Unit - 1

Introduction

Q1) Explain Biology as a scientific discipline?

A1) Biology is the branch of natural science that deals with studies of life and living organisms, that include their physical structure, chemical process, molecular interactions, physiological mechanisms, development and evolution. Despite the complex involved in the science, there are certain concepts that consolidate it into a single, coherent field. Biology assumes the cell as the basic unit of life, genes as the basic unit of heredity, and evolution as the engine that propels. The creation and extinction of species.

Biology derives its word from the ancient Greek words of βίος; Romanisedbios meaning "life" and -λογία; Romanisedlogia (-logy) meaning "branch of study" or "to speak".  Those combined make the Greek word βιολογία; Romanisedbiología meaning biology (Study of Life).  All sciences are equally important in that they all expand our collective understanding of the universe in different areas.

That being said, there is a varying level of difficulty associated with different sciences when we get past the basics. The advanced concepts in physics, like general relativity and quantum mechanics require a very high level of fluency in mathematics that the other sciences. Even the greatest physicists have claimed to have difficulty understanding the implications of these complex theories.  However, we can understand the most complicated concepts in biology using only one language, like English or German. In order to fully understand physics or math, we must also learn the language of mathematics at its highest level.  Thus, biology does not make it any more or less important but it definitely adds a whole new level of study and discovery.

Q2) Mention the fundamental differences between camera and eye?

A2) The camera and the human eye have many things in common than just conceptual philosophy -- the eye captures images similar to the way the camera does. The anatomy of the camera has more similarities to a biological eyeball than anyone would imagine, including the lens-like cornea and the film-like retina. These similarities give the camera the appearance of a robotic eye. However, though there are many similarities between cameras and eyes, they are by no means identical.

Cornea and Lens

The cornea is the “cap” of the eye. This transparent (like clear jelly) structure sits to the front of the eye and has a spherical curvature. The lens of a camera is also transparent (glass) and sits at the front of the body. Like the cornea, the lens also maintains a spherical curvature. The corneal and lens curvature allows the eye and camera to view, though not in focus, a limited area to both the right and the left. That is, without the curve, the eye and camera would see only what is directly in front of it.

Iris and Aperture

The aperture is to the camera as the iris is to the eye, and this reveals one of many similarities between cameras and the eyes. The aperture size refers to how much light is let into the camera and will ultimately hit the sensor or film. As with the human eye, when the iris contracts itself, the pupil becomes smaller and the eye takes in less light. When the iris becomes wide in dark situations, the pupil becomes larger, so it can capture more light. The same effect occurs with the aperture; larger (lower) aperture values allow lighter than a small (higher) aperture value. The lens opening is the pupil; the smaller the opening, the less light is allowed inside.

Focus in Eyes and Cameras

Both the eye and camera have the tendency to focus on one single object and blur the rest of the object, whether in the foreground (shallow depth of field) or away at a distance. Likewise, the eye can focus on a larger image, just as a camera (greater depth of field) 

Scope and Field of View

As the eye, the camera also has a limited scope to capture what is around it. The curvature of the eye and the lens of the camera allow both to take in what is not directly in front of it. However, the eye can capture in a fixed scope, while a camera's scope can be changed using the focal length of different types of lenses.

Retina and Film

The retina is present at the back of the eye and collects the light reflected from the surrounding environment to form the image. A similar task in the camera is performed either by film or sensors in digital cameras. This process underpins both how cameras work and how eyes work

Q3) Explain the Brownian motion with examples?

A3) Brownian motion is the random, movement of particles that cannot be controlled in a fluid as they constantly collide with other molecules (Mitchell and Kagura, 2006). Brownian motion is thus a part responsible of the ability of movement in bacteria that do not encode or express motility movements, such as Streptococcus and Klebsiella species. Brownian motion can also affect “deliberate” movement exhibited by naturally motile bacteria that harbour pili or flagella. For example, an Escherichia coli cell that is swimming toward an area of higher oxygen concentration may fall “off-track” if it physically encounters a particle moving by Brownian motion or if such a particle(s) obstructs the bacterial cell’s path of motion. This form of “interference” adds to the stochasticity with which bacterial direction can change.

