LIFE
PROCESSES
Life
Processes – The important processes carried out by
the living organism to maintain and sustain life are called ‘Life Processes’.
Eg. Nutrition, Respiration, transportation, Excretion
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Unicellular
Organisms
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Multicellular
Organisms
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In unicellular organisms entire body is
in contact with the environment. Therefore the exchange of gases and other
substances takes place across the cell membrane by the way of simple
Diffusion.
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In Multicellular all the cells are not
in direct contact with the environment.
So, simple diffusion doesn’t meet the
requirement of the cells.
We have specialised tissues and organs
for different life processes.
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NUTRITION
The process of obtaining, consuming and utilizing food
by the living organism is defined as Nutrition.
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Autotrophs
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Heterotrophs
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The organisms which prepare their own
food using simple inorganic substances like carbon dioxide and water are
called as Autotrophs.
Eg. Green plants
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The organisms which cannot prepare their
own food and depend either directly or indirectly on Autotrophs to obtain
complex organic substances for nutrition are called as Heterotrophs.
Eg. Animals
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AUTOTROPHIC
NUTRITION
Photosynthesis
– This is the process in which plants prepare their food using carbon dioxide
and water in presence of sunlight and chlorophyll and is converted to
carbohydrates.
6CO2 + 12H2O ------------------------Ã
C6H12O6
+ 6O2 + 6H2O
Steps
-
Light energy is absorbed
by the chlorophyll
- Light energy is converted
to Chemical energy
- Water molecule splits
into hydrogen and oxygen
-
Carbon dioxide is reduced
to carbohydrates
- Chlorophyll helps to
capture the light energy
- Carbon dioxide enters the
leaf through small openings called ‘Stomata’
- The opening and closing
of stomata is controlled by the guard cells.
HETEROTROPHIC
NUTRITION
In this mode of nutrition organism obtain the food the
outside source.
·
In amoeba food is captured at any point along the cell membrane
(pseudopodia)
·
In paramecium food enter the body through one fixed point at cell
membrane.
·
Saprophytes
– Organisms obtain food from dead and decaying matter. Eg. fungi
·
Parasites
– Organisms depends on the host for the nutrition. Eg. Leech, worms
Holozoic
nutrition – In this the whole food consumed is
broken down and digested with the help of enzymes. Eg. Human beings
Digestion in human beings takes place along the
alimentary canal. (Mouth, oesophagus, food pipe, stomach, duodenum, small
intestine, large intestine, anus)
Enzymes
– These are different catalyst which helps to convert the convert the complex
food molecules to the simple absorbable form.
Steps
in digestion
1) Mouth
– In mouth teeth break the food in smaller particles. Saliva secreted by salivary glands mixes with the food and
makes it soft. This soft ball called ‘Bolus’ is pushed towards the oesophagus.
Epiglottis,
a cartilaginous flap closes the pharynx (wind pipe) while the food passes
through oesophagus.
Salivary gland Ã
amylase à starch to maltose
2) Stomach
– stomach expands when food enters into it. Gastric glands present in
the inner lining of stomach secrets few digestive enzymes and helps in further
digestion of food.
Hydrochloric
acid à destroys microbes
Mucus
Ã
protects the inner lining of the stomach from the action of acid.
Pepsin
Ã
Proteins to polypeptides (chain of amino acids)
Rennin
à Milk
proteins to curd
In stomach the food is converted to semi
liquid form called as ‘Chyme’.
Food is passed to the small intestine in
small amounts. This is regulated by the “Sphincter Muscles”.
3) Duodenum
– This is the beginning part the small intestine. In this portion the Bile Juice from the Liver and Pancreatic Juice from the Pancreas add to the food.
Bile juice Ã
Emulsify the fats
Pancreatic juice trypsin - digests proteins
Lipase - fats to simple fats
4) Small Intestine
– This is the longest part of alimentary canal. It is fitted in a compact space
in coiled manner.
Walls of small intestine secrets
intestinal juice, which contains different enzymes that helps in final
digestion of food.
Proteins - Amino Acids
Carbohydrates - glucose
Fats - Fatty acids and glycerol
The walls of small intestine have numerous
finger like projections called “Villi”.
This increases the surface area for absorption of digested food. Villi are rich
in blood vessels and absorb the digested food. This is carried to every cell of
the body and utilized for obtaining energy, building new tissues and repair of
old tissues.
5) Large Intestine
– The remaining food material passes to the large intestine. The Villi here
absorbs the water.
6) Anus
– This is the exit of the alimentary canal. The rest of the material is thrown
off the body through anus. This exit is controlled by Anal Sphincter.
