It is a biologically known fact that, right since the first living organism
breathed for the first time billions of years ago, it needed food to survive and grow.
Food is something without which growth, development, and evolution would have
been impossible. Every living thing on the face of the earth, irrespective of whether it
belongs to the plant or animal kingdom, needs nutrition to survive, grow, and
reproduce. All the living organisms on earth are therefore, dependent on each other
for survival in some way or the other and that is what we call the ecosystem.
The food chain in nature includes both plants and animals who are a part of it and
even the tiniest ecosystem has a food chain for itself.
As mentioned above, without food, there is no survival. Therefore, the answer
for why is food important is that, when you consume some mode of food and
nutrition, the body functions in a particular manner. Without a catalyst, there is no
product that is formed and for all living things like plants, animals, and humans,
certainly food is the catalyst. Hence, when you consume food, nutrition is provided to
the body for the production of energy and in turn, the body is functional. The food
pyramid gives us an idea about its value in our lives and how, in a very pictorial and
clear manner. This is a very biological and medical purpose of food as you need it for
the cycle of life. Charles Darwin also supported the importance of food through the
theory of "survival of the fittest".
Transport in living organisms
However, the evolution of more and more complex body structures
necessitated the development of proper transport system, and more complex the
organisms are the more elaborate transport system they have. The complexity of
transport system is related to the size and the metabolic rate of the living organism.
The materials to be transported are taken close to tissues be the transport
system so that diffusion can occur efficiently into the cells. The primary function of
the transport system is to maintain a link between all cells of the body and the
external environment. It transports the nutrients to the points where they are to be
used facilitates the elimination of metabolic wastes of each cell and transports surplus
substances to the specialized storage tissues or to outside their bodies.
The way in which organisms obtain energy to power their life processes is
called respiration, and this takes place in their cells.
Respiration takes the energy stored in foods (such as glucose) and changes it
into a form that can be used by the cell.
Mitochondria are the powerhouses of the cell
- they release all the energy it needs. Glucose enters the mitochondria and
combines with oxygen. This process gives off energy in the form of a chemical called
ATP. Carbon dioxide and water are the waste products. The term «respiration» means
the exchange of gases (oxygen and carbon dioxide) which takes place between the
living organism and the environment. One must consider that in higher organisms this
exchange takes place at several different levels. An initial exchange must occur
between the air in the lungs, from which the oxygen is being continually taken up and
into which carbon dioxide is being continually poured, and the external air. This is
the process of external respiration.
The composition of the air inside the lungs is different from that of the air
which we inhale. The content of alveolar air is very constant, especially the one of
carbon dioxide, the partial pressure of which is normally 40 mm of mercury. This
constancy is the result of a self-regulating mechanism by which the respiratory
activity is governed by the amount of carbon dioxide which has been eliminated from
The exchange of gases varies according to the size and activity of the
organism. In man at rest the absorption of oxygen reaches about 0.25 liter a minute
and the elimination of carbon dioxide 0.2 liter. At a time of maximum muscular
activity, the consumption of oxygen and the production of carbon dioxide may both
exceed 4 liters a minute.In physiology, respiration is defined as the movement of
oxygen from the outside air to the cells within tissues, and the transport of carbon
dioxide in the opposite direction.
The physiological definition of respiration should not be confused with the
biochemical definition of respiration, which refers to cellular respiration: the
metabolic process by which an organism obtains energy by reacting oxygen with
glucose to give water, carbon dioxide and 38ATP (energy). Although physiologic
respiration is necessary to sustain cellular respiration and thus life in animals, the
processes are distinct: cellular respiration takes place in individual cells of the
organism, while physiologic respiration concerns the bulk flow and transport of
metabolites between the organism and the external environment.
In microbiology, the term isolation refers to the separation of a strain from a
natural, mixed population of living microbes, as present in the environment, for
example in water or soil flora, or from living beings with skin flora, oral flora or gut
flora, in order to identify the microbe(s) of interest. Historically, the laboratory
techniques of isolation first developed in the field of bacteriology and parasitology
(during the 19th century), before those in virology during the 20th century. Methods
of microbial isolation have drastically changed over the past 50 years, from a labor
perspective with increasing mechanization, and in regard to the technology involved,
and hence speed and accuracy.
The laboratory techniques of isolating microbes first developed during the 19th
century in the field of bacteriology and parasitology using light microscopy. Proper
isolation techniques of virology did not exist prior to the 20th century. The methods
of microbial isolation have drastically changed over the past 50 years, from a labor
perspective with increasing mechanization, and in regard to the technologies
involved, and with it speed and accuracy.
In order to isolate a microbe from a natural, mixed population of living
microbes, as present in the environment, for example in water or soil flora, or from
living beings with skin flora, oral flora or gut flora, one has to separate it from the
mix. This can be achieved in two ways;
Traditionally microbes have been cultured in order to identify the microbe(s) of
interest based on its growth characteristics. Depending on the expected density and
viability of microbes present in a liquid sample, physical methods to increase the
gradient as for example serial dilution or centrifugation may be chosen. In order to
isolate organisms in materials with high microbial content, such as sewage, soil or
stool, serial dilutions will increase the chance of separating a mixture.