Brownian motion takes its name from the Scottish botanist Robert Brown, who observed pollen grains moving randomly in water. He described the motion in 1827 but was unable to explain it. While pedes is takes its name from Brown, he was not the first person to describe it. The Roman poet Lucretius describes the motion of dust particles around the year 60 B.C., which he used as evidence of atoms.

Examples include:

• The motion of pollen grains on still water
• Movement of dust motes in a room (although largely affected by air currents)
• Diffusion of pollutants in the air
• Diffusion of calcium through bones
• Movement of "holes" of electrical charge in semiconductors

Q4) Explain two major discoveries of the 18th century?

A4) French scientist Louis Pasteur performed experiments on the use of microorganisms in fermentation and early vaccination procedures, and invented the process of pasteurization, in which heat is used to kill microorganisms found in food products. In his studies, Pasteur disproved the notion of spontaneous generation, showing that microorganisms can only arise from other microorganisms. Pasteur also developed the first vaccines.

Alexander Fleming, professor of bacteriology, Fleming noticed that a culture plate of Staphylococcus aureus he had been working on had become contaminated by a fungus. A mold, later identified as Penicillium notatum (now classified as P. Chrysogenum), had inhibited the growth of the bacteria. He at first called the substance “mould juice” and then “penicillin,” after the mold that produced it. Fleming decided to investigate further, because he thought that he had found an enzyme more potent than lysozyme. In fact, it was not an enzyme but an antibiotic—one of the first to be discovered, the therapeutic development of penicillin required multidisciplinary teamwork. However, he did point out that penicillin had clinical potential, both as a topical antiseptic and as an injectable antibiotic, if it could be isolated and purified.

Q5) Draw a comparison between the flying bird and the Aircraft?

A5) Birds and Aircraft use the same principle to fly. Both aircraft wings and bird wings have a basic air foil shape with both top and bottom sides cambered but with the upper chamber is more pronounced than the bottom. Air moving above the wings moves faster than the air below creating a pressure difference that lifts the wing but to do this, air has to move over the wing. Aircraft do this using engine, the jet engines or propellers, create thrust that overcome the plane's inertia, aerodynamic drag and accelerate it till enough air is moving over the wings surfaces to create lift the, birds on the other hand use their powerful flight muscles attached to an enlarged sternum to flap their wings. The flapping motion is in a swimming fashion where the wings fold and sweep forward during the upstroke and spread out and flap down with a slight backwards sweep to create thrust and lift. Some birds make a running take off to get some speed while others jump from heights to utilise gravity to get the required starting momentum. When the birds are gliding the aerodynamics are exactly similar. All wings work by bending the air downwards and exert a force equivalent to the force that the weight of the bird or aircraft exerts on the air.

When birds flap their wings they provide a rearward propulsive force, similar to when human beings swimming using butterfly stroke and this is combined with the downward bending of the air around the wing, Airplanes are fixed wing structures that rely on an independent source of thrust (engines, or wind in the case of gliders).

Birds generate thrust by flapping their wings up and down. This would be a very complicated and inefficient method for airplanes to use, perhaps even impossible. Both airplanes and birds control the pitch (climbing or descending movement) by a similar method. The tail of the bird is same as the horizontal stabilizer of an airplane. By forcing or applying pressure on the rear end up or down the wings will either point more up or more down making the bird or aircraft climb up or descend down.

But airplanes have a tail that is vertical for controlling the yaw (left-right orientation) of the airplane. Birds in contrast perform this function by twisting their horizontal tail in one direction or the other (clockwise or counter clockwise about the central axis of the bird). This pushes their rear end to the right or left keeping them pointed in the right direction. Large birds soaring in a high wind have shown this behaviour. So, birds unlike airplanes control their pitch and yaw with a single control surface (the tail). It is really quite amazing and humbling to see how skilfully they manoeuvre with a tail.

Q6) Why do need to study Biology?

A6) Biology is the study of life and living things through rigorously-tested and peer-reviewed scientific research.  Biology has evolved as a field of science since it was studied in ancient civilization although modern biology is a relatively recent field. Modern biology is a very vast and eclectic field that has many specialized disciplines that study the growth, structure, function, evolution, distribution or other features of living beings.

