and proteins respectively.
Glands of intestine are present in the mucous layer of the intestinal wall. These glands secrete intestinal juice, which contains various enzymes.
The enzymes present In it finally convert the carbohydrates into glucose, proteins to amino acids and fats into fatty acids and glycerol.
Jejunum: The digested carbohydrates, fats, proteins, and most of the vitamins, minerals, and iron are absorbed in this section.
The Inner lining of the small intestine is composed of up to five million tiny, fingerlike projections called villi. The villi increase the rate of absorption of nutrients into the bloodstream by greatly increasing the surface area of the small intestine.
Ileum: vitamins and other nutrients are absorbed here
• large intestine : It has three parts – caecum, colon and rectum. It absorbs water and electrolytes. And undigested material egested outside through anus.
Nutrition in amoeba
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• Respiration: it is a process by which a living being utilises the food to get energy, is called respiration. Respiration is an oxidation reaction in which carbohydrate is oxidized to produce energy. Mitochondria is the site of respiration and the energy released is stored in the form of ATP (adenosine triphosphate). ATP is stored in mitochondria and is released as per need.
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During aerobic respiration, 38 molecules of ATP are released whereas during anaerobic respiration only 2 molecules of ATP are released.
Ø When someone runs too fast, he may experience throbbing pain in the leg muscles. This happens because of anaerobic respiration taking place in the muscles.
Ø During running, the energy demand from the muscle cells increases. This is compensated by anaerobic respiration and lactic acid is formed in the process.
Ø The deposition of lactic acid causes pain in the leg muscles. The pain subsides after taking rest for some time
· Respiration in human
The human respiratory system is composed of a pair of lungs. These are attached to a system of tubes which open on the outside through the nostrils.
Following are the main structures in the human respiratory system:
Nostrils: There are two nostrils which converge to form a nasal passage. The inner lining of the nostrils is lined by hair and mucus. The mucus and the hair help in filtering the dust particles out from inhaled air. Further, air is warmed up when it enters the nasal passage.
Pharynx: It is a tube-like structure which continues after the nasal passage.
Larynx: This part comes after the pharynx. This is also called voice box.
Trachea: This is composed of rings of cartilage. Cartilaginous rings prevent the collapse of trachea in the absence of air.
Bronchi: A pair of bronchi comes out from the trachea, with one bronchus going to each lung.
Bronchioles: A bronchus divides into branches and sub-branches inside the lung.
Alveoli: These are air sacs at the end of bronchioles. The alveolus is composed of a very thin membrane and is the place where blood capillaries open. This is alveolus, where the oxygen mixes with the blood and carbon dioxide exits from the blood. The exchange of gases, in alveoli, takes place due to the pressure differential.
• 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: it is a process in which water is lost in the form of water vapour from the plants.
This process occurs mainly through the stomata, where the exchange of gases (oxygen and carbon dioxide) occurs.
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Loss of water, especially from leaves, acts as a straw effect and pulls water upwards from roots.
Transpiration also acts as an excretory mechanism in plants as it helps to get rid of excess water.
• 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 are thin walled blood vessels where exchange of gases and materials like food occurs.
Valves allow the blood to flow in one direction i.e., they prevent back flow of the blood.
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.
• Excreation: 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 a device that removes nitrogenous wastes from our body by dialysis.
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.
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• Nephron
Nephrons are the structural and functional unit of kidney.
Each kidney has millions of nephrons, and it forms the basic structural and functional unit of the kidney.
Each nephron has two parts: The malpighian body and the renal tubule.
The malpighian body is made up of a cup-like structure called Bowman’s capsule, which encloses a bunch of capillaries called the glomerulus.
They together filter waste materials along with many useful substances.
The renal tubule has regions called a proximal convoluted tubule, Loop of Henle and distal convoluted tubule.
These regions absorb useful substances back into the blood and also filter the remaining waste substances.
The output from nephrons is called urine.