The Science of Biology

Biology is the science devoted to the study of living objects. Two Greek words, bios (life) and logos (discourse), explain the term "biology" as meaning study of living creatures. Since life manifests itself in various forms i.e. plant and animal forms, biology is the study of both. The study of plants is termed as botany or plant biology, while the study of animals is called zoology or animal biology.

Biology also comprises of the cellular basis of living things for the activities of life. It consists of energy metabolism and also of genetics which forms the basis of inheritance in organisms. Living things have been studied since primitive times. Primitive man had to find out what could be utilized for food, shelter and clothing, which plants would be useful as medicines and which animals he could use to get work done for him. The science of biology thus arose out of basic human needs.

Biology also includes evolutionary relationships between organisms. Biology tells us about the routine activities of microorganisms, plants and animals and also the relation between their structures and functions. Many sub-divisions and special areas of biology exist but biology can conveniently be divided into two categories, (A) Practical and (B) Theoretical.

• Practical biology consists of plant breeding, medical science, wildlife management, agriculture.
  
• Theoretical biology consists of Physiology (the study of the functions of living things), Microbiology (the study of microscopic organisms), Biochemistry
  
  (the study of the chemical makeup of organisms), Ecology (the study of populations and their environment) and Taxonomy (categorization).
  1.1 Practical Biology
  
  Introduction
  
  Living things are made up of cells which form the basic unit of life. The cell is, in turn, made up of molecules and atoms. The cell usually cannot be seen with the naked eye. Each cell performs certain functions. Some functioning cells come together organize to form a tissue. It is at this stage that the complex structuring of living things begins. A group of tissues, when organized, form organs such as the brain, the heart, etc. When a number of organs work together, they compose an organ system. So an organism is a composite union of various organ systems. The combination of several organisms is called population, which, in turn, forms a community, leading to the creation of a Biosphere. Figure 1.1 represents the structural complexity of the Biosphere.
  i) Metabolism
  
  An organism is basically made up of six basic elements: C, H, O, N, P and Ca. These make up about 96% of the weight of an organism. To keep life intact there is an exchange of chemical matter from cell to environment and environment to cell. Organic matter from the environment is absorbed by the cell and utilized for preparing energy. The energy thus prepared is used to perform the functions of the cell. Unlike in nonliving things, a number of physical and chemical changes take place in the body of the organism. The sum total of physical and chemical changes in an organism is called metabolism. Metabolism includes anabolism in which complex organic substances are built up and energy is stored, and catabolism in which the complex organic substances are broken down to release energy. These changes of conservation and release of energy continuously take place in the organism. This energy is basically in the form of chemical energy. Nonliving matter does not show this kind of exchange of energy.
  
  
  ii) Growth
  
  In metabolism we have seen that organic matter is collected from the environment and processed in the cell. In the process of growth, the cell organizes this material into its own structure. During growth the cell spends some amount of the energy created in the process of metabolism. Every organ has its own pattern of growth. This pattern depends upon the tissue of the organ. Growth of different organs leads to physical growth. Food is converted into organic matter which is then utilized for the growth of the body. Nonliving organisms do not show these characteristics.
  iii) Reproduction
  
  A living thing has the ability to procreate when it matures through the process of reproduction. There are differences in the reproductive functions of higher animals and lower animals. In lower animals (as in unicellular animals like amebas and bacteria), reproduction merely extends the process of growth. For instance, after maturity, a single bacterium splits into two bacteria, in six stages. This process is called asexual reproduction. In asexual reproduction only one parent is involved. So generally the produced cells are identical to the parent cell. In asexual reproduction, the rate of production of offspring is faster than in sexual reproduction. In higher or more complex organisms there is another type of reproduction called sexual reproduction. In sexual reproduction, two parents of opposite gender type are responsible for the formation of a new organism. During sexual reproduction, a new combination of genetic material (D.N.A.) occurs. This process is complex and takes more time than asexual reproduction. Nonliving things do not reproduce. 
  iv) Responsiveness to Stimuli
  All living things are able to respond to stimuli in the external environment. Stimuli originate from different sources.
  a) physical: light, heat, temperature, sound.
  b) chemical: acids and alkali.
  c) mechanical: friction, pressure.
  
