Wednesday, 30 November 2011

Morphology of Flowering plants


  1. Name  the structure which protects the root tip.
  2. Name the root system that develops from any part of the plant body other than the radicle.
  3. Name the part of the plant which develops from the radicle in dicots.
  4. Name 2 aquatic plants with photosynthetic roots.
  5. Name two plant with fleshy adventitious roots.
  6. The 4 o'clock plant and sweet potato (Ipomoea batatas) are similar in one aspect and dissimilar in another aspect with reference to the nature and modification of roots. Write their difference.
  7. Name the roots which have indefinite shape.
  8. What is the name given to the modified stem of Opuntia?
  9. Name the phyllode with one internode.
  10. What is the main function of tendrils?
  11. Give an example of cladode.
  12. Thorn of Bougainvillea and the tendril of Cucurbita are homologous organs. How?
  13. Which plant parts has transformed into (a) tendril of pumpkin and (b) thorn of citrus?
  14. What takes over the function of photosynthesis in Opuntia?
  15. What kinds of stems are found in banana and Amorphophallus?
Answers:
  1. Root cap
  2. Adventitious root system
  3. Tap or primary root system
  4. Trapa and Tinospora
  5. Dahilia and sweet potato
  6. Both the plants have the tuberous roots but the roots in 4 O'clock plant are lobed and modified tap root while the roots of the sweet potato are modified adventitious roots and arise singly.
  7. Tuberous roots
  8. Phylloclade
  9. Cladode
  10. Tendrils help in climbing
  11. Asparagus
  12. Both develop from the axil of the leaf but perform different functions. The former gives protection while the latter helps in climbing.
  13. Both are modifications of stem
  14. The stem is modified into a thick, flattened leafy structure to carry out photosynthesis in Opuntia.
  15. Banana stem is a rhizome and Amorphophallus stem is a corm.

Tuesday, 29 November 2011

What is Living ?


The word living cannot be defined but Living things have a variety of common characteristics. Such characteristics distinguish the living from the non-living. They are as follows:

  1. Metabolism : The sum total of all the chemical reactions taking place in a living body is called metabolism. All living organisms are made up of small and large chemical compounds which carry out different functions. 
  2. Ability to Response: All organisms have the ability to sense the conditions in their surroundings and respond to these stimuli. Such stimuli may be physical, chemical or biological.
  3. Reproduction: Since all cells come from existing cells, they must have some way of reproducing, whether that involves asexual (no recombination of genetic material) or sexual (recombination of genetic material). Most living things use the chemical DNA (deoxyribonucleic acid) as the physical carrier of inheritance and the genetic information. Some organisms, such as retroviruses (of which HIV is a member), use RNA (ribonucleic acid) as the carrier. The variation that Darwin and Wallace recognized as the wellspring of evolution and adaptation, is greatly increased by sexual reproduction.
  4. Growth: Even single-celled organisms grow. When first formed by cell division, they are small, and must grow and develop into mature cells. Multicellular organisms pass through a more complicated process of differentiation and organogenesis (because they have so many more cells to develop).
  5. Organization. Living things exhibit a high level of organization, with multicellular organisms being subdivided into cells, and cells into organelles, and organelles into molecules, etc.
  6. Homeostasis. Homeostasis is the maintenance of a constant (yet also dynamic) internal environment in terms of temperature, pH, water concentrations, etc. Much of our own metabolic energy goes toward keeping within our own homeostatic limits. If you run a high fever for long enough, the increased temperature will damage certain organs and impair your proper functioning. Swallowing of common household chemicals, many of which are outside the pH (acid/base) levels we can tolerate, will likewise negatively impact the human body's homeostatic regime. Muscular activity generates heat as a waste product. This heat is removed from our bodies by sweating. Some of this heat is used by warm-blooded animals, mammals and birds, to maintain their internal temperatures.
  7. Adaptation. Living things are suited to their mode of existence. Charles Darwin began the recognition of the marvelous adaptations all life has that allow those organisms to exist in their environment
  8. Energy acquisition and release. One view of life is that it is a struggle to acquire energy (from sunlight, inorganic chemicals, or another organism), and release it in the process of forming ATP (adenosine triphosphate).
  9. Detection and response to stimuli (both internal and external).
  10. Interactions. Living things interact with their environment as well as each other. Organisms obtain raw materials and energy from the environment or another organism. The various types of symbioses (organismal interactions with each other) are examples of this. 

