Notes of Chapter- Life Processes
KEY CONCEPTS & GIST OF THE LESSON
v
Life
processes – The processes that are necessary for an organism to stay alive.
Eg. Nutrition, respiration, etc.
v
Criteria
of life- (i) Growth (ii) Movement
v
Nutrition-
The process in which an organism takes in food, utilizes it to get energy, for
growth, repair and maintenance, etc. and excretes the waste materials from the
body.
v
Types of
nutrition
1.
Autotrophic
nutrition (Auto =self: trophos = nourishment)
E.g. Plants, Algae, blue green bacteria.
o
Process – Photosynthesis(Photo=light; Synthesis=
to combine)
o
Raw materials- (i) Carbon dioxide (ii)Water
o
Equation- sunlight
o
6CO2 + 6H2O C6H12O6 +
6O2
Chlorophyll
o
Energy conversion- Light/Solar energy to
Chemical energy
o
Role off Chlorophyll- To trap the sun’s energy
for photosynthesis
o
Factors- (i) Carbon dioxide (ii) Water(iii) Light (iv)
Temperature
o
Events/ Steps of photosynthesis-
(i)
Absorption of light energy by chlorophyll
(ii)
Conversion of light energy to chemical energy
& Splitting of water molecule into Hydrogen & oxygen
(iii)
Reduction of Carbon dioxide to Carbohydrate
o
Gaseous exchange- (i) Gas used- Carbon
dioxide
(ii) By product - Oxygen
o
Source of raw materials-
(i)
Carbon
dioxide –Land plants- Air, Aquatic plants- Water
(ii)
Water & Minerals - Soil
2.
Heterotrophic
nutrition (Hetero =others: trophos =
nourishment) Eg. Animals, plants lacking chlorophyll like fungi.
(a)Saprophytic nutrition: Organisms
feeds on dead decaying plants or animals material. E.g. Fungi, Bacteria
(b) Parasitic
nutrition: Organisms obtain food from the body of another living (host)
o
Endoparasite : Parasite lives inside the body of
the host e.g. tapeworm, roundworm.
o
Exoparasite
: Parasite lives on the body of the
host. E.g. lice, leech.
Note- The parasite benefits while the host is
usually harmed e.g. Cuscutta-plant parasite (amar bel), plasmodium (malarial
parasite).
(c) Holozoic nutrition: Organism (mostly
animals) take in whole food and then digest it into smaller particles with enzyme.
Eg. Amoeba, Paramoecium. Animals, human beings.
o
Steps in
Holozoic nutrition
(i)
Ingestion: taking in of food.
(ii)
Digestion: breaking down of complex food into
simpler, absorbable form.
(iii)
Assimilation: Utilization of digested food from
the body.
(iv)
Egestion: Removing undigested food from the body
o
Nutrition
in human beings
§
Alimentary canal-
Mouth → Oesophagus → Stomach → Small
intestine → Large intestine
§
Important gland/juices
(Refer to figure 6.6 page no.97 of
N.C.E.R.T Text book)
Organ
|
Gland
|
Enzyme/Juice
|
Function
|
Mouth
|
Salivary glands
|
Salivary Amylase
|
Converts starch into sugar
|
Stomach
|
Gastric glands
|
Gastric juice-
(i) Hydrochloric
acid →
(ii) Pepsin →
(iii) Mucus →
|
(a) Kills harmful bacteria that
enters with the
food.
(b) Makes
the medium alkaline
for the action
of Pepsin
Digests proteins
Protects the inner lining of the stomach from the
corrosive action of Hydrochloric acid.
|
Small intestine
|
1) Liver
2) Pancreas
|
(i) Bile juice
→
(ii) Pancreatic
Juice
|
(a) Makes the medium acidic
for the action
of Pancreatic
enzymes.
(b) Breaks down large fat
molecules into
smaller globules
so that enzymes
can act upon
them.
Converts Carbohydrates to glucose
Converts Proteins to Amino acids
Converts Fats into Fatty acids & Glycerol
|
§
Peristaltic movements- Rhythmic contraction of
muscles of the lining of Alimentary canal to push the food forward.
§
Sphincter muscle- Helps in the exit of food from
the stomach.
§
Villi- Small finger like projections on the
walls of-
(v)
Small intestine- To increase the surface area
for the absorption of food.
v
Respiration-
The process by which digested food is broken down with the help of Oxygen to
release energy.
