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Transcript
Higher Biology Revision Exercise Unit 1 Cell Biology Cell Variety / Absorption and Secretion 1) The ____ cell is the basic unit of life. 2) A ___________ unicellular organism consists of one cell which possesses a variety of structures enabling it to perform all the functions necessary for the maintenance of life. 3) A ____________ multicellular organism consists of more than one cell. In advanced animals and plants these are arranged into tissues giving a division of labour. 4) _________ Variation in cell structure exists between cells of one type of tissue and cells of different tissues since cells are __________ specialised to perform particular functions. 5) Cells absorb molecules in solution by ________, diffusion osmosis and active _________. transport 6) The cell wall surrounding plant cells is made of ________ cellulose and is ______ freely permeable to solutions. It prevents the cell from ________ bursting when water is absorbed. 7) The plasma __________ membrane surrounding the living contents of all cells is selectively __________. permeable It consists of protein and ____________ phospholipid molecules thought to be arranged as in the fluid _______ mosaic model. 8) Tiny channels in the plasma membrane make it _______ porous and allow the _______ passive transport of small molecules by diffusion and osmosis along a concentration gradient. 9) Other chemical substances such as ions are ________ actively transported across the plasma membrane _______ against a concentration gradient by _______ carriers. This process requires _______. protein energy Respiration 1) _____ ATP is a high energy compound able to release and _________ transfer energy when it is required for cellular processes. 2) ATP is regenerated from _____ ADP and inorganic phosphate by the process of _______________ phosphorylation using energy released during respiration. 3) Oxidation _________ involves the removal of hydrogen from a substrate and the release of energy; _________ reduction involves the addition of hydrogen to a substrate and the consumption of energy. 4) Glycolysis _________ is a biochemical pathway common to aerobic and _________ respiration. It involves the breakdown of glucose to _______ anaerobic pyruvic acid in the cytoplasm of a cell with the net gain of two ATP. 5) In the presence of ______, oxygen aerobic respiration occurs in the central ______ of mitochondria where the respiratory substrate is oxidised matrix during ______ Krebs’ Cycle and _________ hydrogen is released. 6) This hydrogen becomes temporarily bound to NAD ____, a coenzyme which transfers it to the ___________ cytochrome system on the cristae of ____________ where energy is released and used to form ATP. mitochondria 7) As a result of ________ aerobic respiration, one molecule of glucose yields 38 ATP. ______ Water and CO2 are the final metabolic products. 8) In the absence of oxygen, anaerobic respiration occurs and one molecule of glucose yields 2 ATP. The final metabolic products are ________ and ______________ ethanol carbon dioxide in plant cells and _____ lactic acid in animal cells (and some bacteria). Photosynthesis 1) Light is absorbed, reflected and ___________ transmitted by a leaf. 2) The photosynthetic pigments from a leaf can be separated by _______________. chromatography 3) Chlorophyll absorbs light primarily in the ____ red and _____ blue regions of the spectrum of white light. _______ yellow pigments absorb blue-green light. 4) The quantity of light absorbed by a pigment at different wavelengths of light can be presented as a graph called an __________ absorption spectrum; the rate of photosynthesis that occurs in a plant at different wavelengths of action spectrum. light can be presented as a graph called an ______ 5) Chloroplasts possess internal structures called _______ grana which contain photosynthetic pigments and are the site of the ______________ light-dependent stage of photosynthesis. The region between grana is called the _______. stroma It is the carbon fixation stage of photosynthesis. site of the ______________ 6) The light-dependent stage of photosynthesis is called __________. photolysis It produces the energy (held in _____) ATP and hydrogen needed for the second stage (carbon fixation). 7) The second stage consists of a ______ cycle of reactions which brings about the _________ reduction of carbon dioxide using the ATP and _________ hydrogen from photolysis to form carbohydrate. 8) Photosynthesis is affected by temperature, light intensity and _____________ carbon dioxide concentration. Its rate is therefore _______ limited by whichever one of these factors is in short supply. DNA and its Replication / Protein Synthesis 1) DNA consists of two strands twisted into a double ________. helix Each strand is composed of ____________. nucleotides Each nucleotide consists of ______________ deoxyribose sugar, phosphate and one of four types of base ( _________, adenine thymine, _________ guanine or cytosine). 2) Adenine always pairs with _________; thymine guanine always pairs with _________. cytosine 3) DNA is unique because it is able to reproduce itself by ___________. replication This allows the genetic message to be passed on from cell to _____ cell and generation to generation. 4) RNA consists of a single strand of nucleotides. ________ Uracil is found in place of thymine; ________ ribose replaces deoxyribose. 5) The bases along a DNA strand take the form of a molecular language called the genetic _____. code Each _______ triplet of bases codes for a particular amino acid. 6) Messenger RNA (mRNA) is ___________ transcribed from a strand of DNA and carries this genetic message from the nucleus out into the cytoplasm. At a _________, ribosome mRNA meets molecules of ________ transferRNA (tRNA) each carrying a specific amino acid. 7) Protein synthesis occurs in ribosomes; mRNA’s triplet of bases, called _______, codons are read and matched by tRNA’s ___________. anticodons This enables peptide ______ bonds to form between adjacent amino acids. 8) Rough ____________ endoplasmic reticulum bears ribosomes on its outer surface. 9) Freshly synthesised protein is transported via the endoplasmic reticulum to the ______ Golgi apparatus where it is processed and packaged in ________. vesicles 10) Some protein is _________ secreted out of the cell by vesicles moving towards, and fusing with, the plasma membrane. 11) In addition to carbon, hydrogen and oxygen, proteins always contain ________. nitrogen 12) A protein consists of sub-units called ____________ amino acids (of which there are about 20 types) joined together by peptide bonds to form polypeptides. 13) A molecule of _______ fibrous protein consists of parallel ____________ polypeptide chains and has a structural function. 14) A molecule of _________ globular protein consists of polypeptide chains folded into a spherical shape. Some are structural (eg. Those in the plasma membrane); others act as _________, enzymes hormones or __________. antibodies Cellular Defence 1) ________ Viruses exhibit living and non-living characteristics and can only reproduce within the living cells of another organism. 2) A virus consists of one type of _______ nucleic acid surrounded by a coat of _______. protein 3) Once inside a host cell, the virus alters the _____ host cell’s metabolism to produce many identical copies of itself. 4) The two main ________ defence mechanisms employed by the human body depend on the activities of ______ white blood cells. 5) Phagocytes engulf and destroy microbes by ____________ phagocytosis using lysosomes. This is a ____________ non-specific response. 6) _____________ Lymphocytes recognise antigens on the surface of a microbe and produce ___________. antibodies These possess receptor sites which bind to one particular type of ________ antigen rendering it harmless. This is a ________ specific immune response. 7) Plants do not make antibodies. They defend themselves against invasion by producing toxic compounds such as ________, nicotine cyanide and ________. tannins 8) Some plants can isolate an area of injury by secreting sticky ______. resin End