Biology helps individuals understand the interaction between humanity and the world. It also develops interests in the lives of living organisms in an effort to preserve them. Through studying biology, pathologists understand the human body, the functions of various organs, how diseases affect the body and ways to effectively control diseases,

Biology plays an important role in the understanding of complex forms of life involving humans, animals and plants. Understanding these intricate details of life helps humans understand how to care for themselves, animals and plants in the proper manner. Biology helps individuals understand the interaction between humanity and the world. It also develops interests in the lives of living organisms in an effort to preserve them. Through studying biology, pathologists understand the human body, the functions of various organs, how diseases affect the body and ways to effectively control diseases. Veterinarians have to study biology to appreciate the functions of animals, including marine animals and creatures that live on land. Environmentalists rely on the study of biology to learn how man’s actions affect his surroundings and the ecosystems of other living beings.

Studying biology is the foundation of all characteristics of life on Earth. Apart from creating solutions to the challenges many living organisms face, it paves the way for inventions and discoveries that improve the quality of life. Without studying biology, humans would probably never realize how important maintaining a healthy ecology is for themselves, animals and plant life. Additionally, studying biology enables the use of forensics to trace and arrest errant members of the society. It also allows agriculturalists to rear unique breeds of plants and animals.

Q7) Highlight the features of Scientific enquiry?

A7) Scientific inquiry indicates to the various ways in which scientists study the natural world and suggested explanations based on the evidence derived from their experimental work. The steps involved in a scientific inquiry are as follows:

• Observation
• Question
• Hypothesis
• Experiment
• Results
• Conclusion

The initial fundamental importance to define and describe Brownian motion was that it supports the modern atomic theory. In the recent days, the mathematical models that describe Brownian motion are used in physics, economics, engineering, math, chemistry, biology, and a host of other disciplines.

Mayer was also the first person to propose the vital chemical process which is now referred to as oxidation which is the primary source of energy for all living creature. This relation implies that heat and work are identical to each other and are present in various forms of energy which can be transformed. This law was known as the first law of the caloric theory and led to the formulation of the general principle of conservation of energy. 

Q8) With Reference to Thermodynamics explain Meyer’s and Robert observation?

A8) A brief account of microscopical observations made in the August, 1827, by Robert brown on the particles contained in the pollen of plants; and on the general existence of active molecules in organic and inorganic bodies" He suspended some of the pollen grains of the species Clarkia pulchella in water and examined them closely, only to see them “filled with particles” of around 5 µm diameter that were “very evidently in motion”. He was soon satisfied that the movement that was observed in pollen grains “arose not from currents in the fluid or from its gradual evaporation, but belonged to the particle itself”. Brown’s work was the first comprehensive observation of a phenomena called Brownian Motion which remained unexplained until the beginning of the 20th century by Bachelier and most notably by Einstein in his famous paper in 1905. Brownian motion is the most basic description of the dynamics of a particle, price, etc. under the influence of external noise. 

Julius Robert von Mayer was a German physician and physicist. He was the first to state the Law of the Conservation of Energy: energy is neither created nor destroyed. He stated that the sun is the ultimate source of energy for both plants and animals and that when absorbed plants convert this light energy to chemical energy through the process of photosynthesis. "The plants take in one form of power, light; and produce another power: chemical difference." He used the term ‘power’ for energy and ‘chemical difference’ for chemical energy. He therefore made it clear that plants do not only produce organic matter but also provide the energy which sustains life.

Thus the Brownian motion is one of the characteristic examples used to illustrate the present approaches to stochastic thermodynamics, considerable effort has been made to identify thermodynamic quantities like heat, work, entropy at the level of a single Brownian particle, on the other hand Julius Mayer is best known for his original statements on the conservation of energy which is now known as the First law of thermodynamics, namely that energy can neither be created nor destroyed. Therefore, the discoveries of Robert Brown and Julius Mayer formed the basis for thermodynamics.

Q9) Biology as a science of life? Explain.

A9) It is the scientific study of life, and similar to life, biology is a rich and diverse field of study? Just like the living organisms it focuses on, the versatility and ever-changing making it a study subject that is full of excitement, beauty and wonder. Biologists study life at various levels, from the tiniest of cells, and organisms to entire ecosystems.

