The document discusses the principles and laws of thermodynamics, including the zeroth, first, second, and third laws, along with their applications in biological systems. It emphasizes that energy cannot be created or destroyed, only transformed, and outlines how these energy transformations affect living organisms and ecosystems. The third law indicates that as systems approach absolute zero, entropy becomes constant, highlighting the need for constant energy input in living systems to maintain order.

2. Introduction
Definations
Laws of thermodynamics
First law of thermodynamics
Second law of thermodynamics
Third law of thermodynamics
Applications
References

3. Thermodynamics is a Greek word which
means flow of heat energy in physical, chemical
and biological reactions.
• Thermodynamics is a branch of science
which deals with study of different
forms of energy and their interconversions
• It deals with energy changes in physical and chemical processes
INTRODUCTION

4. Sadi Carnot (1796–1832)
"FATHER OF THERMODYNAMICS”

5. Zeroth Law
First Law
Second Law
Third Law
LAWS OF THERMODYNAMICS

6. ZEROTH LAW OF THERMODYNAMICS
Thermal Equilibrium
“If two
thermodynamic
systems are each
in thermal
equilibrium with
a third, then they
are in thermal
equilibrium with
each other”.

7. When two bodies A and B are separately in thermal
equilibrium with a third body, they in turn are in
equilibrium with each other

8. We leave two cups of coffee (where one is observably hotter than
the other) on the kitchen table and we just leave them there.
After 30 minutes what will we notice about the two cups of coffee?
They will both cool down and will seemingly both have the
same temperature.

10. As the temperature is increased this mercury
expands since the area of the tube is constant.
Due to this expansion, the height is increased.
Now, the increase in the height of the mercury
label shows the changes in temperature and
basically helps us to measure it.
EXAMPLE
Lets consider a common example which we use in
our day-to-day life i.e; thermometer having mercury
in a tube

11. FIRST LAW OF THERMODYNAMICS
Law of Conservation of Energy

12. First law of thermodynamics is also
known as the law of conservation
of energy.
This states that “Energy can be neither
created nor destroyed. However, energy
can change forms, and energy can flow
from one place to another. The total energy
of an isolated system does not change”.

13. How does a hot cup of coffee get cold?
HOW ICE MELTS…?

14.  All biological organisms require energy to survive.
 Cells, for example, perform a number of important processes. These processes
require energy.
 In photosynthesis, the energy is supplied by the sun. Light energy is absorbed
by cells in plant leaves and converted to chemical energy.
 The chemical energy is stored in the form of glucose, which is used to form
complex carbohydrates necessary to build plant mass.
 The energy stored in glucose can also be released through cellular respiration.
 This process allows plant and animal organisms to access the energy stored in
carbohydrates, lipids, and other macromolecules through the production of
ATP.
 This energy is needed to perform cell functions such as DNA replication,
mitosis, meiosis, cell movement, endocytosis, exocytosis, and apoptosis.
First Law of Thermodynamics in Biological Systems

15. SECOND LAW OF THERMODYNAMICS
Law of Increased Energy

16. Out of these Clausius statement, Kelvin statement and Principle of
Carathéodory are the three most prominent classical statements.
Clausius statement:
”Heat cannot transfer from a low-temperature body to the high-
temperature body until unless there is an external force on the system”.
Kelvin-Plank’s Statement:
”It is impossible to build a device to operate on a cycle to receives heat
from a single reservoir and produce a net amount of work”.
Carathéodory’s Statement:
This is also known as the Principle of Carathéodory.
This law is completely on the mathematical axiomatic foundation.
In every neighbourhood of any state entropy(S) of an adiabatically enclosed
system, there are states inaccessible from entropy(S).

18.  As with other biological processes, the transfer of energy is not 100 percent efficient.
 In photosynthesis, for example, not all of the light energy is absorbed by the plant.
Some energy is reflected and some is lost as heat. The loss of energy to the
surrounding environment results in an increase of disorder or entropy.
 Unlike plants and other photosynthetic organisms, animals cannot generate energy
directly from the sunlight. They must consume plants or other animal organisms for
energy.
 The higher up an organism is on the food chain, the less available energy it receives
from its food sources.
 Much of this energy is lost during metabolic processes performed by the producers
and primary consumers that are eaten.
 Therefore, much less energy is available for organisms at higher trophic levels.
(Trophic levels are groups that help ecologists understand the specific role of all
living things in the ecosystem).
 The lower the available energy, the less number of organisms can be supported.
Second Law of Thermodynamics in Biological Systems

19. THIRD LAW OF THERMODYNAMICS
ABSOLUTE ZERO

20. “The temperature of a system approaches absolute zero, its
entropy becomes constant, or the change in entropy is zero”.
The third law of thermodynamics predicts the properties of a system and
the behavior of entropy in a unique environment known as absolute
temperature.
The entropy of a bounded or isolated system becomes constant as its
temperature approaches absolute temperature (absolute zero).

21. Living systems require constant energy input to maintain their highly
ordered state. Cells, for example, are highly ordered and have low
entropy.
In the process of maintaining this order, some energy is lost to the
surroundings or transformed. So while cells are ordered, the
processes performed to maintain that order result in an increase in
entropy in the cell's/organism's surroundings.
The transfer of energy causes entropy in the universe to increase
THIRD LAW OF THERMODYNAMICS IN BIOLOGICAL SYSTEMS

22. The study of internal biochemical dynamics as:
ATP hydrolysis, protein stability, DNA binding,
membrane diffusion, enzyme kinetics, and
other such essential energy controlled
pathways.
BIOLOGICAL THERMODYNAMICS

23.  “Engineering Thermodynamics” by M Achuthan
 “Fundamentals of Thermodynamics” by R E Sonntag and C
Borgnakke and G J Van Wylen
 “Fundamentals of Thermodynamics and Applications” by Muller
 Bioenergetics and Thermodynamics | Plants
 Laws of Thermodynamics in Bioenergetics (With Diagram)
REFERENCES