Biophysicists study life at every level, from atoms and molecules to cells, organisms, and environments. As innovations come out of physics and biology labs, biophysicists find new areas to explore where they can apply their expertise, create new tools, and learn new things. The work always aims to find out how biological systems work. Biophysicists ask questions, such as:
How do protein machines work? Even though they are millions of times smaller than everyday machines, molecular machines work on the same principles. They use energy to do work. The kinesin machine shown here is carrying a load as it walks along a track. Biophysics reveals how each step is powered forward.
Diversity, structure and function of living organisms. Diversity in living organisms In biology, an organism is any contiguous living system, such as an animal, plant, fungus, archaeon, or bacterium. All known types of organisms are capable of some degree of response to stimuli, reproduction, growth and development and homeostasis. An organism consists of one or more cells; when it has one cell it is known as a unicellular organism; and when it has more than one it is known as amulticellular organism. Most unicellular organisms are of microscopic size and are thus classified as microorganisms. Humans are multicellular organisms composed of many trillions of cells grouped into specialized tissues and organs.
An organism may be either a prokaryote or a eukaryote. Prokaryotes are represented by two separate domains, the Bacteria andArchaea. Eukaryotic organisms are characterized by the presence of a membrane-bound cell nucleus and contain additional membrane-bound compartments called organelles (such as mitochondria in animals and plants and plastids in plants and algae, all generally considered to be derived from endosymbiotic bacteria). Fungi, animals and plants are examples of kingdoms of organisms within the eukaryotes.
Estimates on the number of Earth’s current species range from 10 million to 14 million, of which only about 1.2 million have been documented. More than 99% of all species, amounting to over five billion species, that ever lived on Earth are estimated to beextinct. In July 2016, scientists reported identifying a set of 355 genes from the Last Universal Common Ancestor (LUCA) of all organisms living on Earth.
1) Every living organism is unique and this uniqueness is the basis of the vast diversity displayed by the organisms in our world.
2) This huge diversity is the result of evolution, which has occurred over millions of years.
3) The massive biological diversity can only be studied by classification i.e. arranging organisms into groups based on their similarities and differences.
4) Different characteristics are used to determine thehierarchy of classification.
5) The primary characteristics that determine the broadest divisions in classification are independent of any other characteristics. The secondary characteristics depend on the primary ones.
6) Prokaryotic or eukaryotic cell organization is the primary characteristic of classification, since this feature influences every detail of cell design and capacity to undertake specialized functions.
7) Being a unicellular or multicellular organism formsthe next basic feature of classification and causes huge differences in the body design of organisms.
8) The next level of classification depends on whether the organism is autotrophic or heterotrophic. Further classification depends on the various levels of organization of the bodies of these organisms.
9) The evolution of organisms greatly determines theirclassification.
10) The organisms who evolved much earlier have simple and ancient body designs whereas the recently evolved younger organisms have complexbody designs.
11) Older organisms are also referred to as primitive or lower organisms whereas the younger organisms are also referred to as advanced or higher organisms.
12) The diversity of life forms found in a region is biodiversity.
13) The region of mega-diversity is found in the warm and humid tropical regions of the Earth.
14) Aristotle classified organisms depending on their habitat.
15) Robert Whittaker proposed the five-kingdom scheme of classification, based on the cell structure, nutrition and body organization of the organisms.
16) The main characteristics considered in the five-kingdom scheme of classification are:
i) Presence of prokaryotic or eukaryotic cells.
ii) If eukaryote, whether the organism is unicellular or multicellular.
“Monophyletic tree of organisms”. Ernst Haeckel: Generelle Morphologie der Organismen, etc. Berlin, 1866. (Photo credit: Wikipedia)
The Food And Food Chain Of Living Organisms Where do you get the energy to ride your bike or walk up the stairs? Where does a cheetah get the energy to run after a hare? How does a tomato plant get the energy to make a tomato? All living things need a source of energy to live. They get this energy from food. However, different living things get their food in different ways. Some living things are able to make their own food. They are called producers. Plants are living things that are producers. Plants use sunlight, water, and air to make food. They use the energy in this food to live and grow. Other living things must find their own food because they cannot make it. They are called consumers. Consumers get energy by eating other living things. Some consumers, such as rabbits and cows, eat only plants. Other consumers, such as lions and snakes, eat only animals. Still other consumers, such as bears and raccoons, eat both plants and animals. How Living Things Get Food A tomato plant uses sunlight, water, and air to make food. A hare eats plants. A cheetah eats other animals. A bear eats both plants and animals.