In a liquid medium with few or no expected organisms, from an area that is
normally sterile (such as CSF, blood inside the circulatory system) centrifugation,
decanting the supernatant and using only the sediment will increase the chance to
grow and isolate bacteria or the usually cell-associated viruses.
If one expects or looks for a particularly fastidious organism, the
microbiological culture and isolation techniques will have to be geared towards that
microbe. For example, a bacterium that dies when exposed to air, can only be isolated
if the sample is carried and processed under airless or anaerobic conditions. A
bacterium that dies when exposed to room temperature (thermophilic) requires a pre-
warmed transport container, and a microbe that dries and dies when carried on a
cotton swab will need a viral transport medium before it can be cultured successfully.
More recently, microbes have been isolated without culturing them. Samples
are inoculated into microtiter plates or cartridges extracting their particular genetic
material (DNA or RNA) which can be used to identifying them.
In all living organisms’ plants and animals, physiological processes are
continually taking place in their bodies. In order to sustain life, these processes must
be kept going on for which the materials required, must be constantly transported to
and from all parts of the body right down to the individual cells. Materials are also to
be transported between the cell organism and external environment. In unicellular
and simple multicultural organisms, the distribution of materials can be adequately
brought about by diffusion and streaming movements of the cytoplasm.
All living things have the ability to move without outside help. This makes
them different from non-living things that only move if they are pushed or pulled by
something else e.g. a stone that is thrown, a stream that flows, paper blowing about.
No outside force has to ‘push-start’ growth of a green shoot towards sunlight or a dog
to scratch, or YOU to move…. as you are doing right now! All these things are
living, so they move by themselves!
You should be able to: state the difference between movement and locomotion.
explain the importance of movement to plants describe the different types of
movements in plants distinguish between growth movements in plants and
movements in animals.
Movement is rhythmical progression, resulting in a change of pace, posture,
position or place. All living organisms show movement of one kind or another. They
have the innate ability to move substances from one part of their body to another -
called internal movement. Many living organisms also show external movement as
well -- they can move various body parts, or move their entire body from place to
place, i.e. locomotion.
Find water/soil nutrients, and hold leaves to get maximum sunlight Seek and
capture food Obtain support
Protect themselves from damage from: touch/pressure, or sudden temperature
change Disperse seeds
Unlike many animals, plant movement is non- locomotor. Movement is
confined to specific plant parts (e.g. Stems/roots) and is not always obvious because
it is very slow. Plant movements are often related to growth. Tropisms are directional
growth responses to an external, unilateral stimulus. Tropic growth movements
cannot be reversed! Tropic growth movements are caused by chemicals called auxins
that are produced in stem and root tips and cause selective cell growth and elongation
which will result in either overall growth or growth curvatures of plant parts affected
by the auxins.
Plant movement can also be a non-directional response to a stimulus, called a
nastic movement. Plant parts (e.g. leaves and leaf structures, flowers, fruits) respond
to touch, light, temperature changes and humidity e.g. by opening/closing/folding or
bursting to disperse seeds etc.
Like plants, invertebrate animals such as sea anemones, adult sponges and
corals, move body parts only and are non- locomotor. These movements are
somewhat like nastic movements in plants since they are temporary and reversible.
For example, below left -sea anemones can open/close tentacles. Like plants, many
invertebrates move in response to light, moisture, chemicals, temperature changes
and, additionally, to magnetic and electrical fields. Their movement differs from that
of plants, because the animal’s entire body moves about from place to place =
locomotion. Such animals move about with the aid of cilia, flagella, false ‘legs/feet’,
hydrostatic pressure against their body wall, or they may have an exoskeleton that
enables muscle attachment for locomotion.
If we want to now if an organism is a living animal, we usually observe it or
prod it to see if it moves. This is because, in response to stimuli, all animals move
various body parts and many can also carry on locomotion. In animals, movement
and locomotion usually involves the action of muscles (contractile tissue).
You should be able to: discuss the importance of locomotion in animals.
Describe movement in animals. differentiate between growth movements in plants
and locomotion in animals.
Locomotion is a common response to all kinds of stimuli. Animals to: move
about Escape danger Protect themselves from damage from pressure, pain, or sudden
temperature changes Find a mate and to reproduce
Why else would the ability to move about be important to animals? Seek and
capture food CHECK •To seek shelter, a suitable habitat/climate; •To avoid
competition for food/water, living space etc. Muscles help animals such as dogs,
whales, spiders, snakes, worms, flies and humans to move from place to place.
Muscles also move body parts and things inside the animal’s body. In fact, no animal
could move anything inside or outside of its body if there were no muscles. Without
muscles, you wouldn't be alive for very long!
1. The Coordination System Coordination systems work together to process
information received from stimuli and to produce appropriate responses. Animals
have two coordination systems:• the nervous system and• the endocrine system.
2. The Nervous System• The nervous system regulates the body’s activities and
responses. It works by means of specialized cells called neurons which transmit
information in the form of nerve impulses.
