Life processes class 10 notes chapter 6
WHAT ARE LIFE PROCESSES?
- The maintenance functions of living organisms must go on even when
they are not doing anything particular
- The processes which together perform this maintenance job are
life processes
- Nutrition, respiration, circulation, excretion are examples of essential life processe
- In case of unicellular organisms, all these processes like taking in food, exchange of gases or
removal of wastesare carried out by that single cell while in multi-cellular organisms, various
body parts have specialised in the functions they perform.
NUTRITION: The process of providing or obtaining the food necessary
for health and growth
Modes of nutrition: There are two main modes of nutrition
i)
Autotrophic
ii) Heterotrophic.
Autotrophic Nutrition: Some organisms use simple
food material obtained from inorganic sources in the form of carbon
dioxide and water.
Photosynthesis:
- It is the process by which autotrophs take
in substances from the outside and convert them into stored forms of
energy
- This material is taken in the form of carbon dioxide and water
which is converted into carbohydrates in the presence of sunlight and
chlorophyll.
- Carbohydrates are utilised for providing energy to the plant
Events occur during this process:
- Absorption of light energy by
chlorophyll.
- Conversion of light energy to chemical
energy and splitting of water molecules
into hydrogen and oxygen.
- Reduction of carbon dioxide to
carbohydrates.
chlorophyll: These green dots are cell organelles called
chloroplasts which contain chlorophyll
Stomata:
- The tiny pores present on the
surface of the leaves help exchange of gases
- large amounts of water can also be lost
through these stomata
- The opening and closing of the
pore is a function of the guard cells.
Heterotrophic Nutrition: Heterotrophic nutrition is a type of nutrition
in which organisms depend upon other organisms
Saprophytic Nutrition: organisms
break-down the food material outside the body and then absorb it. Examples are fungi like bread
moulds, yeast and mushrooms.
Parasitic Nutrition: organisms derive nutrition from plants or
animals without killing them like cuscuta (amar-bel), orchids, ticks,
Nutrition in Amoeba:

i) The mode of nutrition in Amoeba is holozoic
ii)
Amoeba takes in food using
temporary finger-like extensions called pseudopodia and fuse over
the food particle forming a food-vacuole
iii) Inside the food vacuole, complex substances are
broken down into simpler ones and diffuse into the cytoplasm.
Nutrition Paramoecium,
i) The mode of nutrition in Paramoecium, is
holozoic
ii) they have cilia that help them to cover the entire surface food through the oral
groove.
iii) And forming a food-vacuole and digestion take place s
Nutrition in Human Beings:
i) humans are omnivores they eat
various types of food
ii) There are five stages in human nutrition; Ingestion, Digestion,
Absorption, Assimilation and Egestion.
Digestion process

- first we take food in mouth and starting crushing the food with our teeths
- A fluid called saliva secreted by the salivary glands
- The food is mixed thoroughly with saliva and moved around the mouth while chewing by the
muscular tongue
- Saliva has to be broken into smaller molecules with the help of biological catalysts called
enzymes
- This enzyme called salivary amylase that breaks down complex molecule called starch to give
sugar
- The lining of canal has muscles that push the food forward
- , the food is taken to the stomach through the food-pipe or oesophagus
- The muscular walls of the stomach help in mixing the food
- gastric glands present in the wall of the stomach help for digestion
- These release hydrochloric acid, a protein digesting enzyme called pepsin, and mucus.
- The hydrochloric acid creates an acidic medium which facilitates the action of the enzyme pepsin
- The mucus protects the inner lining of the stomach from the action of the acid under normal
conditions.
- a sphincter muscle help in releasing of food from the stomach into the small intestine
- small intestine is the longest part of the alimentary canal
- The length of the small intestine differs in various animals depending on the food they eat.
- Note Herbivores eating grass need a longer small intestine to
allow the cellulose to be digested. Meat is easier
to digest, hence carnivores like tigers have a shorter small intestine.