The food chain of living things
Animals get their energy from food. Herbivores, like deer and hare, feed on plants. Carnivores, like lions and wolves, eat meat. Omnivores, which include pigs, bears, and humans, eat both plants and animals. In an ecosystem, all the organisms that depend on one another in order to eat form a food chain. Plants are at the bottom of this chain. They get their energy from the sun, which allows them to manufacture the substances they need for their development. Most animals depend directly or indirectly on plants. In this way, even carnivores that feed on herbivores depend on the plants that feed their prey.
A superpredator is a carnivorous animal that is not the prey of any other species. It is at the top of the food chain. Raptors, tigers and wolves are examples of superpredators.
The flesh of other animals is the principal food of carnivores. For example, snakes eat small rodents.
Herbivores are animals that eat plants. Giraffes, which eat the leaves of acacia trees, are herbivores, as are certain rodents that eat seeds.
Plants use the energy of the sun to manufacture the nutrients they need from the water, the carbon dioxide present in the air and the mineral elements in the soil. Trees, flowers, cereal grains, mosses and seaweeds are examples of plants.
Decomposers feed on carcasses, excrement and plant remains. Bacteria, microscopic fungi and certain small animals, such as earthworms, are decomposers. In decomposing organic matter, they release mineral elements that are then used by plants to help them develop.
Special relationships, for better or worse
Some organisms benefit from other species, without necessarily eating them. These special relationships have different names, depending on the type of association. Symbiosis is the association of two organisms of different species that mutually benefit from living together and cannot survive without each other. For example, coral is associated with algae, called zooxanthellae. It is a relationship that is vital to both.Mutualism is a relationship of mutual aid between two organisms of different species. In this way, the sea anemone and the clownfish protect each other, but their association is not vital. Commensalism is an association where one species benefits from another, without harming it or being beneficial to it. For example, the remora is a fish that attaches itself to another organism, such as a shark, and travels with it without disturbing it. Finally, parasitism is a harmful association, where one species lives off another, using that species’ resources for its own benefit. Certain flatworms, called tapeworms, parasitize the intestine of mammals.
Examples of algae
Formed from the association of an alga and a fungus, lichens live in symbiosis. The alga manufactures the organic matter needed by both partners, while the fungus supplies them with water and mineral elements.
Examples of lichens
The dodder, a parasitic plant, has no leaves and is incapable of photosynthesis. Unlike other plants, it cannot use the sun’s energy in order to develop. It must live wound around the stalk of another plant, out of which it pumps organic matter using its suckers.
The remora, a fish of the tropical seas, attaches itself to the belly of a shark with an organ that acts like a suction cup. In this way, it travels long distances, benefiting from the protection of the shark and collecting its food scraps without harming it. This is called commensalism.
Transport in living things.(transport system in human) In this chapter you will learn:
1. Importance of water to life
2. Processes involved in transport of material across the cell, diffusion, active transport and osmosis.
3. Turgor and its importance in plants.
4. Transport of water and salts in plants.
5. Transpiration and factors affecting it.
6. Path of organic material in plants.
7. Open and closed circulatory system of animals and circulatory system of man.
The movement of substances from one part to another part within the body of an organism is called transport
Transport in unicellular organisms:
In simple and unicellular living organisms there is no need of any special transport system.The oxygen and dissolved substances from the outside enviroment can diffuse into the protoplasm directly.
living organisms Blood groups and Blood diseases.
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 (fig. 12.1).
Fig. 12.1 Streaming movement of cytoplasm (in Amoeba)
However, the evolution of more and more complex body structures recessitated 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 out side their bodies.
Respiration In Living Organism Respiration is the process in which food is broken down into smaller particles along with the liberation of energy. The energy released is utilized for various metabolic activities. In this process oxygen is inhaled inside by a living organism when they breathe in and carbon dioxide is exhaled out.
Respiration process in humans:
In human beings, oxygen is inhaled inside the human body through nose or mouth. Oxygen is transferred to the entire body and enters the cell. Inside the cell food particles are broken down into smaller pieces in the presence of oxygen. During the breakdown of food particles, energy is released in the form of ATP. This energy released is utilized in certain metabolic activities.
C6H12O6 + 6O2 –> 6CO2 + 6H2O + ATP
Respiration process can be of two types:
Breathing is a process in which air moves inside the body and outside the body. It consists of two phase:
Inhalation: Air enters the body of a living organism in this process.
Exhalation: In this process, air is released outside the body of a living organism.
