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Paramecia are often described as slipper shaped. Paramecium caudatum is 150 to 300 µm in length and is blunt anteriorly and somewhat pointed posteriorly. The organism has an asymmetrical appearance because of the oral groove, a depression that runs obliquely backward on the ventral side. The pellicle is a clear, …

The Euglenozoa is generally considered a monophyletic group, based on the shared persistence of the nucleoli during mitosis, and the presence of discoid mitochondrial cristae. Members of this phylum have a series of longitudinal microtubules just beneath the cell membrane that help to stiffen the membrane into a pellicle. The …

The Geographic Grid  It is impossible to lay a flat sheet of paper over a sphere without creasing, folding, or cutting it—as you know if you have tried to gift-wrap a ball. This simple fact has caused mapmakers problems for centuries. Because the Earth’s surface is curved, we cannot divide …

বেঁচে থাকার জন্য একটা সুন্দর জীবনের স্বপ্ন সবাই দেখে। জীবনের সমস্ত শিকলের বেড়াজাল ছিন্ন করে মানুষ স্বাধীনভাবে নিজেদের মতো করে বাঁচতে চায়। সব অত্যাচারের বিরুদ্ধে একদিন তারা সংঘবদ্ধ হয়ে লড়াই করে। কিন্তু সমতার লড়াইয়ের যুদ্ধে জয়লাভের পর নিজেদের মধ্যে যে স্বার্থের দ্বন্দ্ব শুরু হয়, তার প্রকোপ কেমন হয়! সাম্যের গন্ডি …

বইয়ের নামটার সাথে পুরো উপন্যাসটার পরতে পরতে যেন লেখক মায়াজাল বিস্তার করে রেখেছেন। ভিঞ্চি মানে লিওনার্দো দ্য ভিঞ্চি!! বিশ্বখ্যাত এই চিত্রকর এর নাম বোধহয় কমবেশি সবাই শুনেছে। তিনি বিখ্যাত তার লা-জকোন্দা বা AMONLISA বা O Lame Saint!! এর জন্য। বুঝতে কষ্ট হচ্ছে তাইনা! এই তিনটা নামই আমাদের সুপরিচিত একটা বিখ্যাত …

The Shape of the Earth  As we all learn early in school, the Earth’s shape is very close to a sphere. Pictures taken from space by astronauts and by orbiting satellites also show us that the Earth is a ball rotating in space.   Today it seems almost nonsensical that …

Reproduction Sexual phenomena occur widely among protozoa, and sexual processes may precede certain phases of asexual reproduction, but embryonic development does not occur; protozoa do not have embryos. The essential features of sexual processes include a reduction division of the chromosome number to half (diploid number to haploid number), the …

Vacuoles can be seen by light microscopy in the cytoplasm of many protozoa. Some of these vacuoles periodically fill with a fluid substance that is then expelled. Evidence is strong that these contractile vacuoles function principally in osmoregulation. They are more prevalent and fill and empty more frequently in freshwater …

Nucleus As in other eukaryotes, the nucleus is a membrane-bound structure whose interior communicates with the cytoplasm by small pores. Within the nucleus the genetic material (DNA) is borne on chromosomes. Except during cell division, chromosomes are not usually condensed in a form that can be distinguished, although during fixation …

A cilium or flagellum has considerable internal structure. Each flagellum or cilium contains nine pairs of longitudinal microtubules arranged in a circle around a central pair and this is true for all motile flagella and cilia in the animal kingdom, with a few notable exceptions. This “9+ 2” tube of …