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152 Cards in this Set
- Front
- Back
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How does hydrogen bonding occur between water molecules? |
There is a low electron density in the H atoms and a high density in the O atom, causing the H20 molecule to become polarised. The H+ ends are attracted to O- ends of other molecules and form hydrogen bonds |
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What is the structure of an amino acid? |
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How is a peptide bond formed? |
The OH from the hydroxyl group and a hydrogen from the amine group react to produce water, the C and the N that the OH and H have left behind then bond with eachother with a peptide bond. It is a condensation reaction. |
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Define primary structure and state the types of bonding that occur |
Specific sequence of amino acid Peptide bonds |
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Define secondary structure and state the types of bonding that occur |
Primary structures coiled or folded to from alpha helices or beta pleated sheets. Hydrogen bonds |
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Define tertiary structure and state the types of bonding that occur |
Secondary structures coiled or folded further to form a specific 3D shape. Hydrogen bonds, ionic bonds, disulphide bonds, hydrophillic/hydrophobic interactions |
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What is the structure of haemoglobin? |
A globular quaternary structure. 4 tertiary structures joined together with H bonds, each with a haem group, which can hold 4 Fe+ ions. |
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Define quaternary structure and give examples of some quaternary structures |
2 or more protein structures joined together Haemoglobin, collagen |
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What is the structure of a collagen molecule? |
3 polypeptide chains of proline, alanine and glycine wrapped around eachother to form a rope-like structure. Hydrogen bonds form between each rope. Covalent bonds between the ends of each rope |
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What type of protein is collagen? |
Fibrous |
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What type of protein is haemoglobin? |
Globular |
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What is the structural difference between alpha and beta-glucose? |
Alpha glucose has H above and OH below Beta glucose has OH above and H below |
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What is the structure and function of starch (amylose)? |
Highly branched polysaccharide chains Energy storage in plants |
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What is the structure and function of cellulose? |
(Up to 10,000) Beta glucose bonded together into long chains. Found in plant cell walls, gives the plant structure. |
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How does the structure of starch make it suitable for its function? |
Highly branched - lots of ends to be broken down by enzymes into glucose for respiration -densely packed, doesn't take up a lot of space Insoluble -doesn't affect the water balance of the cell |
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How does the structure of cellulose make it suitable for its function? |
Chains form H bonds and form microfibrils and macrofibrils. These are very very strong, makes it suitable for strengthening plant cells. Also insoluble, so doesn't affect water balance of the cell |
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What is the test for protein? |
Biuret reagant test
Turns lilac in the presence of protein |
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What is the test for reducing sugars? |
Bendicts test
Add excess Benedict's solution, heat to 80 degrees celcius, the degree of colour change from blue through to red will tell you how concentrated it is |
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What is the test for starch? |
Iodine solution
Will turn blue/black in presence of starch |
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What is the test for lipids? |
Emulsion test
Add ethanol and a small amount of water and shake. It will form a cloudy white emulsion in the presence of a lipid |
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How can the concentration of glucose in a solution be determined using calorimetry? |
Produce a calibration curve from calorimetry results from Benedict's tests of known concentrations Compare the result for unknown concentration with curve Read off graph |
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What is DNA? |
Deoxyribose Nucleic Acid Polynucleotide, double stranded, made up of nucleotides |
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What is a nucleotide? |
A molecule consisting of a deoxyribose sugar molecule, a nitrogenous bade and a phosphate head |
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What are the nitrogenous bases for DNA? |
Adenine (A), Thymine (T), Cytosine (C) and Guanine (G) |
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What are the nitrogenous bases for RNA? |
Adenine (A), Uracil (U), Cytosine (C) and Guanine (G) |
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How is RNA different to DNA? |
- The sugar molecule that makes up the nucleotides in RNA is ribose -The nitrogenous base uracil (U) is found instead of thymine (T) -It is single stranded -There are three forms; -mRNA -rRNA -tRNA |
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Which base pairs are complementary? |
A and T, C and G |
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What are the two DNA polynucleotides in the double helix described as being? |
Antiparallel |
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How does DNA replicate semi-conservatively? |