3. Nervous System Responses
4. The Endocrine System• The endocrine system regulates and coordinates the
body functions by means of chemical substances called hormones. The endocrine
system regulates functions which require maintained responses. These include
changes during the metamorphosis of some animals, growth, and the production of
milk in mammals.
5. Endocrine System Responses
6. Summary• The coordination system tells the body how to respond to a
stimulus. The body can coordinate a response quickly with a nerve impulse or over
time as chemicals build up and break down in the blood stream.
Timing and coordination of specific events are necessary for the normal
development of an organism, and these events are regulated by a variety of
Transcription factors are molecules that control gene expression. They are
considered "trans" (as opposed to "cis") because they are not part of the DNA
sequence directly adjacent to the gene itself. Generally proteins, they can either
decrease or increase expression depending on how they interact with the locus.
Homeotic genes are genes which regulate the development of anatomical
structures in various organisms such as insects, mammals, and plants.
Determine the direction of developmental fates of groups of cells in a segment
of the embryo.
Include a DNA sequence called the home box that is similar in all homeotic
Programmed cell death is part of a normal process in development,
metamorphosis and homeostasis. It is responsible for sculpting away cells that are no
longer required in the developmental process or have become ‘life-expired’ and need
to be replaced. Examples of this include the removal of tail cells during tadpole/frog
metamorphosis; the removal of ‘webbing’ that occurs between digits in human
embryo development, and the removal of brain cells that have not ‘linked up’ during
development – about half the original number. Many chemotherapy treatments for
cancer work by inducing cancer cells to undergo apoptosis.
new individual organisms – "offspring" – are produced from their "parents".
Reproduction is a fundamental feature of all known life; each individual organism
exists as the result of reproduction. There are two forms of reproduction: asexual and
In asexual reproduction, an organism can reproduce without the involvement of
another organism. Asexual reproduction is not limited to single-celled organisms.
The cloning of an organism is a form of asexual reproduction. By asexual
reproduction, an organism creates a genetically similar or identical copy of itself. The
evolution of sexual reproduction is a major puzzle for biologists. The two-fold cost of
sex is that only 50% of organisms reproduce and organisms only pass on 50% of their
organisms, called gametes, which contain half the number of chromosomes of normal
cells and are created by meiosis, with typically a male fertilizing a female of the same
species to create a fertilized zygote. This produces offspring organisms whose genetic
characteristics are derived from those of the two parental organisms.
The process by which cells and organisms produce other cells and organisms of
the same kind. Cell reproductionusually involves division of a cell into two identical
parts by means of mitosis or into four different parts by meiosis. The reproduction of
organisms by the union of male and female reproductive cells (gametes) is
called sexualreproduction. Most multicellular animals reproduce sexually.
Reproduction in which offspring are produced by asingle parent, without the
union of reproductive cells, is called asexual reproduction. The fission (splitting)
ofbacterial cells is a form of asexual reproduction. Many plants and fungi are
capable of reproducing both sexually andasexually, as are some animals, such
Have you ever watched a caterpillar turn into a butterfly? If so, you’re probably
familiar with the idea of a life cycle. Butterflies go through some fairly spectacular
life cycle transitions—turning from something that looks like a lowly worm into a
glorious creature that floats on the breeze. Other organisms, from humans to plants to
bacteria, also have a life cycle: a series of developmental steps that an individual goes
through from the time it is born until the time it reproduces.
The cell cycle can be thought of as the life cycle of a cell. In other words, it is
the series of growth and development steps a cell undergoes between its “birth”—
formation by the division of a mother cell—and reproduction—division to make two
new daughter cells.
Stages of the cell cycle
To divide, a cell must complete several important tasks: it must grow, copy its
genetic material (DNA), and physically split into two daughter cells. Cells perform
these tasks in an organized, predictable series of steps that make up the cell cycle.
The cell cycle is a cycle, rather than a linear pathway, because at the end of each go-
round, the two daughter cells can start the exact same process over again from the
In eukaryotic cells, or cells with a nucleus, the stages of the cell cycle are
divided into two major phases: interphase and the mitotic (M) phase.
- During interphase, the cell grows and makes a copy of its DNA.
- During the mitotic (M) phase, the cell separates its DNA into two sets and
divides its cytoplasm, forming two new cells.
Image of the cell cycle. Interphase is composed of G1 phase (cell growth),
end of interphase comes the mitotic phase, which is made up of mitosis and
cytokinesis and leads to the formation of two daughter cells. Mitosis precedes
cytokinesis, though the two processes typically overlap somewhat.
The spatial and temporal regulation of interactions between molecules is
fundamental to life. Growth & Development is dedicated to understanding how these
coordinated interactions lead to cell growth, cell division and the development of
Life is more complicated than a binary interaction of two factors and its
regulation; various processes need to occur in parallel for a cell to function normally.
For this reason, this research area covers a broad range of aspects from signal
transduction, gene regulatory networks, cell division and cell cycle control to
membrane transport, protein and mRNA transport, in a variety of experimental
organisms such as bacteria, yeasts, worms, flies, fish and mammals.