Peristalsis
– This is the contraction and relaxation movement of the muscles of the entire
alimentary canal. This helps the food to move forward in the digestive track.
RESPIRATION
This is the process in which the organic molecules are
stepwise oxidised to release energy.
Glucose molecule (6 carbon atoms) breaks to form
three-carbon molecule called Pyruvate.
Types of respiration
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Aerobic
respiration
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Anaerobic
Respiration
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1) This
takes place in presence of oxygen
2) Pyruvate
breaks to carbon dioxide and water.
3) Large
amount of energy is released
4) This
takes place in higher organisms.
Human beings
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1) This
takes place in absence of oxygen.
2) Pyruvate
is converted to Ethanol and carbon dioxide.
This takes place during fermentation.
3) Small
amount of energy is released
4) This
takes place in lower organisms.
Yeast, bacteria
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Sometimes, in our muscles
cells, due to the lack of oxygen, the Pyruvate molecules break to form Lactic
acid. This activity causes cramps in muscles.
The energy released in cellular respiration is used to
synthesize ATP molecule.
This serves as a fuel for other cellular activities.
Plants
– In plants exchange of gases take place by diffusion.
During day time, CO2 released during
respiration is utilized for photosynthesis and O2 is released.
Therefore oxygen release is the major event.
At night, there is no photosynthesis and so CO2
elimination is major event.
Aquatic organisms
use dissolved oxygen for respiration. As the amount of dissolved oxygen is
comparatively low the rate of breathing is faster in aquatic organisms.
Gills
are the respiratory organs of fish.
Respiration
in Human Beings
·
Respiratory system
includes nose, pharynx, trachea, bronchi, bronchioles, alveoli and lungs.
·
Air enters the
respiratory system through nostrils. Fines hairs and mucous in the nostrils
filters the air. The air becomes moist and warm according to the body
temperature
·
The air passes through
the throat, trachea and then to the bronchi which leads to each lung. The ‘C’
shaped cartilaginous rings keeps the trachea open, prevents it from collapsing,
and this ensures the continuous flow of air.
·
The bronchi are further
branched in to bronchioles and terminate with the balloon like structures
called ‘Alveoli’. Alveoli contain
the networks of capillaries. This increases the surface area for the exchange
of gases.
·
The Haemoglobin, a
pigment present in RBC take up the oxygen and carry it to the tissues all over
the body.
·
Carbon dioxide is
transported in the dissolved form in our blood.
TRANSPORTATION
Transport system in man
1. Blood
2. Blood
vessels
3. Heart
1) Blood
– Blood is the fluid connective tissue which carries essential gases and other
required materials to each and every cell of the body. This consists of
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Plasma
·
Red Blood Corpuscles
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White Blood Corpuscles
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Platelets
2)
Blood
vessels – Arteries, Veins and Capillaries
·
Arteries
are blood vessels which carries oxygenated blood from heart to different parts
of the body. Blood emerges from the heart under high pressure. Therefore,
arteries have thick and elastic walls.
·
Veins
– Veins carry de-oxygenated blood from different parts to the body to the
heart. Veins do not need thick walls as the blood is no longer under pressure.
Valves are present in veins to ensure the
flow of the blood only in one direction.
·
Capillaries –
These are very thin blood vessels (one celled thick) which help in exchange of
material between cells and blood.
3)
Heart
Size – Fist size
Shape – Conical
Position – Obliquely placed little towards
left in the thoracic cavity between the lungs.
The Heart has four chambers – upper
chambers ‘Atrium’ and lower chambers ‘Ventricles’
The pressure required to maintain the flow
of the blood is created by contraction and relaxation of the muscles. Atriums
and ventricles contracts and relax simultaneously.
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Action
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Change in Right
Side
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Change in left
side
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Atriums Relax
(Ventricles
Contract)
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De-oxygenated
blood from all parts of the body flows to right Atrium. (through superior and
inferior venacave)
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Oxygenated blood
from lungs comes to left Atrium
(through
pulmonary vein)
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Atriums Contract
(Ventricles
relax)
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De-oxygenated
blood from right Atrium flows to Right Ventricle. (through tricuspid valve)
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Oxygenated blood
from left Atrium flows to left Ventricle. (through bicuspid valve)
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Ventricles
Contract
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De-oxygenated
blood from right Ventricle goes to lungs (through pulmonary artery)
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Oxygenated blood
from left Ventricle goes out of heart through Aorta.
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Important
Terms
·
Pericardium
– This is the double layered muscular sac in which heart is placed.
·
Pericardial
Fluid – This is the fluid present between the
layers of Pericardium.
This protects the heart from mechanical
shocks and friction.
