Abiotic Factors. (2).pdf

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Classes Notes
Organisms and Populations
Abiotic factors, Thermoregulation, Osmoregulation

1
Key Takeaways
2 Regulators
Thermoregulation
Abiotic factors of
ecosystem
Light
Soil
Summary
Osmoregulation

Abiotic Factors
Abiotic factors
Temperature
Water
Light
Soil
❖ Abiotic factors include temperature, water, light and soil that
surround the organism.

Abiotic Factors
Photosynthesis
Flowering
❖ Plants produce food through
photosynthesis, where sunlight is the
source of energy.
❖ Hence, light is another important
abiotic factor
❖ The availability of light on land is
closely linked with that of temperature
since the sun is the source for both.
❖ Plants depend on light not only for
photosynthesis, but also for ﬂowering.
Light

Abiotic Factors
❖ Not all plants receive same amounts of sunlight
❖ Many species of small plants (herbs and shrubs) growing in forests are adapted
to photosynthesise under very low light conditions because they are constantly
overshadowed by tall, canopied trees.
❖ In order to cope with low light, these plants have adapted to have large leaves
to capture as much sunlight is available.
Light
❖ Small plants on the forest ﬂoor
receive low amounts of light
❖ Have large leaves to capture
sunlight

Abiotic Factors
Animals indirectly depend
on sunlight for energy
❖ For many animals too, light is an
important factor.
❖ Animals also indirectly depend on
sunlight for energy.
❖ Plants photosynthesise and produce
food.
❖ Animals eat them to get energy.
Light

❖ Plants also use the night-day and seasonal variations in light
intensity and duration (photoperiod) as cues for timing their
ﬂowering.
Light
Abiotic Factors
Abiotic Factors

Abiotic Factors
Foraging
Searching for food resources
Reproduction
Giving birth to young ones
Migration
Movement of animals or
birds on seasonal basis
Light

Recall! Chemoautotrophs
Chemoautotrophs:
Organisms that obtain their energy from the oxidation of inorganic
compounds like ammonia
❖ The organisms that live deep down on ocean
ﬂoor have ability to feed on dead organic matter
raining down from above zones.
❖ Some organisms rely on chemicals coming out
of hydrothermal vents as energy source. They
are chemoautotrophs.

Abiotic Factors
Blue light reaches deep ocean
Red algae is found in deep oceans
❖ The spectral quality of solar radiation is also important for life.
❖ Not all the colour components of the visible spectrum are available for
marine plants living at diﬀerent depths of the ocean.
❖ Blue light reaches the deep ocean. Since red algae absorb blue light, they
are found in deep oceans.
Light

Abiotic Factors
Soil
❖ The rocks in the mountain break due to impact of factors like
sunlight, rain, heavy winds, gradually resulting in soil formation.

1
Climate
2
Weathering
3
Soil
development
process
Causes
Abiotic Factors
Soil
Nature and properties of soil vary in diﬀerent places

Abiotic Factors
1
2
Composition
3
Aggregation
Grain size
Characteristics
of soil
Soil

Did You Know ?
The water moves diﬀerently in diﬀerent soils.
Soil type 1 Soil type 2 Soil type 3 Soil type 4
Movement of water through soil is called percolation

Recall! Minerals
Small amounts
Copper
Manganese
Sulphur
Iron
Carbon
Oxygen
Nitrogen
Phosphorous
Large amounts
Hydrogen
Potassium

Abiotic Factors
❖ Extent of vegetation in any
area depend on these factors
Topography
Minerals Percolation
pH
0 pH
10 pH
Soil

Crabs
Clams
❖ Similarly, in the aquatic
environment, the
sediment-characteristics
of soil often determine
the type of animals that
can thrive in this habitat.
❖ Benthic animals like
crabs and clams are
found in the areas which
are near to sea.
Abiotic Factors

Recall! Enzyme Activity
❖ Enzyme activity is maximum at optimum temperature and pH.
❖ Optimum means to be the most conducive to a favourable
outcome.
Rate
of
enzyme
activity
Temperature (⁰C)
Maximum enzyme activity
0 10 20 30 37 40 50
Optimum
temperature and pH
pH
1 2 3 4 5 6 7 8 9 10

Recall! Metabolism
❖ The enzymes required for cellular
respiration are crucial for our
metabolic pathways to work
properly.
❖ Any reduction in enzyme activity
slows down cellular respiration
(ATP production) and hence
makes a person feel tired and
weak.
Metabolic pathways

Regulators
● Regulators are organism that use energy to maintain internal
environment at a steady state regardless of the external environment.
● This property is called homeostasis.
External environment
Internal environment

Homeostasis
Homeostasis refers to the capacity of the body to maintain the
stability of internal variables, such as temperature, acidity
and water level against constant environmental disturbance.
370
C Body temperature
72 beats/minute heart rate
Blood sugar level
Stable internal variables

