General Biology: Definitions and explanations page 13 PDF Book

Learn general biology terms with definitions and explanations, biology terminologies (Page 13) for biology degree programs.


  1. What is Photosystem?
    Photosystems are functional and structural units of protein complexes involved in photosynthesis. there are two photosystems ...
  2. What is Phototropism?
    Phototropism is the growth of an organism in response to a light stimulus. phototropism is most ...
  3. What is Phyllotaxy?
    Phyllotaxy is the arrangement of leaves on a plant stem. phyllotactic spirals form a distinctive class ...
  4. What is Phylogenetic species concept?
    This concept of a species describes species as an irreducible group whose members are descended from ...
  5. What is Phylogeny?
    A phylogenetic tree or evolutionary tree is a branching diagram or "tree" showing the evolutionary relationships ...
  6. What is Physiology?
    Physiology is the scientific study of the functions and mechanisms which work within a living system. ...
  7. What are Phytochromes?
    Phytochromes are a class of photoreceptor in plants, bacteria and fungi use to detect light. they ...
  8. What is Phytoremediation?
    Phytoremediation refers to the technologies that use living plants to clean up soil, air, and water ...
  9. What is Pilli?
    Pilli, like fimbriae are also hair like appendages present on some types of prokaryotic cells. these ...
  10. What is Pineal gland?
    The pineal gland is a small endocrine gland in the brain of most vertebrates. the pineal ...
  11. What is piRNA?
    Piwi-interacting rna (pirna) is the largest class of small non-coding rna molecules that are expressed in ...
  12. What is Pith?
    Pith, or medulla, is a tissue in the stems of vascular plants. pith is composed of ...
  13. What is Placenta?
    The placenta is a temporary organ that connects the developing fetus via the umbilical cord to ...
  14. What is Plant cortex?
    A cortex is an outer layer of a stem or root in a plant, lying below ...
  15. What are Plasma cells?
    Plasma cells are white blood cells that secrete huge volumes of antibodies. they are moved by ...
  16. What is Plasma membrane?
    The interior of the cell is protected from the exterior of the cell by this membrane. ...
  17. What is Plasma?
    Blood plasma is a yellowish liquid component of blood that normally holds the blood cells in ...
  18. What are Plasmids?
    A plasmid is a small, circular, double-stranded dna molecule that is distinct from a cell's chromosomal ...
  19. What is Plasmodesmata?
    Much like the cell junctions in the animal cells, plasmodesmata in the plant cells help them ...
  20. What is Plasmogamy?
    Plasmogamy is a stage in the sexual reproduction of fungi, in which the cytoplasm of two ...
  21. What is Plasmolysis?
    When the cells are present in a hypertonic environment, they shrink as the water moves out ...
  22. What is Plastid?
    Plastids is the generic name given to specialized organelles that present in plants and have the ...
  23. What are Plate tectonics?
    Plate tectonics is the theory that earth's outer shell is divided into several plates that glide ...
  24. What are Platelets?
    Platelets, also called thrombocytes and they are a component of blood that function along with the ...
  25. What is Pluripotent?
    Pluripotent cells are able of give rise to several different cell types. pluripotent cells can be ...
  26. What is Poikilotherm?
    A poikilotherm is an animal whose internal temperature varies considerably. it is the opposite of a ...
  27. What are Point mutations?
    A point mutation is a mutation that only affects a single nucleotide of nucleic acid. point ...
  28. What is Polarity of epithelia?
    The apical surface faces the lumen (cavity) or outside of the organ and is therefore exposed ...
  29. What is Polarity?
    Polarity is a fundamental property of biological systems. polarity is defined as the persistent asymmetrical and ...
  30. What is Pollen grain?
    Pollen is a fine to coarse powdery feeling substance that consists of pollen grains. these grains ...
  31. What is Pollination?
    Pollination is the transfer of pollen from a male part of a plant to a female ...
  32. What is Poly A tail?
    Polyadenylation is the addition of a poly(a) tail to a messenger rna. the poly(a) tail consists ...
  33. What is Polygenic inheritance?
    Polygenic inheritance occurs when one characteristic is controlled by two or more genes. often the genes ...
  34. What is Polymer?
    A polymer is a large macromolecule that is made of several repeating subunits. an example of ...
  35. What is Polymerase chain reaction?
    A technique used to amplify the number of dna copies present in a sample. sometimes the ...
  36. What is Polyploidy speciation?
    By definition, polyploidy just means that a cell or organism contains more than 2 pairs of ...
  37. What is Polyploidy?
    Polyploidy is the state of a cell or organism having more than two paired sets of ...
  38. What is Polyps?
    A polyp is one of two forms found in the phylum cnidaria, the other being the ...
  39. What are Polyribosomes?
    A polyribosome is a complex of an mrna molecule and two or more ribosomes that act ...
  40. What are Polysaccharides?
    Polysaccharides are polymeric carbohydrate molecules composed of long chains of monosaccharide units bound together by glycosidic ...
  41. What is Population?
    Population is the number of living this that inhabit an area. the individuals belonging to a ...
  42. What is Positional information?
    A widely used mechanism for pattern formation in many animals, is based on positional information. cells ...
  43. What is Positive feedback?
    Positive feedback is a process in which the end products of an action cause more of ...
  44. What is Positive pressure breathing?
    Positive pressure breathing is inflating the lungs with forced airflow. intermittent positive pressure breathing (ippb) is ...
  45. What is Post translational modification?
    After translation of a peptide, certain amino acids may be chemically modified by the attachment of ...
  46. What are Postzygotic barriers?
    Postzygotic reproductive barriers occur after the zygote has formed which mean they either reduce the viability ...
  47. What is Potential energy?
    Potential energy is the energy held by an object due to its relative position to other ...
  48. What are Preprophase bands?
    The preprophase band is a microtubule array found in plant cells that are about to undergo ...
  49. What is Pressure potential?
    Unlike ψs, ψp can be positive or negative relative to atmospheric pressure. for example, when a ...
  50. What is Prezygotic barrier?
    Prezygotic barriers typically act in one of three ways. firstly, by impeding members of different species ...
  51. What is Primary growth?
    In simple terms, primary growth is the increase in length of the shoot and the root ...
  52. What is Primary transcript?
    The initial transcript made by transcription is called as the primary transcript. it is still in ...
  53. What is Primase?
    Primase is the enzyme that synthesis the primer. the dna replication cannot just begin on its ...
  54. What are Prions?
    A prion is a type of protein that can trigger normal proteins in the brain to ...
  55. What are Producers?
    Primary producer, is an organism that produces complex organic compounds (such as carbohydrates, fats, and proteins) ...
  56. What are Prokaryotic cells?
    A prokaryote is a unicellular organism that lacks a membrane-bound nucleus, mitochondria, or any other membrane-bound ...
  57. What is Promoter?
    A promoter is a sequence that is present in the start of a gene sequences or ...
  58. What is Prophage?
    A prophage is a bacteriophage genome inserted and integrated into the circular bacterial dna chromosome or ...
  59. What is Protease?
    A protease is an enzyme that helps proteolysis which is the process of protein catabolism by ...
  60. What are Protein domains?
    A protein domain is a conserved part of a given protein sequence and (tertiary) structure that ...