• Q & A on cytplasm

    Q & A on Components of Cytoplasm

    Which organelle divides and compartmentalizes the cell?  The endomembrane system, which fills the cell and divides it into compartments, and is visible only through electron microscopy. The endoplasmic reticulum (ER), a series of interconnected membranous tubes and channels in the cytoplasm, is the largest and most extensive system of the internal membranes. What is the function of the endomembrane system? The endomembrane system allows macromolecules to diffuse or be transferred from one of the components of the system to another. What is the difference between rough and smooth endoplasmic reticulum? Rough endoplasmic reticulum are regions rich in ribosomes that manufacture proteins. These regions appear to have a pebbly surface that is somewhat similar to sand-paper.…

  • Zoology

    Phylum Hemichordata

    Phylum Hemichodata Hemichordates are vermiform, solitary or colonial enterocoelous coelomate animals having intra-epidermal nervous system and a pre-oral gut with or without gillslits and without typical nephridia. Due to some similarities with chordates, some workers (Bateson, 1885) considered Hemichordata as a subphylum of the phylum Chordata. Alliance with the chordates was based on the presence of gill slits and the so called ‘notochord’. It is now generally agreed that the hemichordate “notochord” is neither analogous nor homologous with the chordate notochord and that except the common possession of pharyngeal clefts the two groups are dissimilar. On grounds of its similarities with invertebrates some recent scientists, like Van der Horst (1939),…

  • MCQ

    MCQ on Breathing and Exchange of Gases

    Dead space air is  The amount of air left in lungs after deepest expiration.  About 150 ml  Both of these  None of these Answer: 2 The amount of air left in the lungs after the deepest expiration is Residual air.  2. When fully saturated, one molecule of oxyhaemoglobin carries the following number of oxygen molecules.  Two  Three  Four  None of these  Answer: 3 One molecule of Haemoglobin contains four molecules of Haem, so four iron atoms, for carrying for molecules of Oxygen 3.Which of the following breathing process in human is passive  Expiration Aspiration  Inspiration  Forced breathing  Answer: 1 4. The amount of oxygen in tidal vol. is approximately  1…

  • Flashcard,  Genetics

    Genetics Terms Flashcard

    Genetics Genetics is the study of inheritance and variation. Term genetics was first used by W. Bateson 1905. Gregor Johann Mendel is called the father of genetics. Heredity or inheritance Heredity or inheritance is the process by which characters are passed on from parent toprogeny Variation Variation is the characteristic difference by which progeny differs from their parents. Cause of variation is sexual reproduction. Phenotype External appearance or trait of an individual. Genotype Genetic constitution of an organism Genes or mendelian factor Units of inheritance. They contain the information required to express a particular trait Alleles or allelomorphs The two Mendelian factors or gene which occur on the same locus…

  • Diffusion
    Cell biology,  O level biology

    Diffusion – Movement of Substances

    Table of Contents Diffusion Defination Diffusion is the net movement of molecules and ions from a region of their higher concentration to a region of their lower concentration down a concentration gradient, as a result of their random movement. What is Diffusion  The molecules of a gas such as oxygen are moving about all the time. So are the molecules of a liquid or a substance such as sugar dissolved in water. As a result of this movement, the molecules spread themselves out evenly to fill all the available space (Figure). Diffusion This process is called diffusion. How are substances transported by diffusion? One effect of diffusion is that the…