Recall! Evolutionary Fitness
Evolutionary ﬁtness is a measure of how well a species can survive and
reproduce in its environment.
Children
Grand-
children
Parent
Evolution of homeostasis increased ﬁtness

Regulators
Temperature Osmolarity
370
C
270
C
250
C
450
C
400
C
100
C
Cl-
Mg
Ca
Glucose
K
Na
The two most aﬀected internal balances that require regulation are:

Thermoregulation
❖ Organism’s ability to maintain body temperature within a narrow
range.
❖ Thermoregulation, also called heat regulation, is the maintenance
of an optimum temperature range by an organism.
Normal body
temperature
370
C

Thermoregulation
Normal body
temperature
Sweating and evaporation
Cooling
Temperature
rises
Heat radiates
Capillaries dilate
Skin
❖ In summer or desert environment, where temperature is higher than 37o
C, the body
temperature also rises.
❖ This is sensed by the nervous system (hypothalamus), and it signals following changes.
➢ Dilation of capillaries near skin – this allows heat to radiate from the body
➢ Sweating and evaporation – helps in evaporative cooling of the body.
❖ Thus, normal body temperature is maintained irrespective of the conditions outside.

Thermoregulation
Capillaries constrict
Heat retained
Shivering Warming
Normal body
temperature
Temperature
falls
Skin
● In cold and icy environment, where the temperatures are below 370
C, the body
temperature drops a little.
● This is sensed by our nervous system (hypothalamus), and it signals following changes:
○ Constriction of capillaries near skin – this prevents body heat from escaping
○ Shivering – cold induces involuntary contraction of skeletal muscles which
generates a lot of heat
● Thus, normal body temperature is maintained irrespective of the condition outside.

Regulators
Endotherms
Birds
Mammals Lower vertebrates
e.g-Tuna, great white shark
Invertebrates
e.g- Winged insects
● Animals that use metabolism to generate heat and maintain
their body temperature and osmolarity are called regulators.

Regulators
● Not all regulators can regulate both
temperature and osmolarity.
Cannot regulate
body temperature
Can regulate body
ﬂuid osmolarity
● Plants cannot thermoregulate.

Osmoregulation
● Active regulation of body fluid
osmolarity is called osmoregulation.
● It is different for freshwater fishes and
marine fishes.

Recall! Osmosis
Solute
molecule
Water
Semi-permeable membrane
A B
A → B
Osmosis is diﬀusion of water from its higher concentration to its lower concentration
across a semipermeable membrane till equilibrium is reached.

Osmoregulation in Freshwater Fish
Hypertonic
Freshwater
Solute molecule
● Fish is hypertonic (solution having
more concentration of solute).
● The osmolarity of surrounding water
is less than osmolarity of its body.
Gills actively absorb salts
salts
● This is because the gills actively
absorb ions required to maintain its
body function. (Freshwater ﬁshes do
not drink water)

Osmoregulation in Freshwater Fish
Endosmosis through skin
and gills
Dilute urine excreted
H2
O H2
O
NH3
+ H2
O
H2
O
● This makes the fish hypertonic compared to
the surrounding water - this difference leads
to endosmosis (water moves from
surrounding into fish) through gills and skin.
● To tackle the problem of excess incoming
water, the fish excretes dilute urine.
● Freshwater fishes are ammonotelic.
● Ammonotelic- Nitrogenous waste is excreted
in the form of ammonia.

Osmoregulation in Marine Fish
Hypotonic
Sea water
Solute molecule
● Marine fish is hypotonic, the osmolarity of
surrounding water is more than the
osmolarity of its body.
Seawater
Intake of salts with water
H2
O
● Hypotonic nature of fish’s body fluid leads
to exosmosis (water moves from fish to
surrounding). To balance out this loss of
water, marine fishes drink seawater.

Osmoregulation in Marine Fish
Salt
Actively pumps out salt
Salt
Concentrated urine excreted
● The salts ingested along with water
are actively pumped out through gills.
● To tackle the problem of excess water
loss and surplus salts, the ﬁsh excretes
concentrated urine.
● Marine ﬁshes are ureotelic.
● Ureotelic- Nitrogenous waste is excreted
in the form of urea.

Ecosystem
Any
living organisms
Biotic
Physical
environment of a
living organism
Abiotic
Summary
Temperature
Water
Light
Soil

Summary
Response to abiotic factors
Response to
abiotic factors
Regulate
Conform
Some animals can regulate their body function
irrespective of external environment.
Some conform to match the external
environment and reduce energy use.

Summary
● Regulators are organism that use energy to maintain internal
environment at a steady state regardless of the external environment.
● Homeostasis refers to the capacity of the body to maintain the stability of
internal variables, such as temperature, acidity and water level against
constant environmental disturbance.
● Thermoregulation refers to organism’s ability to maintain body
temperature within a narrow range.
● Osmoregulation refers to active regulation of body ﬂuid osmolarity is
called osmoregulation.

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