Monday, 28 November 2011

Circulatory Pathways Among Vertebrates

All vertebrate possess a muscular heart. They show 3 types of Circulatory Pathways : Single circulation, Incomplete double circulation and Double circulation.
frogs'heart 
fish's heart
  1. Single Circulation: Fishes show the single circulation pathway. Their hearts are 2-chambered with an atrium and a ventricle. The heart pumps out only deoxygenated blood to the gills for oxygenation. The oxygenated blood is supplied to all body parts and the deoxygenated blood from all the parts is returned to the heart.  
  2. Incomplete Double Circulation: Amphibians and the  Reptiles excluding crocodiles show the incomplete double circulation. The is 3 chambered with 2 atria and a ventricle. The left atrium receives oxygenated blood while the right atrium receives deoxygenated blood. But in single ventricle the oxygenated blood and deoxygenated blood get mixed up and that is pumped to all parts of the body.                   3. Double Circulation: Aves and Mammals show the double circulation. The heart is 4 chambered with 2 atria and 2 ventricles. The oxygenated and deoxygenated blood are completely partitioned from each other. The left auricle receives oxygenated blood, that passes into the left ventricle which pumps  it to all parts of the body. The right atrium receives deoxygenated blood from all the parts of the body that passes into the right ventricle which pumps it to the lungs for oxygenation. 


Sunday, 27 November 2011

Dr. Har Gobind Khorana

Khorana died of natural causes on November 9, 2011 in Concord, Massachusetts. He was 89. His wife died in 2001. Their daughter Emily Anne died in 1979. A widower, he was survived by his children Julia and Dave.
Har Gobind Khorana (January 9, 1922 – November 9, 2011) was an Indian-born American biochemist who shared the Nobel Prize in Physiology or Medicine in 1968 with Marshall W. Nirenberg and Robert W. Holley for research that helped to show how the nucleotides in nucleic acids, which carry the genetic code of the cell, control the cell's synthesis of proteins. He even devised a method to make several copies of DNA, which he termed “Repair Synthesis” that was later rediscovered by Kary Mullis and named as Polymerase Chain Reaction or PCR.
"Khorana was among the pioneers of the now-familiar series of three-nucleotide codons that signal to the cell which amino acids to use in building proteins - for example, uracil-cytosine-uracil, or UCU, codes for the amino acid serine, while CUC codes for leucine," said MIT News.

Look for Substitute

"Should Animal Dissection be Necessary in Classroom Practical?"
Animal dissection causes great suffering to the animal. The animal is treated merely as an object of study rather than a living thing. Firstly, we should have theoretical knowledge of the dissection through means such as television and computers with the guidance of a teacher. It is a better substitute for animal dissection.

{This thought was published in Science Reporter, April 2007 at page number 47 in the regular column titled Point Counterpoint}

Tuesday, 22 November 2011

It's Our Duty

"Do We Still Need Science Popularization Efforts in India Even After More Than 60 Years of Scientific Pursuit?"

It is said that nearly 50 percent of all the children are still deprived of access to even elementary education. In many cases the teaching methods and environment are so antiquated or poor that many children end up as mere dropouts. Today it is a knowledge-world and science and technology provide the means to fulfill the needs of globalization. Besides, our constitution declares that it shall be the duty of every citizen of India to develop the scientific temper and spirit of inquiry. In this context, we still need science popularization efforts.

{This thought was published in Science Reporter, August 2008 at Page No.-48 in the regular column titled Point Counterpoint }

