INTRODUCTION
Have you
ever wondered how we know whether something is alive or not?
A dog
running on the road, a bird flying in the sky, or a person speaking clearly
show signs of life. But even when a person is sleeping or a plant appears
still, they are still alive. This is because countless activities continue
inside living organisms every second. These internal activities are known as life
processes.
Living
organisms constantly:
- Obtain
food
- Release
energy
- Transport
materials
- Remove
wastes
- Repair
damaged cells
Without
these processes, life cannot continue.
WHAT ARE
LIFE PROCESSES?
The basic
activities that maintain life are called life processes.
Examples:
- Nutrition
- Respiration
- Transportation
- Excretion
Even when we
are resting, sleeping, or sitting quietly, these processes continue inside our
body to maintain proper functioning.
WHY ARE LIFE
PROCESSES IMPORTANT?
The body of
every organism is made up of highly organised structures such as:
- Cells
- Tissues
- Organs
- Organ
systems
Environmental
conditions continuously damage these structures. Therefore, living organisms
must constantly:
- Repair
themselves
- Maintain
internal balance
- Produce
energy
For this
reason, life processes are essential for survival.
ENERGY
REQUIREMENT IN LIVING ORGANISMS
All life
processes require energy.
This energy
comes from:
Food
Food
provides:
- Energy
- Raw
materials for growth
- Materials
for repair of tissues
Since most
living organisms are carbon-based, food also mainly contains carbon compounds.
MAIN LIFE
PROCESSES
|
Life Process |
Main Function |
|
Nutrition |
Obtaining
and utilising food |
|
Respiration |
Releasing
energy from food |
|
Transportation |
Movement
of substances |
|
Excretion |
Removal of
waste products |
DIFFERENCE
BETWEEN UNICELLULAR AND MULTICELLULAR ORGANISMS
In
Unicellular Organisms
Example:
- Amoeba
- Paramoecium
Characteristics:
- Entire
body surface exchanges gases
- Food
enters directly through surface
- Wastes
diffuse out easily
Simple
diffusion is enough because the organism is very small.
In
Multicellular Organisms
Example:
- Humans
- Animals
- Plants
Characteristics:
- Body is
large and complex
- All
cells are not directly exposed to environment
- Special
organs and tissues are needed
Therefore:
- Digestive
system
- Respiratory
system
- Circulatory
system
- Excretory
system
become
necessary.
5.2
NUTRITION
Nutrition is
the process by which organisms obtain food and use it for:
- Energy
- Growth
- Repair
- Maintenance
TYPES OF
NUTRITION
There are
two major types of nutrition:
- Autotrophic
Nutrition
- Heterotrophic
Nutrition
1.
AUTOTROPHIC NUTRITION
The mode of
nutrition in which organisms prepare their own food is called autotrophic
nutrition.
Organisms
showing this mode are called:
Autotrophs
Examples:
- Green
plants
- Algae
- Some
bacteria
Plants
prepare food using:
- Carbon
dioxide
- Water
- Sunlight
- Chlorophyll
PHOTOSYNTHESIS
The process
by which green plants prepare food in the presence of sunlight and chlorophyll
is called photosynthesis.
Chemical
Equation
EVENTS OF
PHOTOSYNTHESIS
The
following steps occur during photosynthesis:
- Chlorophyll
absorbs sunlight
- Light
energy converts into chemical energy
- Water
molecules split into hydrogen and oxygen
- Carbon
dioxide reduces to carbohydrates
CHLOROPLAST
Chloroplasts
are green cell organelles containing chlorophyll.
Function
They trap
sunlight required for photosynthesis.
STARCH –
STORED FOOD
The glucose
prepared during photosynthesis is converted into:
Starch
Starch acts
as reserve food in plants.
Similar to
this, humans store excess glucose as:
Glycogen
ACTIVITY 5.1
– CHLOROPHYLL IS NECESSARY FOR PHOTOSYNTHESIS
Experiment
Using Variegated Leaf
Steps
- Take a
potted plant with variegated leaves.
- Keep it
in darkness for 3 days.
- Place
in sunlight for 6 hours.
- Boil
leaf in water.
- Heat
leaf in alcohol to remove chlorophyll.
- Add
iodine solution.
Observation
- Green
portions become blue-black.
- Non-green
portions remain brown.
Conclusion
Starch is
formed only in green parts containing chlorophyll.
STOMATA
Tiny pores
present on the surface of leaves are called stomata.
Functions
- Exchange
of gases
- Loss of
water vapour during transpiration
GUARD CELLS
Guard cells
regulate opening and closing of stomata.
Opening of
Stomata
Guard cells
absorb water and swell.
Closing of
Stomata
Guard cells
lose water and shrink.
ACTIVITY 5.2
– CARBON DIOXIDE IS ESSENTIAL FOR PHOTOSYNTHESIS
Experiment
Using Potassium Hydroxide (KOH)
Principle
KOH absorbs
carbon dioxide.
Observation
Leaf kept
without carbon dioxide does not show starch formation.