Types of respiration- (i)
Aerobic respiration (ii) Anaerobic
respiration
Aerobic
respiration
|
Anaerobic
respiration
|
1. Takes place in presence of
Oxygen.
2. End products- Carbon
dioxide & Water
3. More energy is released.
4. Takes place in Cytoplasm
& Mitochondria
5. Complete oxidation of glucose takes place.
6. It occurs in most organisms.
7. Equation-
Glucose→ Pyruvate→ CO2
+ H2O + Energy
|
1. Takes place in absence of Oxygen.
2. End
products- Ethanol & Carbon dioxide
3. Less
energy is released.
4. Takes place in only in Cytoplasm.
5.
Incomplete oxidation of glucose takes place.
6. It occurs in certain bacteria,
yeast & certain tissues of higher organisms. E.g. In humans during
vigorous exercise, when the demand for Oxygen is more than the supply, muscle
cells respire anaerobically for some time.
7. Equation-
In Yeast-
Glucose→ Pyruvate→ Ethanol + H2O
+ Energy
In muscle cells -
Glucose→ Pyruvate→ Lactic acid + Energy
|
- Some common features of Respiratory organs-
- (i) Large surface area- for greater rate of diffusion of respiratory gases.
- (ii) Thin permeable walls – to ensure easy diffusion & exchange of gases.
- (iii) Extensive blood supply- Respiratory organs are richly supplied with blood vessels for quick transport of gases.
- Gaseous exchange in plants-
- Process – Diffusion
- Direction of diffusion depends on- (i) Environmental conditions
(ii) Requirement of the plant.
§
Day time- Carbon dioxide given out during
respiration is used for photosynthesis. Therefore only Oxygen is released,
which is a major activity during the day.
§
Night time – Only respiration takes place.
Therefore only Carbon dioxide is released, which is a major activity during the
night.
- Gaseous exchange in animals-
§
Terrestrial animals- take Oxygen from the
atmosphere.
§
Aquatic animals- take Oxygen dissolved in water.
(Oxygen content is low in water, therefore they breathe faster.
- Human Respiratory system-
- External nostrils → Nasal cavity → Trachea→ Bronchi → Bronchioles →Alveoli
§
Rings of cartilage present in the throat ensure
that the trachea (air passage) does not collapse when there is less air in it.
§
Lungs
– (i) Present in the thoracic cavity.
(ii) They are spongy, elastic bags consisting of
Bronchi, Bronchioles and Alveoli
Refer to figure
6.9 page no. 104 of N.C.E.R.T Text book)
- Respiration occurs in two phases-
- (i) External-Breathing, which is a mechanical process. (ii) Internal - Cellular respiration
- Mechanism of breathing – It includes : (i)Inhalation (ii) Exhalation
- Exchange of gases-
§
Unicellular organisms- By Diffusion
§
Animals- (i) As the body size is large,
diffusion alone is not enough.
(ii) Respiratory pigments also required.
§
(iii) Respiratory pigment in human beings
is Haemoglobin, which is present in red blood corpuscles.
§
(iv) It
has very high affinity for Oxygen.
(v) Carbon dioxide is more soluble in water than Oxygen,
so it gets dissolved in blood and is
thus transported.
v
Transportation
- Transportation in human beings-
§
Heart- (Refer to figure 6.10 page no. 106 of
N.C.E.R.T Text book)
(i) It is a muscular organ, which works as a
pump in the circulatory system.
(ii) It is the size of our fist.
(iii) It has two sides, which are separated by a
partition so that the oxygenated and
deoxygenated blood do not get mixed up.
(iv) It has four chambers-
Two upper chambers called Atria.
Two lower chambers called
Ventricles.
Atria
Ventricle
a)
Small in size (volume) a) Large
in size
b) Have thin walls.
b) Have thick walls.
§
Working
of heart-
Left side-
(i) Left atrium relaxes & the Oxygenated blood enters it from
the lungs through the
pulmonary vein.
(ii) Left atrium contracts &
the blood enters the left ventricle
through the valve.
(iii) Left Ventricle contracts and the blood is pumped into the
(iii) Left Ventricle contracts and the blood is pumped into the
largest artery ‘Aorta’ and is
carried to all parts of the body.
Right side- (i) Right atrium relaxes & the deoxygenated
blood from the body enters it through superior and inferior Vena cava.
(ii) Right atrium contracts &
the blood enters the right Ventricle through
the valve.
(iii) Right Ventricle contracts and the blood is pumped into the Pulmonary artery and is carried to
lungs.