- The small intestine is the site of the complete digestion of carbohydrates, proteins and fats.
- Bile juice from the liver accomplishes this in addition to acting on fats.
- Fats are present in the intestine in the form of large globules which makes it difficult for
enzymes to act on them So, Bile salts break them down into
smaller globules increasing the efficiency of enzyme action.
- The pancreas secretes pancreatic juice which contains enzymes like trypsin for digesting
proteins and lipase for breaking down emulsified fats
- Small intestine contain glands which secrete intestinal juice.
- The enzymes present in it finally convert the proteins to amino acids, complex carbohydrates
into glucose and fats into fatty acids and glycerol.
- The internal surface of the small intestine is folded into finger-like projections called villi.
- villi which increase the surface area for absorption.
- The unabsorbed food is sent into the large intestine where more villi absorb water from this
material
- The rest of the material is removed from the body via the anus.
RESPIRATION:
i)Respiration means the exchange of gases.
ii)Breaking down of glucose into pyruvate: This happens in the cytoplasm. Glucose molecule is broken
down into pyruvic acid. Glucose molecule is composed of 6 carbon atoms, while pyruvic acid is
composed of 3 carbon atoms.
iii)Fate of Pyruvic Acid: Further breaking down of pyruvic acid takes place in mitochondria and the
molecules formed depend on the type of respiration in a particular organism. Respiration is of two
types, viz. aerobic respiration and anaerobic respiration.
Respiration involves
Gaseous exchange: Intake of oxygen from the atmosphere and release of CO2 →
Breathing.
Breakdown of simple food in order to release energy inside the cell → Cellular respiration
4)During the process of respiration, complex organic compounds such as glucose
are broken down to provide energy in the form of ATP. ATP is used to provide
energy for other reactions in the cell.
Aerobic respiration: Breakdown of pyruvate using oxygen takes place in
the mitochondria. This process breaks up the three-carbon pyruvate molecule to give three molecules
of carbon dioxide and water is called aerobic
respiration
Anaerobic respiration:: The pyruvate may be converted into ethanol and
carbon dioxide. This process takes place in yeast during fermentation. Since this process takes
place in the absence of air (oxygen), it is called anaerobic respiration
- Different organisms use different methods for the intake of oxygen and expulsion of carbon
dioxide.
- plants exchange gases through stomata,
- Fishes take in water through their mouths and force it past the gills where the dissolved
oxygen is taken up by blood.
- the rate of breathing in aquatic organisms is much faster than that seen in terrestrial
organisms
Respiration in human beings:
- The air passing through the nostrils is filtered by fine hairs that line the passage
- the air passes through the throat and into the
lungs
- Rings of cartilage are present in the throat. These ensure that the air-passage does not
collapse.
- The balloon-like structures in lungs which are called alveoli
- The alveoli provide a surface where the exchange of gases can
take place.
- the oxygen in the alveolar air is taken up by blood in the alveolar blood vessels to be
transported to all the cells in the body
- The blood brings carbon dioxide from the rest of the body for release into the alveoli,
- Note: the lungs always contain a residual volume of air so that
there is sufficient time for oxygen to be absorbed and for the carbon
dioxide to be released
- the respiratory pigment is haemoglobin which carry oxygen
TRANSPORTATION :
Transportation in Human Beings: Blood consists of a fluid medium
called plasma which transports food, carbon
dioxide and nitrogenous wastes in dissolved form
Our pump — the heart:
- The heart is a muscular organ which is as big as our fist
- the heart has four chambers
- the heart has different chambers to prevent the oxygen-rich blood from mixing with the blood
containing carbon dioxid
- the oxygenated blood from the lungs has to be brought back to the heart
- This oxygen-rich blood is then pumped to the rest of the body.
process:
- Oxygen-rich blood from the lungs comes the left atrium.The left atrium relaxes and collecting
this blood.
- after blood is transferred to left ventricle
- When the muscular left ventricle contracts in its turn, the blood is pumped out to the body.