Conclusion
Carbon
dioxide is essential for photosynthesis.
RAW
MATERIALS REQUIRED FOR PHOTOSYNTHESIS
|
Material |
Source |
|
Carbon
dioxide |
Atmosphere |
|
Water |
Soil |
|
Sunlight |
Sun |
|
Chlorophyll |
Chloroplast |
ROLE OF
NITROGEN IN PLANTS
Nitrogen is
essential for:
- Protein
synthesis
- Growth
Plants
absorb nitrogen in the form of:
- Nitrates
- Nitrites
prepared by
bacteria from atmospheric nitrogen.
2.
HETEROTROPHIC NUTRITION
The mode of
nutrition in which organisms depend on other organisms for food is called
heterotrophic nutrition.
Examples:
- Humans
- Animals
- Fungi
TYPES OF
HETEROTROPHIC NUTRITION
|
Type |
Example |
|
Saprophytic |
Mushroom,
Bread mould |
|
Parasitic |
Cuscuta,
Tapeworm |
|
Holozoic |
Human
beings |
SAPROPHYTIC
NUTRITION
Organisms
obtain food from dead and decaying matter.
Examples:
- Yeast
- Mushroom
- Bread
mould
They digest
food outside the body and absorb nutrients.
PARASITIC
NUTRITION
Organisms
derive food from living hosts without killing them.
Examples:
- Cuscuta
(Amarbel)
- Ticks
- Lice
- Leech
- Tapeworm
HOLOZOIC
NUTRITION
Organisms:
- Ingest
food
- Digest
food
- Absorb
nutrients
- Remove
wastes
Example:
Human beings
NUTRITION IN
AMOEBA
Amoeba uses
finger-like projections called:
Pseudopodia
to capture
food.
Steps of
Nutrition in Amoeba
- Ingestion
- Formation
of food vacuole
- Digestion
- Absorption
- Egestion
NUTRITION IN
HUMAN BEINGS
The human
digestive system consists of:
- Mouth
- Oesophagus
- Stomach
- Small
intestine
- Large
intestine
- Rectum
- Anus
The food
passes through a long tube called:
Alimentary
Canal
1. MOUTH
Food is:
- Chewed
by teeth
- Mixed
with saliva
SALIVA
Saliva
contains enzyme:
Salivary
Amylase
which
digests starch into sugars.
Reaction
ACTIVITY 5.3
– ACTION OF SALIVA ON STARCH
Observation
Test tube
containing saliva does not turn blue-black with iodine.
Conclusion
Saliva
digests starch.
PERISTALTIC
MOVEMENTS
Rhythmic
wave-like contractions of alimentary canal muscles that push food forward are
called peristaltic movements.
2.
OESOPHAGUS
Also called:
Food Pipe
Carries food
from mouth to stomach.
3. STOMACH
The stomach
secretes:
- Hydrochloric
acid (HCl)
- Pepsin
- Mucus
FUNCTIONS OF
HCl
- Creates
acidic medium
- Activates
pepsin
- Kills
harmful bacteria
PEPSIN
Digests
proteins into simpler substances.
Reaction
ROLE OF
MUCUS
Protects
stomach lining from acid.
ACIDITY
Excess acid
causes:
- Burning
sensation
- Indigestion
- Stomach
irritation
4. SMALL
INTESTINE
Longest part
of alimentary canal.
Main
Functions
- Complete
digestion
- Absorption
of nutrients
ROLE OF BILE
JUICE
Secreted by:
Liver
Functions:
- Makes
food alkaline
- Breaks
fats into smaller droplets
This process
is called:
Emulsification
ROLE OF
PANCREAS
Pancreas
secretes pancreatic juice containing:
|
Enzyme |
Function |
|
Trypsin |
Digests
proteins |
|
Lipase |
Digests
fats |
INTESTINAL
JUICE
Converts:
- Proteins
→ Amino acids
- Carbohydrates
→ Glucose
- Fats →
Fatty acids + Glycerol
VILLI
Finger-like
projections present in small intestine.
Functions
- Increase
surface area
- Absorb
digested food
Each villus
contains blood vessels for transporting absorbed nutrients.
5. LARGE
INTESTINE
Functions:
- Absorbs
water
- Forms
faeces
Waste is
removed through anus.
DENTAL
CARIES
Tooth decay
caused by acids produced by bacteria acting on sugars.
Prevention
- Brushing
teeth regularly
- Maintaining
oral hygiene
5.3
RESPIRATION
Respiration
is the process of releasing energy from food.
RESPIRATION
EQUATION
BREAKDOWN OF
GLUCOSE
Glucose
first breaks into pyruvate in cytoplasm.
TYPES OF
RESPIRATION
|
Type |
Oxygen Requirement |
|
Aerobic
Respiration |
Requires
oxygen |
|
Anaerobic
Respiration |
Does not
require oxygen |
ANAEROBIC
RESPIRATION IN YEAST
Occurs
during fermentation.
ANAEROBIC
RESPIRATION IN MUSCLES
Causes
muscle cramps during heavy exercise.