Monday, 21 November 2011

The Importance Of Physical Fitness


Physical fitness is the part of true health. The true health is not the state of mere absence of diseases but a dynamic state of well-beings in terms of physical, mental and behavioural aspects of life. It is the pre-requisite to the success in life.
In every field of life the great men of the world possessed sound physical and mental fitness. If one searches for happiness, one will discover it coupled with the physical fitness. It is the best positive feature of humans. It is unique possession for the life. It is wealth. It makes life worth living. The importance of physical fitness cannot be described in words. Its necessity has become an inevitable feature of modern society.
It is all true. Humans are gifted with the faculty of reasoning and logical thinking. They are judicious creatures. Their dominance over other living things lies in their advanced brainpower. In fact, humans have been able to control Nature due to their highly developed intelligence or the brain. But, for the improvement of the mental power, it is indispensable that the body, too, should be hale and hearty.
‘A sound mind in a sound body’ is an oft quoted proverb. It emphasizes the importance of the physical fitness in our life. The mind can never be healthy, if the body is sick. The death of the body is the death of the mind; also. It is obvious that for intellectual development, the physical fitness is vital.
It is also important for the nation. Healthy and able-bodied citizens who bring athletic distinction to the nation at the international level are the priceless possession of a nation. In order to understand the importance of the physical fitness for a nation, the poignant words of the Father of the nation, Gandhi ji should be mentioned here. He said ‘India lives in the village and the strength of our nation depends upon the health of the rural folk, our richest heritage.’ Our country is not developed nation because of our effectiveness. Our effectiveness is very low in comparison to the effectiveness of the people of other country. When the effectiveness is low, the production cannot be increased and the prices cannot be lowered. So if we wish that the production of the country should be increased and consequently the goods should become cheaper, the fitness of the worker must be improved. Clearly, it has become the life-blood of the economy of a country. If we realize that the physical fitness is the noble wealth and maintain it, the whole earth will seem to be a paradise; otherwise the paradise will be lost.
The evolution of the living things and the creation of the variations are outcomes of the physical fitness. The theory of the survival of the fittest had its implication on the basis of physical fitness. The scientists know the value of physical fitness in the survival strategies of organisms ranging from smaller to the larger one. New diseases which are often a threat to us can be under the control only if we can develop the immunity against them. Undoubtedly, the physical fitness provides the power of resistance against diseases. This makes the need of physical fitness quite clear.
It is well known that our government is spending lakhs and lakhs of rupees for providing medical facilities. It is busy in fighting various diseases to make society free of them. But medical facilities alone can never solve this problem. It is also well known that diseases attack only those who lose their vitality and vigour. People with sound health may live even in poverty, but they never fail ill. So our people need physical exercises if they want to have disease free bodies.
Our body is thought to be made up of five elements: earth, water, fire, air and sky. Actually these are the things which are needed to survive in this world. We need the most fertile earth or soil for cultivation of the food grains and other objects of uses. We need clean water for drinking and performing other functions in which it is required. Similarly, fresh light, fresh air and open sky are also needed for our survival. Deficiency of any of those elements of life may cause our extinction. An ideal state of all above five elements is the state of the physical fitness.
For the students, its importance becomes many folds. Students have to do several mental works and to sit for long hours during studies. All these require energy and proper training for maintenance of good body postures. Otherwise, their posture becomes defective. They can neither sit nor stand properly. Their body begins to look very gauche. The backside does not remain upright but develops a curvature. Thus their spinal columns get ill-treated. So for our educational institutions, the management for physical exercise is very important. It is the only way; the students can maintain their health. For this very reason, other persons also, who carry on deskbound activities, must take some physical exercise each day.
Our forces need more and more young man with stout physical condition. Once our late Pandit Nehru said, “Every child of India shall have to be a soldier of freedom.” Only people with sound health who are sparkling over with heroism and patriotism can fight for their country’s sovereignty. It is only through physical fitness.
In our country the rate of infant mortality is quite high. The weak health of the parents is its main reason. Sick and diseased parents can reproduce only feeble and unhealthy offspring. The parents must be healthy, if they want to have healthy children. They must take some physical exercise daily.
Morning walk is good for health. It is the best form of exercise that keeps our body fit and active. It costs nothing yet it is very useful for our health. Those who live in towns and cities must take morning walk to get fresh air and energy. It makes us healthy and strong. It refreshes our mind. It strengthens our body. It saves us form many disease. It improves our digestion. We feel a good appetite after a long walk. It is equally good for the young and the old. It keeps us fresh for the whole day. It develops in us a good habit of rising early. It awakens in us love for nature. So it keeps us fresh healthy and energetic. Hence, it is of great advantages to us.
To be healthy we keep our houses clean. It should be well ventilated. It must get light from the sun. Our food plays an important part in the constitution of our health. It is a fuel for the body. In order to be healthy, food must be balanced. Besides these, body needs exercises. Regular exercise keeps us active. Rest after work is also necessary.
To be brief, for the individual as well as the social point of view physical fitness is very crucial. It is the constitutive ingredient of contentment. It makes our life fascinating, significant, intense and worth living. Even in paucity, one can enjoy peace and satisfaction much more than those of the rich. An exercise is the only way to maintain the physical fitness besides Yoga. Mental, emotional and physical development of the people can continue efficiently only if they take physical exercises. So, wherever possible, physical exercises must be made unavoidable.