• 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…

  • Biology

    MCQ on Respiration in plant

    Q1) Out of 36 ATP molecules produced per glucose molecule during respiration(A) 2 are produced outside glycolysis and 34 during the respiratory chain.(B) 2 are produced outside mitochondria and 34 inside mitochondria.(C) 2 during glycolysis and 34 during the Krebs cycle.(D) all are formed inside mitochondria. Q2) Respiratory substrate yielding the maximum number of ATP molecule is(A) ketogenic amino acids(B) glucose(C) amylose(D) glycogen Q3) Fermentation is anaerobic production of(A) protein and acetic acid(B) alcohol, lactic acid or similar compounds(C) ethers and acetones(D) alcohol and lipoproteins Q4) In alcoholic fermentation(A) oxygen is the electron acceptor.(B) triose phosphate is the electron donor while acetaldehyde is the electron acceptor.(C) triose phosphate is the electron donor while…

  • Zoology


    In protozoans, porifers and coelenterates the specialised excretory structures are absent. The excretion in these animals occurs through the general body surface. The contractile vacuoles present in freshwater protozoans are the osmoregulatory structures and regulate osmotic concentration (osmolarity) of the body. Though some ammonia is also lost through contractile vacuoles, but they can not be considered as excretory structures. In Platyhelminthes (flatworms) the excretory structures are Protonephridia or Solenocytes. These structures are also present in Rotifers, Cephalochordates (Amphioxus). and some annelids. The tubules of protonephridia in flatworms terminate into Flame cells. These cells contain a tuft of cilia which project into the tubule and beat like flickering (candle) flame, hence…

  • Q & A on cytplasm
    Botony,  Q & A

    Q & A on living world and taxonomy

    https://youtu.be/VPvdSx18bk0 Q1. Who is known as the Darwin of the 20th centuryErnst Mayr(1940) – During the mid 20th century, Ernst Mayr was one of the ‘architects’ of the synthetic theory of evolution. He proposed Biological concept of species, on the basis of interbreeding Q2. In unicellular organisms the ……………. is synonymous with growth.In unicellular organisms like bacteria, amoeba and fungi reproduction of synonymous with growth. Growth is an increase in the size of organism and reproduction is giving rise to daughter organisms Q3. The sum of all chemical reactions occurring in our body is called .……..All living organisms are constantly making or breaking biomolecules. Such conversions are due to chemical…