- De-oxygenated blood comes from the body to the right atrium,
- transfers blood to the right ventricle, which pumps it to the lungs for oxygenation.
- ventricles have thicker muscular walls than the atria
- Valves: Valves ensure that blood does not flow backwards when
the atria or ventricles contract.
Double Circulation
- In the human body, blood circulates through the heart twice.>/li>
- Once it goes through the heart during pulmonary circulation and second time during systemic
circulation.
- Hence, circulation in human beings is called double circulation
Blood pressure:
- The force that blood exerts against the wall of a vessel is called blood pressure.
- Blood pressure is measured with an instrument called sphygmomanometer.
- The pressure of blood inside the artery during ventricular systole (contraction) is called
systolic pressure
- pressure in artery during ventricular diastole (relaxation) is called diastolic pressure
- The normal
systolic pressure is about 120 mm of Hg and diastolic pressure is 80 mm of Hg.
blood vessels:
-
Blood vessels carry blood throughout the body
- There three types of blood vessels; arteries, veins and blood capillaries.
- Arteries are the vessels which carry blood away from the heart to various organs of the body and
veins carry deoxygenated blood.
- The smallest vessels have walls which are one-cell thick and are called
capillaries. Exchange of material between the blood and surrounding
cells takes place across this thin wall.
Platelets: The platelet cells which circulate around the body and plug
these leaks of blood by helping to clot the blood at
these points of injury.
Lymph: Atype of fluid also involved in transportation. This is
called lymph or tissue fluid..Lymph is to carry absorbed digested fat from intestine and it also
drains excess fluid from extra cellular space back into the blood.
Transportation in Plants:
- The other kinds of raw materials needed for building plant bodies will also have to be taken up
separately.
- Food and water transportation takes place separately in plants
- xylem moves water
and minerals obtained from the soil
- phloem transports food to other parts of the plant.
Transport of water:
Xylem tissue,:
- Xylem tissue is made up tracheids, vessels, xylem fibres and xylem parenchyma.
- xylem tissue is a continuous system of water-conducting
channels reaching all parts of the plant.
- Xylem creating a column
of water that is steadily pushed upwards
- Transpiration: The loss of water in the form of vapour from the
aerial parts of the plant is
known as transpiration
Transport of food and other substances:
Phloem:
- pholem tissue is made of Sieve tubes, companion cells, phloem fibres, and phloem parenchyma
cells .
- The phloem is help for translocation of nutrients and sugar like carbohydrates, produced by the
leaves to other of the plant .
- Direction of pholem in both upward and downward directions.
- the phloem
transports amino acids and other substances.
- Translocation:
- This transport of soluble products of photosynthesis
is called translocation
- it occurs in the part of the vascular tissue
known as phloem
- s. The translocation of food and other substances takes
place in the sieve tubes
- Material like sucrose is transferred into phloem tissue using
energy from ATP.
- This increases the osmotic pressure of the tissue
causing water to move into it
EXCRETION:

The biological
process involved in the removal of these harmful metabolic wastes from
the body is called excretion.
In unicellular organisms remove these wastes by simple
diffusion from the body surface into the surrounding
water
Excretion in Human Beings:
- The excretory system of human beings includes a pair of kidneys, a pair of ureters, a urinary
bladder and a urethra
- Urine
produced in the kidneys passes through the ureters
into the urinary bladder where it is stored until it is
released through the urethra.
- Kidneys:
- Kidneys are located in the
abdomen, one on either side of the backbone
- They are helping the filtration units of the human bod
- it consiste a cluster of very thin-walled blood
capillaries
- each capillaries collecting the filtered urine
- nephrons:

kidney has
large numbers of these filtration units called nephrons
- They filtrate, such as glucose, amino acids, salts and a major
amount of water and re-absorbed
Excretion in Plant:
- Plants use different method for excretion than animals
- Oxygen can be thought of as a waste product during photosynthesis
- Excess water by transpiration
- Other waste products are stored as resins and gums, especially in old xylem