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Life Processes
Mouth includes teeth, salivary glands, and tongue
...
They are of
four types – molars (6), premolars (4), canines (2), and incisors (4) in each jaw
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In total life span of humans, two sets of teeth grow – milk teeth and permanent teeth
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It contains a digestive
enzyme salivary amylase, which breaks down starch into sugar
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The food from mouth passes down the oesophagus to the stomach, through the
movement of walls of oesophagus (peristalsis)
Stomach mixes the food received from oesophagus with digestive juices
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Hydrochloric acid – creates an acidic medium and helps in digestion of
proteins
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Pepsin breaks proteins into polypeptides
Rennin changes soluble milk proteins into curd which is
insoluble
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Digestion in small intestine
It is the longest part (about 7
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It is the site where complete digestion of carbohydrates, proteins, and fats
takes place
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This process is
known as absorption
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Villi increase the surface area for more efficient food absorption
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This process
is known as assimilation
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Liver - It is the largest gland of the body and secretes bile juice
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Pancreas - Pancreas contains enzymes that help in complete digestion of
all food components
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The functions of enzymes secreted in small intestine are :
Maltase changes maltose to glucose
Sucrase changes sucrose to glucose
Lactase changes lactose to glucose
Peptidase changes polypeptides to amino acids
Digestion in large intestine
The digested food from small intestine goes into blood stream and the

undigested and unabsorbed material and water enters the large intestine
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From large intestine, the waste material is stored in rectum in the form of semisolid faeces
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This process is known as egestion
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The
process involves the consumption of oxygen and liberation of carbon dioxide and
water
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Aerobic respiration
Oxidation of food materials with the help of oxygen
Yields 38 ATP
Steps in cellular respiration
First step- breakdown of glucose (6C) into pyruvate (3C)
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It takes place in
mitochondria, energy is produced in the form of ATP
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Transportation in humans
The system that transports nutrients and collects waste materials for disposal in the
body is the circulatory system
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e
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e
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Another system, called the lymphatic system, transports immune cells
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e
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Blood, lymph- involved in transportation
Components of blood- RBCs, WBCs, platelets, and plasma
Three types of blood vessels- arteries, veins and capillaries
Arteries carry oxygenated blood, except pulmonary artery
Veins carry deoxygenated blood, except pulmonary vein
Human heart is divided into four chambers – right auricle, right ventricle, left auricle,
and left ventricle

Right side of the heart receives deoxygenated blood from all parts of the body
Left side of the heart receives oxygenated blood from lungs
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The excretory system in humans includes – a pair of kidneys, a pair of ureters, a urinary
bladder and a urethra
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It plays an important role in the
formation of urine
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8L of urine in a day
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5% urea and 2
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Nephrons are the basic filtering units of the kidneys
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Ureter carries urine to the bladder
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Urethra carries urine out of the body
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Autotrophic Nutrition
Synthesis of food by photosynthesis, Photosynthesis equation

Leaves are the sites for the synthesis of food
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Chlorophyll traps solar energy, which is used to prepare food from CO2 and
water
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Green plants absorb CO2 from atmosphere through tiny pores called
stomata
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Water and minerals are absorbed from soil and are transported to leaves
via tiny vessel-like structures present in roots
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Carbohydrates such as starch and oxygen are the product of
photosynthesis
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Since the autotrophs manufacture their own food, they are called
producers
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Heterotrophic Nutrition
Generally derive energy from plants and animal sources
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e
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Omnivores- feed on both plants and animals e
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bear, rat, man etc
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Mainly of three types—holozoic, parasitic, and saprophytic
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Human digestive system- consists of the long alimentary canal
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Green plants prepare their food by the process of photosynthesis
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The equation for photosynthesis is

Leaves are the sites for the synthesis of food
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Chlorophyll traps solar energy that is used to prepare food from CO2 and water
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Sun is the ultimate source of energy
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Stomata are present on the surface of leaves
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Chlorophyll, sunlight, CO2 and water are essential raw materials for photosynthesis
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The presence of starch in the leaves indicates the occurrence of photosynthesis
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1
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This is done to ensure that the
plant consumes all its reserve food and the leaves do not contain any starch
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Now, expose this plant to bright light
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You will observe that the portion of the leaf covered with black paper does not show any
presence of starch (food)
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Chlorophyll is essential for photosynthesis
Place a variegated plant (i
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a plant which has both green and non-green areas, for e
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croton or

money plant) in a dark room for 2 − 3 days
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Place this plant in sunlight for six hours to allow photosynthesis to take place
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Now, decolourize the leaf using alcohol and dip it in a dilute solution of iodine for a few minutes
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It will be observed that only the green areas of the leaf could photosynthesize
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Transportation in plants
The transportation system in plants moves the energy stored in leaves to
different parts
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Xylem conducts water and minerals obtained from soil (via roots) to the rest of
the plant
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Phloem transports food materials from the leaves to different parts of the plant body
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Transportation
It is a life process where substances synthesised or absorbed in one part of the organism's body
are carried to other parts of the body
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It also helps in moving raw materials absorbed from the roots to various organs
of the plant
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The phloem consists of companion cells, sieve tubes, phloem parenchyma, and fibres
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Excretion in Plants

Plants use a variety of techniques to remove waste materials
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The excess water absorbed from roots is also lost through stomata via transpiration
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are stored in old xylem tissues
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Plant roots also sometimes excrete wastes materials
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Transpiration is the evaporation of water from plants
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Stomata help in gaseous exchange and
evaporation of water
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Amoeba can constantly change its shape with the help of pseudopodia
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When an Amoeba senses its prey, it pushes out its pseudopodia around it and engulfs it
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Digestive juices such as amylase and protease are secreted inside the food vacuole in
an Amoeba
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Amylase breaks down complex carbohydrates into simple sugars while protease breaks
down proteins into simpler substances
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Undigested food is egested using pseudopodia

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