Breathing rate: It can be defined as the number of times a person can breathe in a minute. With the increase in physical activity the breathing rate increases.
The above figure shows the respiration process. In this process, oxygen-rich air enters the body through the nose. From nose, it is transferred to trachea through pharynx and larynx where primary filtration of air takes place. From trachea, air is transferred to the bronchioles in the lungs. Bronchioles are the passageways to the alveoli.
Respiration in animals:
In this article we studied the respiration process and how the flow of air takes place in a living organism. We also got to know about the respiratory organs of different living organisms.
Isolation Of Living Organisms Objective:
To identify the bacterial unknowns in a mixed culture by morphological and biochemical methods.
The identification of bacteria is a careful and systematic process that uses many different techniques to narrow down the types of bacteria that are present in an unknown bacterial culture. It produces benefits for many aspects of the research of microorganisms and helps physicians correctly treat patients. Multiple tests were performed to provide the fermentation abilities, presence of certain enzymes, and certain biochemical reactions. Qualitative observations were made on the tests, which were compared to unknown bacteria identification key to aid with the identification process.
Various steps involved in the identification of unknown bacteria are:
Isolation: The importance of this step is to isolate pure colonies of bacteria. The streak plate is a qualitative isolation method; quadrant streaking is mostly done to obtain pure colonies. The inoculation of the culture is made on the agar surface by back and forth streaking with the inoculation loop over the solid agar surface. This will make a dilution gradient across the agar plate. Upon incubation, individual colonies will arise from the biomass.
The characteristics features of the colonies on solid agar media are then noted. This include
Surface: Smooth, wavy, rough, granular, papillate or glistening.
Edges: entire, undulate, crenated, fimbriate or curled.
Colour: Yelow, green etc.( Note the colour of the colony).
Structure: opaque, translucent or transparent.
Degree of growth : scanty, moderate or profuse.
Nature: discrete or confluent, filiform, spreading or rhizoid.
In order to obtain the pure culture of organism, the isolated colonies are aseptically transferred on to different nutrient agar slant tubes and incubated overnight at 37 degree Celsius. It is then stored for future purpose.
Staining is a simple basic technique that is used to identify microorganisms. Simple staining is used to study the morphology of all microorganisms (Fig 1). The simple stain uses the basic dyes such as Methylene blue or basic fuschin. The strong negative charge of the bacterial cell will strongly bind with the positive charged basic dyes and will impart its colour to all bacteria.
Fig 1: Simple staining of cocci
Gram staining is a differential staining technique that imparts different colours to different bacteria or bacterial structures. Usually it differentiates bacteria into two groups; gram positive and gram negative. The primary stain Crystal violet and mordent Iodine form a strong CVI complex all bacteria. Gram positive cells due to their thick peptidoglycan layer will retain the CVI complex even after it is subjected to decolourization with acetone or alcohol. Hence the counter stain Safranin has no action on gram positive cells. But in the case of gram negative, the thin peptidoglycan layer and more lipid contents in the cell wall will easily make them susceptible to the action of decolorizer and hence CVI complex is easily washed out and hence the gram negative cells will the colour of counter stain Safranin. Hence after the gram staining, the gram positive cells appear as purple and gram negative cells appear as pink (Fig 2). The study of morphological features and staining characteristics help in the preliminary identification of the isolate.
Gram negative enteric bacilli play an important role in the contamination of food. Hence they are the main causative agents of intestinal infection. Gram negative family includes Shigella, Salmonella, Proteus, Klebsiella,Escherichia,Enterobacter etc. Usually four tests are used for differentiation of the various members of Enterobactericeae. They are Indole test,Methyl red test, Voges proskauer test and Citrate test; collectively known as IMViC series of reactions.
Movement In Living Things Movement is one of the characteristics of all living beings.
Animals move in search of food, shelter, water, and many other purposes.
Learn about the different types of movement in animals such as:
Also learn about the skeletal system in animals, which helps in support and movement of animals.
All living organisms show movement in different ways. Though plants are fixed to the ground, they show movement too.
Learn about the movement in plants:
Coordination And Regulation In Living Organisms All the living organisms (plants and animals) respond and react to changes in the environment around them. The changes in the environment to which the organisms respond and react are called stimuli (singular of stimuli is stimulus). The living organisms show response to stimuli such as light, heat, cold, sound, smell, taste, touch, pressure, pain, water, and force of gravity, etc.
