Higher Biology Revision Exercise Unit 1 Cell Biology

1. Higher Biology Revision Exercise Unit 1 Cell Biology

2. Cell Variety / Absorption and Secretion 1) The ____ is the basic unit of life. cell 2) A ___________ organism consists of one cell which possesses a variety of structures enabling it to perform all the functions necessary for the maintenance of life. unicellular 3) A ____________ organism consists of more than one cell. In advanced animals and plants these are arranged into tissues giving a division of labour. multicellular 4) _________ in cell structure exists between cells of one type of tissue and cells of different tissues since cells are __________ to perform particular functions. Variation specialised 5) Cells absorb molecules in solution by ________, osmosis and active _________. diffusion transport

3. 6) The cell wall surrounding plant cells is made of ________ and is ______ permeable to solutions. It prevents the cell from ________ when water is absorbed. cellulose freely bursting 7) The plasma __________ surrounding the living contents of all cells is selectively __________. It consists of protein and ____________ molecules thought to be arranged as in the fluid _______ model. membrane permeable phospholipid mosaic 8) Tiny channels in the plasma membrane make it _______ and allow the _______ transport of small molecules by diffusion and osmosis along a concentration gradient. porous passive 9) Other chemical substances such as ions are ________ transported across the plasma membrane _______ a concentration gradient by _______ carriers. This process requires _______. actively against protein energy

4. Respiration 1) _____ is a high energy compound able to release and _________ energy when it is required for cellular processes. ATP transfer 2) ATP is regenerated from _____ and inorganic phosphate by the process of _______________ using energy released during respiration. ADP phosphorylation 3) _________ involves the removal of hydrogen from a substrate and the release of energy; _________ involves the addition of hydrogen to a substrate and the consumption of energy. Oxidation reduction 4) _________ is a biochemical pathway common to aerobic and _________ respiration. It involves the breakdown of glucose to _______ acid in the cytoplasm of a cell with the net gain of two ATP. Glycolysis anaerobic pyruvic

5. 5) In the presence of ______, aerobic respiration occurs in the central ______ of mitochondria where the respiratory substrate is oxidised during ______ Cycle and _________ is released. oxygen matrix Krebs’ hydrogen 6) This hydrogen becomes temporarily bound to ____, a coenzyme which transfers it to the ___________ system on the cristae of ____________ where energy is released and used to form ATP. NAD cytochrome mitochondria 7) As a result of ________ respiration, one molecule of glucose yields 38 ATP. ______ and CO2 are the final metabolic products. aerobic Water 8) In the absence of oxygen, anaerobic respiration occurs and one molecule of glucose yields 2 ATP. The final metabolic products are ________ and ______________ in plant cells and _____ acid in animal cells (and some bacteria). ethanol carbondioxide lactic

6. Photosynthesis 1) Light is absorbed, reflected and ___________ by a leaf. transmitted 2) The photosynthetic pigments from a leaf can be separated by _______________. chromatography 3) Chlorophyll absorbs light primarily in the ____ and _____ regions of the spectrum of white light. _______ pigments absorb blue-green light. red blue yellow 4) The quantity of light absorbed by a pigment at different wavelengths of light can be presented as a graph called an __________ spectrum; the rate of photosynthesis that occurs in a plant at different wavelengths of light can be presented as a graph called an ______ spectrum. absorption action

7. 5) Chloroplasts possess internal structures called _______ which contain photosynthetic pigments and are the site of the ______________ stage of photosynthesis. The region between grana is called the _______. It is the site of the ______________ stage of photosynthesis. grana light-dependent stroma carbonfixation 6) The light-dependent stage of photosynthesis is called __________. It produces the energy (held in _____) and hydrogen needed for the second stage (carbon fixation). photolysis ATP 7) The second stage consists of a ______ of reactions which brings about the _________ of carbon dioxide using the ATP and _________ from photolysis to form carbohydrate. cycle reduction hydrogen 8) Photosynthesis is affected by temperature, light intensity and _____________ concentration. Its rate is therefore _______ by whichever one of these factors is in short supply. carbondioxide limited

8. DNA and its Replication / Protein Synthesis 1) DNA consists of two strands twisted into a double ________. Each strand is composed of ____________. Each nucleotide consists of ______________ sugar, phosphate and one of four types of base ( _________, thymine, _________ or cytosine). helix nucleotides deoxyribose adenine guanine 2) Adenine always pairs with _________; guanine always pairs with _________. thymine cytosine 3) DNA is unique because it is able to reproduce itself by ___________. This allows the genetic message to be passed on from cell to _____ and generation to generation. replication cell 4) RNA consists of a single strand of nucleotides. ________ is found in place of thymine; ________ replaces deoxyribose. Uracil ribose

9. 5) The bases along a DNA strand take the form of a molecular language called the genetic _____. Each _______ of bases codes for a particular amino acid. code triplet 6) Messenger RNA (mRNA) is ___________ from a strand of DNA and carries this genetic message from the nucleus out into the cytoplasm. At a _________, mRNA meets molecules of ________ RNA (tRNA) each carrying a specific amino acid. transcribed ribosome transfer 7) Protein synthesis occurs in ribosomes; mRNA’s triplet of bases, called _______, are read and matched by tRNA’s ___________. This enables peptide ______ to form between adjacent amino acids. codons anticodons bonds 8) Rough ____________ reticulum bears ribosomes on its outer surface. endoplasmic

10. 9) Freshly synthesised protein is transported via the endoplasmic reticulum to the ______ apparatus where it is processed and packaged in ________. Golgi vesicles 10) Some protein is _________ out of the cell by vesicles moving towards, and fusing with, the plasma membrane. secreted 11) In addition to carbon, hydrogen and oxygen, proteins always contain ________. nitrogen 12) A protein consists of sub-units called ____________ (of which there are about 20 types) joined together by peptide bonds to form polypeptides. aminoacids 13) A molecule of _______ protein consists of parallel ____________ chains and has a structural function. fibrous polypeptide

11. 14) A molecule of _________ protein consists of polypeptide chains folded into a spherical shape. Some are structural (eg. Those in the plasma membrane); others act as _________, hormones or __________. globular enzymes antibodies

12. Cellular Defence 1) ________ exhibit living and non-living characteristics and can only reproduce within the living cells of another organism. Viruses 2) A virus consists of one type of _______ acid surrounded by a coat of _______. nucleic protein 3) Once inside a host cell, the virus alters the _____ cell’s metabolism to produce many identical copies of itself. host 4) The two main ________ mechanisms employed by the human body depend on the activities of ______ blood cells. defence white 5) Phagocytes engulf and destroy microbes by ____________ using lysosomes. This is a ____________ response. phagocytosis non-specific

13. 6) _____________ recognise antigens on the surface of a microbe and produce ___________. These possess receptor sites which bind to one particular type of ________ rendering it harmless. This is a ________ immune response. Lymphocytes antibodies antigen specific 7) Plants do not make antibodies. They defend themselves against invasion by producing toxic compounds such as ________, cyanide and ________. nicotine tannins 8) Some plants can isolate an area of injury by secreting sticky ______. resin End