  The body has specialized tissue or higher centers to detect stimuli, such as eyes for light, ears for auditory stimuli, the nose for olfactory stimuli, the tongue for taste, the skin for touch, etc.
  An organism must co-ordinate well to give an appropriate response to the stimuli from the environment. All systems of the body help in this co-ordination, like nerves from the nervous system, and certain chemical regulators called hormones from the endocrine system. This simultaneously produces an effect of co-ordination and acts as a sensing system. To respond to the stimuli, the organism has certain efferent units like muscles, glands, hair, etc. The process of response involves the use of energy.
  The responses are of two types:
  a) generalized, and
  b) protective.
  
  Protective responses help to promote survival and thus sustain life. A generalized response contribute to the behavior patterns of an organism. For certain classes, the response occurs with a definite pattern which is innate to the organism.
  Nonliving things don’t respond to stimuli as living things do.
  
  v) Evolution
  Living organisms normally interact with the environment for their daily requirements. There are always changes going on in the environment. To adapt to these changes, there are genetic changes in the animal. The process of adaptation in a new generation animal in the population is called evolution. Evolution allows for changes in interactions between the organism and its environment. The evolved organism is more capable of adapting to changes in the environment. This adaptation in the organism leads to the formation of a new species and also newer organisms within the species. So with evolution, a new species is formed but certain characteristics from the previous generation remain intact.
  vi) Ecology
  Ecology is the study of the relationships between the environment and the organism, and between various organisms . Due to interaction with the environment, the organism and its environment continuously influence each other. Animate organisms can migrate to another place if the environment is not suited to their survival in a given region. For instance, frogs cannot live in water if there are too many crocodiles on their side of the pond. Nonliving things cannot change their environment. 
   

  Scientific Methodology

  
    
  To study the sciences, including biology, a person must adopt a certain manner of thinking about questions, The methods used to answer questions about biology require a scientist to think about all the possibilities that could explain an observation. The scientist then refers to the research that other scientists and experts have done which might help him or her to better understand the problem. Then experiments are designed which will rule out all the possibilities except one. If all possibilities except one are ruled out, then the remaining possibility must be true explanation. Scientific method consists of the following steps.
  i) Observation
  The scientist objectively ( without forming opinions yet) observes a particular phenomenon in nature or in the laboratory. A problem based on that observation is declared. The scientist then formulates the required steps to solve the problem. Because other scientists may also be working on this same problem or similar problems, the scientist must use the library to read about what others have already discovered. This is necessary to help design experiments that have already been done by others.
  ii) Hypothesis, Experimental Inference, and Analysis
  This next step is to form a hypothesis, which is a simple statement that is either true or false. For example, a scientist may except that water is necessary to keep houseplants alive. He might form the hypothesis, " water is necessary for houseplants to remain alive," which is either true or false. The parameters of the experiment would include houseplants with water, and houseplants without water. The experiment is repeated several times. In this case, the scientist could merely observe the state of the plant ( dead or alive). In other experiments, the hypothesis might require that actual measurements would be made, such as the height of the plant, the number of leaves formed, etc.
  iii) Conclusion
  
  Based on the outcome of the experiments and whether the hypothesis was found to be true or proven to be false, an inference is drawn,. In our example, the houseplants without water would turn brown and die, so the scientist would infer that water is necessary to keep houseplants alive. Therefore, our hypothesis that " water is necessary for houseplants to remain alive" would be supported ( i.e., not proven to be incorrect). This, and other experiments which show that water is necessary for discoveries are also discussed at scientific converences.
  iv) Theory and Law
  
  If many different experiments are performed which all support a hypothesis, then it is likely to actually be true. If most scientist have high confidence that a hypothesis to be true, then it is now considered to be a theory. Theories are hypotheses that are assumed to be true. If a theory is tested and retested in many ways, and no evidence can be found that proves that it is not true, then it is eventually considered to be a fact of nature, and is referred to as a "law"..
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