§
Valves-
Unidirectional to prevent the backward flow of blood.
§
Pulmonary
vein is the only vein that carries Oxygenated blood.
§
Aorta
is the only artery that carries Deoxygenated blood.
§
Double
circulation in man- because the blood passes through the heart twice in one
complete cycle of the circulation.
§
Higher animals-
E.g., birds, mammals.
(i)
Oxygenated blood & Deoxygenated blood are
completely separate for efficient Oxygen supply.
(ii)
This is
to fulfil higher energy needs and to maintain body temperature (warm
blooded animals).
§
Amphibians & reptiles- have 3 chambered heat
where little mixing of Oxygenated blood
& Deoxygenated blood takes place. Therefore their body temperature varies
with the temperature of the environment. (cold blooded animals)
§
Blood
vessels- (i) Arteries (ii) Veins (iii) Capillaries
Arteries
|
Veins
|
1. Thick walled.
2. Deep seated.
3. Carry blood away
from the heart.
4. Carry Oxygenated
blood.
5. Valves absent.
|
1. Thin walled.
2.
Superficial.
3. Carry blood to
the heart.
4. Carry Deoxygenated blood.
5. Valves present
|
§
Capillaries- (i) Form the connection between arteries &
veins.
(ii)
Walls are one cell thick only for easy exchange of
blood.
§
Blood-
(i) It is a fluid connective tissue.
ii)Components-
(1) Fluid medium- Plasma transports food, Oxygen,
Carbon dioxide, Nitrogenous wastes, etc.
(2) Red blood corpuscles-
transports oxygen with the help of haemoglobin
protein.
(3) White blood corpuscles- fight
against infections/ defence mechanism of the
body.
(4)
Platelets – Plug the leaks of arteries and veins by clotting the blood.
Functions
of blood- (i) Transport of respiratory gases.
(ii) Transport of nutrients.
(iii) Transport of
waste products.
(iv) Defence against infection
§
Lymph- Extracellular fluid similar to plasma but
colourless with lesser protein.
§
Function of lymph- (i) Transportation of digested & absorbed
fats from
the
small intestine.
(ii) Drains excess fluid from the
intercellular spaces
back in the blood.
- Transportation in plants-
§
Plants need less energy needs- because they do
not move and therefore have a slow transport system
§
Transport of water-
(i)
Takes place by xylem tissue present in roots,
stem, leaves and is therefore interconnected.
(ii)
Root cells take up ions from the soil, which
creates a concentration difference between root and soil. Column of water
therefore rises upwards.
§
In very tall plants- transpiration creates a
suction pressure, which pulls the water upwards.
§
Transpiration
is loss of water in form of water vapors from stomata present on leaf surface
§
Importance of transpiration-
(i)
Helps in upward movement of water in plants.
(ii)
It regulates the temperature in plants.
§
Transport
of food-
(i)
Takes place by phloem tissue.
(ii)
Movement of prepared food in plants is called translocation.
.v
Excretion-
The biological process of removal of harmful metabolic wastes in living
organisms.
- Excretion in human beings-
(Refer to figure
6.13 page no. 110 of N.C.E.R.T Text
book)
§
Organs of
excretory system- (i) Kidneys
(iii) Urinary bladder
(ii) Ureters (iv) Urethra
§
Kidneys-
(i)
Two in number
(ii)
Bean shaped
(iii)
Present in abdomen on either side of the
backbone
(iv)
Basic unit is nephron.
.a. Glomerulus-
Group of capillaries (cluster) present in Bowman’s capsule to receive
blood from renal artery and filters it.
b. Bowman's Capsule- cup shaped structure which contains glomerulus.
c. Renal tubule- is long and reabsorbs vital
nutrients like glucose, amino acids, salts, urea and water.
Functions of Kidneys- (a) Filtration & removal
of Nitrogenous wastes. (b)
Reabsorption of vital nutrients
§
Ureters- Transport the urine formed in the
kidneys to the urinary bladder.
§
Urinary bladder- Muscular bag like structure to
store urine.
§
Urethra- Helps in removal of urine when the
Urinary bladder is full.
§
Artificial kidney- Principle: Dialysis
- Excretion in plants-
v
Important
diagrams-
1.
Open & close stomata
2.
Steps of nutrition in Amoeba
3.
Alimentary canal of human beings/ Digestive
system of human beings
4.
Respiratory system of human beings
5.
Structure of heart.
6.
Excretory system of human beings
7.
Structure of nephron
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