The response of organisms to a stimulus is usually in the form of some movement of their body part. For example, if a man touches a very hot utensil accidentally, he quickly pulls his hand away from the hot utensil. Here, heat is the stimulus and the man reacts by moving his hand away from the hot utensil. Similarly, when the sun is bright, we close our eyes. In this case, light is the stimulus and we reacting by closing the eyes.
Both, plants and animals react (or respond) to various stimuli around them. But the method of reacting to stimuli is not similar in plants and animals. They react to stimuli in different ways. For example, plants bend towards light but animals do not bend towards light. The animal Amoeba reacts to the presence of food by moving towards the food particle.
Similarly, Amoebae tend to aggregate (collect together) in moderately warm water which is their reaction to the stimulus called heat. Amoeba and other protozoal react to the mechanical obstacles by avoiding them. We find that the Amoeba (which is an animal) can react to different stimuli in different ways.
The animals can react to stimuli in many different ways because they have a nervous system and an endocrine system involving hormones. The plants, however, react to stimuli in a very limited way. This is because the plants do not have a nervous system like the animals have. The plants use only the hormones for producing reaction to external stimuli.
From all the above examples we conclude that when a stimulus acts on our body, then we react (or 1 respond) in a manner which is in the best interest of our body. The reaction (or response) which we give to the stimulus involves many organs of our body.
It is, therefore, necessary that all the concerned organs should work with one another in a systematic manner so as to produce the required reaction. In other words, the various organs should co-operate with one another to provide proper reaction to the stimulus.
The working together of the various organs of an organism in a systematic manner so as to produce a proper response to the stimulus is called coordination. We will now discuss the control and coordination in plants, animals and human beings, one by one. Let us start with control and coordination in plants.
Control and Coordination in Plants:
The plants do not have a nervous system and sense organs like eyes, ears, or nose, etc., like the animals, but they can still sense things. The plants can sense the presence of stimuli like light, gravity, chemicals, water, and touch, etc., and respond to them. The plants can sense things like light, gravity, chemicals, water, and touch, etc., by the action of hormones in them.
The stimuli like light, gravity, chemicals, water, and touch, etc., are called environmental changes. So, we can also say that the plants coordinate their behaviour against environmental changes by using hormones. The hormones in plants do not act the same way as in animals.
The hormones in plants coordinate their behaviour by affecting the growth of a plant. And the effect on growth of the plant can result in the movement of a part of the plant like shoot (stem) or root, etc.
Animals use both nervous system and hormones for coordination of their activities. Plants have no nervous system, so plants use only hormones for coordination. Thus, the reaction (or response) of plants to different stimuli like light, gravity, chemical substances, water, and touch etc., is due to the effect of hormones.
Control And Coordination In Living Organisms – Ii : Brief And Long Answers
The movement of curvature of plants in the direction of stimuli is known as tropism.
Phototropism : When illuminated by a unidirectional light, the response of agrowing plant by bending towards that light is called phototropism.
Geotropism : The downward movement of the roots of the plants, for fixation and absorption, as a response to the gravitational force is called geotropism.
Chemotropism : The movement of a plant or its part as a response to certain chemicals is called chemotropism. For example, germination of pollen grains and development of pollen tubes as a response to the chemicals secreted by the surface of the stigma.
The response by some plants to the external stimuli without any directional movement of growth or curvature towards that external stimuli is called nastic movement.
The leaves of Mimosa (touch-me-not) are sensitive to touch. They droop when touched.
All insectivorous plants bend down or curl up when touched by insects.
A sunflower plant bends towards the sun.
Of the above examples, (i) and (ii) are examples of thigmonastic response and (iii) is an example of photonastic response.
Distinguish between tropic movement and nastic movement.
Photoperiodism is the phenomenon in which the duration of light decides the flowering and germination in plants.
Plants are (i) Long-day plant and (ii) Short-day plant on the basis of the duration of light received by them.
Day natural plants do not respond to photoperiodism.
Plants respond to photoperiodic stimulus by a omplimenta pigment present in them called phytochrome.
Coordination in animals.
All multicellular organisms, except porifera, have well-developed nervous system.
Hydra and other cnidarians possess nerve cells which form a nerve net in the body.
In invertebrates, the nerve net condenses into nerve mass called ‘ganglion’.
Insects have a bilobed nerve mass (brain), nerve cord and nerve ganglia.
Higher organisms possess sensory organs (receptors) related to light, hearing, taste, touch and smell.
Receptors receive the stimulus and pass on the message to the brain through sensory neuron.
The brain transmits information to the effector organ (generally muscles and glands) through motor neuron.
The brain acts as the center for the analysis of information.