AEROBIC
RESPIRATION
Occurs in
mitochondria.
Aerobic
respiration releases much more energy.
ATP – ENERGY
CURRENCY
ATP stores
energy released during respiration.
Formation
ATP provides
energy for:
- Muscle
contraction
- Protein
synthesis
- Nerve
impulse conduction
RESPIRATION
IN PLANTS
Plants
exchange gases through:
Stomata
During Day
- Oxygen
released
- Carbon
dioxide used
During Night
- Carbon
dioxide released
RESPIRATION
IN FISHES
Fishes use:
Gills
to absorb
dissolved oxygen from water.
Since water
contains less oxygen:
- Fish
breathe faster than humans.
HUMAN
RESPIRATORY SYSTEM
Main organs:
- Nostrils
- Nasal
cavity
- Trachea
- Bronchi
- Lungs
- Alveoli
FUNCTIONS OF
NOSTRILS
- Filter
dust
- Warm
air
- Moisturise
air
TRACHEA
Contains
cartilage rings preventing collapse.
ALVEOLI
Tiny
balloon-like air sacs in lungs.
Functions
- Exchange
of gases
- Provide
large surface area
GAS EXCHANGE
IN ALVEOLI
|
Gas |
Direction |
|
Oxygen |
Alveoli →
Blood |
|
Carbon
dioxide |
Blood →
Alveoli |
HAEMOGLOBIN
Respiratory
pigment present in RBCs.
Function
Transports
oxygen.
EFFECTS OF
SMOKING
Smoking
damages cilia present in respiratory tract.
Results:
- Lung
infection
- Persistent
cough
- Lung
cancer
5.4
TRANSPORTATION
Transportation
is the movement of:
- Food
- Oxygen
- Hormones
- Waste
products
throughout
the body.
TRANSPORTATION
IN HUMAN BEINGS
Components:
- Heart
- Blood
- Blood
vessels
BLOOD
Blood
contains:
- Plasma
- RBCs
- WBCs
- Platelets
FUNCTIONS OF
BLOOD COMPONENTS
|
Component |
Function |
|
RBCs |
Carry
oxygen |
|
WBCs |
Fight
infection |
|
Platelets |
Blood
clotting |
|
Plasma |
Transport
substances |
HUMAN HEART
The heart is
a muscular pumping organ with four chambers:
- Right
atrium
- Right
ventricle
- Left
atrium
- Left
ventricle
DOUBLE
CIRCULATION
Blood passes
through heart twice in one complete cycle.
Advantages
- Efficient
oxygen supply
- No
mixing of blood
BLOOD
VESSELS
Arteries
- Carry
blood away from heart
- Thick
elastic walls
Veins
- Carry
blood toward heart
- Have
valves
Capillaries
- One-cell
thick walls
- Exchange
substances with tissues
BLOOD
PRESSURE
Normal blood
pressure:
120/80 mm Hg
High blood
pressure:
Hypertension
PLATELETS
Help in:
Blood
clotting
Prevent
excessive blood loss during injury.
LYMPH
Colourless
tissue fluid.
Functions
- Carries
absorbed fats
- Returns
excess fluid to blood
TRANSPORTATION
IN PLANTS
Plants use:
- Xylem
- Phloem
XYLEM
Transports:
- Water
- Minerals
from roots
to leaves.
TRANSPIRATION
Loss of
water vapour from leaves.
Functions
- Creates
transpiration pull
- Helps
upward movement of water
- Maintains
temperature
ACTIVITY 5.8
– TRANSPIRATION
Observation
Water
droplets appear inside plastic cover placed over plant.
Conclusion
Plants lose
water through transpiration.
PHLOEM
Transports
prepared food from leaves to other parts of plant.
Process
Translocation
Occurs using
ATP energy.
Food can
move:
- Upward
- Downward
5.5
EXCRETION
Excretion is
the removal of harmful metabolic wastes from the body.
EXCRETORY
SYSTEM IN HUMAN BEINGS
Consists of:
- Kidneys
- Ureters
- Urinary
bladder
- Urethra
FUNCTIONS OF
KIDNEYS
Remove:
- Urea
- Uric
acid
- Excess
water
- Excess
salts
from blood.
NEPHRON
Structural
and functional unit of kidney.
Parts:
- Bowman’s
capsule
- Glomerulus
- Tubule
- Collecting
duct
URINE
FORMATION
Steps:
- Filtration
- Reabsorption
- Secretion
HEMODIALYSIS
(ARTIFICIAL KIDNEY)
Used when
kidneys fail.
Principle
Blood is
purified artificially using dialysis machine.
EXCRETION IN
PLANTS
Plants
remove wastes by:
- Transpiration
- Storing
wastes in vacuoles
- Storing
gums and resins
- Shedding
leaves
- Releasing
wastes into soil
IMPORTANT
DIAGRAMS TO PRACTICE
- Human
digestive system
- Human
respiratory system
- Human
heart
- Nephron
- Nutrition
in Amoeba
- Stomata
- Alveoli
- Transportation
in plants