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Atriums
– Upper chambers of heart
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Ventricles
– Lower chambers of heart
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Septum
– Muscular layer that separates the right and left portion of heart.
This is
useful to prevent mixing of oxygenated and de-oxygenated blood.
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Tricuspid
Valve – This is the valve present between right
Atrium and right Ventricle.
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Bicuspid
Valve – This is the valve present between left
Atrium and left Ventricle.
(Valves prevents the backward flow of the
blood)
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Coronary
Artery – This is the artery that supplies
oxygenated blood to the muscles of heart.
·
Coronary
Sinus – This is the vein which carries
deoxygenated blood from the muscles of heart to the right Atrium.
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Semi
lunar valves – These are the valves present at
the beginning of the arteries to prevent the backward flow of the blood.
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Systole
– Contraction of heart muscles
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Diastole
– Relaxation of heart muscles
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Heart
Beat – One Systole + One Diastole = One Heart
Beat
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Stethoscope
– Instrument used to measure heart beat. (72 beats/minute)
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Sphygmomanometer
– Instrument used to measure blood pressure.
(80/120
mm Hg)
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Blood
Pressure – The force that blood exerts against the
wall of the blood vessel is called as ‘Blood Pressure’.
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Pulse
– Relaxation and Contraction of the artery forms a wave like movement called
‘Pulse’.
Double
Circulation
(Blood goes to the heart twice during each cycle)
1) Pulmonary
Circulation – Circulation of blood from heart to
lungs and lungs to heart.
2) Systematic
Circulation – Circulation of blood from heart to
tissues of body and body to heart.
·
Significance – This keeps
oxygenated blood separate from the de-oxygenated blood.
Amphibians and Reptiles
have three-chambered heart. They can tolerate mixing of oxygenated and
de-oxygenated blood as their energy requirement is less compared to that of
mammals.
Fishes
have two chambered heart. Blood is pumped towards gills and from Gills the
oxygenated blood is directly supplied to the body of the fish.
Platelets
– Platelets initiates blood clotting. If there is leakage in any blood vessels
these platelets helps to plug these leaks.
Lymph
– Some of the plasma, proteins and blood cells escape through the pores of the
blood vessels into the intercellular spaces of the tissues. This colourless
fluid is called as Tissue fluid or lymph.
Transportation
in Plants
Two conducting tissues of plants – Xylem and Phloem
·
Xylem conducts water and
mineral salts from soil to the leaves.
·
Phloem conducts the
products of photosynthesis to the other parts of the plant.
This is called as Translocation.
The food is mostly stored in roots, fruits and seeds.
Transpiration
– The loss of water molecules in the form of vapour from the aerial parts is
known as ‘Transpiration’. This is fast during the day time as the stomata are
open for exchange of gases.
This helps for the absorption of water and mineral
salts from roots to leaves.
This also helps for the temperature regulation.
EXCRETION
The process by which the metabolic wastes are
eliminated from the body is called as ‘Excretion’.
Excretion
in Human Beings
This includes a pair of Kidneys, a pair of Ureters,
Urinary Bladder and Urethra.
Kidney
Position – located at the back of abdominal cavity one
on the either side of the backbone
Hilum
– depression point at each kidney
Renal capsule
– tough connective tissue capsules covering kidneys.
Nephron
– structural and functional unit of kidneys
Bowman’s capsule
– cup shaped structure at the beginning of nephron
Glomerulus
– network of capillaries formed in the Bowman’s capsule.
Urine
formation
·
Blood vessel entering the
Bowman’s capsule breaks into tough network of capillaries called ‘Glomerulus’.
·
The pressure created
enables the filtration of the blood. This filtrate contains nitrogenous wastes,
sodium and potassium bicarbonates along with water, glucose, vitamins and amino
acids. This passes to the Henle’s loop.
·
Surrounding capillaries
absorb the essential nutrients from the filtrate.
·
Lastly, potassium,
ammonium salts, hydrogen ions and uric acid is secreted in the filtrate. This
combines with the urea, nitrogenous wastes and excess of salts and forms urine.
·
The urine formed in the
kidneys passes through the ‘Ureters’ and finally is collected in the ‘Urinary
bladder’.
·
The pressure of the
expanded bladder leads to the urge to pass out the urine through ‘Urethra’.
Excretion
in plants
Oxygen is given out as the bi-product of
photosynthesis.
Excess of water is given out by the way of
‘Transpiration’.
There’s no specialised tissue for excretion.
Excretory wastes are stored in some of the parts like
roots, barks and leaves. Later the plants get rid of these parts naturally.
In some cases it is stored as resins and gums.
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