Motor neurons stimulate the muscles of the organ to respond.
Hormones also play an important role in control and coordination in animals.
In vertebrates there is a successive development of nervous system.
The nervous system of human beings is highly developed.
Hormones secreted by endocrine glands control various biochemical and mechanical activities carried out in the organisms. This is chemical control.
Write an explanatory note on human brain.
Human brain is the main coordinating center for all the activities of the human body.
It is protected by a bony box in the skull called cranium and three membranes calledmeninges.
There is a fluid called cerebrospinal fluid in the space between these membranes.
Cerebrospinal fluid acts as a cushion and protects the brain from mechanical shocks.
The brain is divided into three regions : (i) fore-brain (ii) mid-brain and (iii) hind-brain.
Fore-Brain consists of cerebrum and olfactory lobes.
Cerebrum is the most complex and omplimenta part of the brain.
It consists of two cerebral hemispheres.
It has sensory area to receive impulse from the sense organs and motor area to send impulse to muscles and effector organs.
Cerebrum has four regions having different centers of activity : (i) frontal lobe (ii) parietal lobe (iii) temporal lobe (iv) occipital lobe.
The frontal lobe possesses centres for voluntary muscular activities.
Parietal lobe possesses the centres for temperature control, smell and touch.
Temporal lobe possesses the centres for auditory and olfactory reception.
Occipital lobe possesses the centres for visual reception.
Mid-Brain is a part of the brain stem and possesses the regions for visual reception, auditory reception and touch.
Hind-Brain consists of cerebellum, pons and medulla oblongata.
Cerebellum is situated on the posterior side of the fore-brain and it controls the rhythmic movement of muscles, body balance and posture.
Pons connects various parts of the central nervous system and cerebellum by the transverse bands of nerves.
Pons takes part in the regulation of respiration and helps in the movement of head as per audio-visual perception in coordination with medulla oblongata and spinal cord.
Medulla oblongata possesses the centres to regulate heartbeats, breathing, blood-pressure, sneezing, coughing, vomiting, swallowing, hiccups, etc.
Spinal cord is a cylindrical structure.
It is the posterior extension of of medulla oblongata.
The vertebral column and meninges protect the spinal cord.
There are 31 pairs of spinal nerves arising from the spinal cord.
These nerves connect various organs of the body to the brain.
They help in the conduction of impulses from brain to organs and from organs to brain.
They also perform reflex action.
An unconscious and involuntary response of effectors to the stimulus is called reflex action.
Due to reflex action we suddenly withdraw our leg when we step on a very hot or pricking object.
Similarly, our response towards very hot or very cold water is sudden and involuntary.
The reflex action is performed by the spinal cord when the brain is busy or at rest.
In reflex action, a message from the receptors is relayed by sensory nerves to the spinal cord and the spinal cord sends response via motor nerve to the effector organ.
This entire pathway is called ‘Reflex Arc’.
Autonomous nervous system.
The system which is responsible for the intervention in the activities of the organs located in the body cavity without the awareness of brain is called autonomous nervous system.
This system controls heart, blood vessels, glands, uterus and coelomic organs.
Autonomous nervous system is of two types: (i) sympathetic (ii) parasympathetic.
The involuntary actions of the body are controlled and regulated by the coordination of these two systems.
The effects of sympathetic and parasympathetic nervous systems are complimentory and contradictory.
For example: If the sympathetic system increases the heartbeats abnormally, the parasympathetic system decreases it and brings it back to normal.
Characteristics of hormones.
They are specific chemical messengers.
Generally the origin and the target area of hormones are different.
They are directly poured into the blood (from the gland) and carried by blood circulation.
The effect of a hormone is either rapid or slow (i.e. it may increase or decrease the speed of some process). For example, acetylcholine increases the speed of the conduction of impulses whereas decreases (slows down) the effect of sex hormones.
Endocrine glands. Endocrine glands play an important role in coordination (in animals).
These are ductless glands and secrete hormones which are specific chemical messengers.
The main endocrine glands are hypothalamus, pituitary,, pineal, thyroid, parathyroid, pancreas, adrenal, testis and ovary.
Pituitary gland is called the master gland as it regulates the secretion of hormones by other endocrine glands.
The function of the pituitary gland is controlled by the secretion of hypothalamus.
How is brain protected ? The brain is surrounded by cranium, a bony box in the skull and three membranes called meninges. In the space between these membranes there is a fluid called cerebrospinal fluid. This fluid protects the brain against mechanical shocks. Thus brain is protected.