Biology is the science of life. The name is derived from the Greek words "bios" (life) and "logos" (study). Biologists study the structure, function, growth, origin, evolution and distribution of living organisms. Biology is a vast field that is generally considered to have at least nine "umbrella" fields of biology, each of which consists of multiple subfields.

• Biochemistry:  it deals with the study of the material substances that make up living things
• Botany:  is the study of plants, including agriculture
• Cellular biology: it deals with the study of the basic cellular units of living things
• Ecology: It consists of the study of how organisms interact with their environment
• Evolutionary biology: it is the study of the origins and changes in the diversity of life with time
• Genetics: it deals with the study of heredity
• Molecular biology: is the study of biological molecules present in living beings
• Physiology:  it deals with the study of the functions of organisms and their parts
• Zoology: the study of animals, including behaviour of Animals

Adding to the complexity of this enormous fields, is the fact that they overlap. It is however impossible to study zoology without knowing a great deal about evolution, physiology and ecology.

All the branches that are included in biology can be summarised within a framework of five basic understandings about living things. Studying the details of these five ideas provides the endless fascination of biological research:

• Cell Theory: There are three parts to cell theory — the cell is known as the basic unit of life, all living things are composed of cells, and all cells arise from pre-existing cells.
• Energy: All living things need energy, and energy flows between organisms and also between organisms and the environment.
• Heredity:  It deals with living things that have DNA and genetic information codes the structure and function of all cells.
• Equilibrium: It’s a condition of all living things that must maintain homeostasis, a state of balanced equilibrium between the organism and its environment.
• Evolution: Is the overall unifying concept of biology. Evolution is the change over time that is the engine of biological diversity.

Q10) Explain the Watson and Crick model?

A10) Watson and Crick discover chemical structure of DNA. Though DNA–short for deoxyribonucleic acid –was discovered in 1869, its crucial role in determining genetic inheritance wasn’t demonstrated until 1943. In the early 1950s, Watson and Crick were only two of many scientists working on figuring out the structure of DNA.

In 1953, J.D. Watson (an American biologist) and F.H.C. Crick (a British Physicist) proposed the three-dimensional model of physiological DNA (I. e B-DNA) on the basis of X-ray diffraction data of DNA obtained by Franklin and Wilkins. For this epoch-making discovery, Watson, Crick and Wilkins got Nobel Prize in medicine in 1962. Term DNA was given by Zaccharis.

The important features of Watson – Crick Model or double helix model of DNA are as follows:

1. The DNA molecule consists of two polynucleotide chains or strands that spirally twisted around each other and coiled around a common axis to form a right-handed double-helix.

2. The two strands are antiparallel i.e., they ran in opposite directions so that the 3′ end of one chain facing the 5′ end of the other.

3. The sugar-phosphate backbones remain on the outside, while the core of the helix contains the purine and pyrimidine bases.

The two strands are held together by hydrogen bonds between the purine and pyrimidine bases of the opposite strands.

5. Adenine (A) always pairs with thymine (T) by two hydrogen bonds and guanine (G) always pairs with cytosine (C) by three hydrogen bonds. This complimentarily is known as the base pairing rule. Thus, the two stands are complementary to one another.

6. The base sequence along a polynucleotide chain is variable and a specific sequence of bases carries the genetic information.

7. The base compositions of DNA obey Chargaff s rules (E.E. Chargaff, 1950) according to which A=T and G=C; as a corollary ∑ purines (A+G) = 2 pyrimidines (C+T); also (A+C) = (G+T). It also states that ratio of (A+T) and (G+C) is constant for a species (range 0.4 to 1.9)

A hypothetically untwisted DNA lie flat to show ladder like appearance. The two sides of the ladder are called the DNA’s backbone, the steps inside the ladder represent the base pairs.

8. The diameter of DNA is 20nm or 20 A. Adjacent bases are separated 0.34 nm or by 3.4 A along the axis. The length of a complete turn of helix is 3.4 nm or 34 A i.e., there are 10bp per turn. (B- DNA-Watson rick DNA)

9. The DNA helix has a shallow groove called minor groove (-1,2nm) and a deep groove called major groove (- 2.2nm) across.