Unwinds and unzips (helicase) Free nucleotides line up with their complementary base pairs and bond DNA polymerase bonds together the sugar-phosphate backbone Recoils New DNA has one old strand and one new |
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What are the roles of RNA molecules in living organisms? |
mRNA -Copies genes and carries them to ribosomes, to give them instructions to code for proteins tRNA -Brings specific amino acids to the ribosome in the right order, according to the instructions provided by the mRNA
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What are enzymes? |
Globular proteins with a specific tertiary structure, which catalyse metabolic reactions in living organisms |
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Is enzyme action intracellular or extracellular? |
Both |
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What effect does pH have on enzyme activity? |
Enzymes will have a specific pH where their activity is highest. Above and below their optimum pH, enzyme activity will decrease because the imbalance of H+ and OH- ions causes the bonds in the tertiary structure to be disrupted, resulting in a change in the shape of the active site, and the substrate no longer being complementary- the enzyme is denatured. |
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What effect does enzyme concentration have on enzyme activity? |
When enzyme concentration is at 0, enzyme activity is at 0. As enzyme concentration increases, enzyme activity increases because a successful collision between enzyme and substrate is more likely. Eventually the enzyme activity will reach vMax because all active sites will be occupied, so the rate of reaction can't increase any further. |
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What effect does temperature have on enzyme activity? |
When temperature is at 0, enzyme activity is at 0. As temperature increases, so does enzyme activity because the increased kinetic energy increases the chances of successful collisions between enzymes and substrates. It continues to increase until it reaches its optimum temperature (~40 deg). Higher than this, and the enzymes will denature because the bonds in their tertiary structures will get broken, the tertiary structure will change and their active sites will no longer be complementary to the substrate. |
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What are competitive inhibitors and what do they do? |
They are molecules that have a similar shape to the substrate molecules, and can therefore fit into and block the entrance to the active site, preventing the substrate from binding to the enzyme. They can reduce the rate of reaction. |
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What are non-competitive inhibitors and what do they do? |
They are molecules which attach to the allosteric site on the enzyme and cause the shape of the active site of the enzyme to change by distorting the enzyme's tertiary structure. They reduce the rate of reaction because substrate molecules are no longer complementary to the active site, so they can't bind together. |
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What are co-factors and what effect do they have on enzyme-controlled reactions? |
Ions which make the binding of the enzyme-substrate complex form more easily. They increase the rate of reaction |
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What are co-enzymes and what effect do they have on enzyme-controlled reactions? |
Organic non-protein molecules that bind to the active site for a short period of time. They may be altered in the reaction, but they are recycled. They are used to make enzyme controlled reactions occur in a particular order. |
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What happens if you are poisoned with ethylene glycol (antifreeze)? |
The liver breaks down the antifreeze and produces oxalic acid which is extremely toxic and can prove fatal. Ethanol is used as an antidote- the ethanol acts as a competitive inhibitor for the antifreeze, preventing the liver from breaking it down. |
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How can enzyme inhibition be used to our advantage? |
Some medicines work by inhibiting enzymes The antidote to antifreeze poisoning uses alcohol as a competitive inhibitor |
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Define balanced diet |
A diet that contains the proper proportions of carbohydrates, fats, proteins, vitamins, minerals, and water necessary to maintain good health. |
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How can an unbalanced diet lead to obesity? |
If you consume more calories (take in more energy) than you burn off, the excess energy is deposited as fat. Excessive fat deposits cause obesity |
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How does a poor diet lead to CHD (coronary heart disease)? |
Excess salt leads to a lower water potential of the blood, this can cause hypertension, which leads to artherosclerosis Excess cholesterol (LDLs especially) can lead to artherosclerosis |
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What effects can high blood cholesterol have on the heart and circulatory system? |
Can cause artherosclerosis, which can lead to strokes and heart attacks |
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What are HDLs and LDLs- what is the difference? |
HDLs are high density lipoproteins. They carry cholesterol from the tissues to the liver to be broken down. 'Good' cholesterol. LDLs are low density lipoproteins. They carry cholesterol from the liver to the tissues. High levels of LDLs in the blood can cause deposition in the arteries. 'Bad' cholesterol. |
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How can selective breeding be used in industry? |
To produce crop plants with high yields, disease resistance and pest resistance To produce domestic animals with high productivity |
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How does selective breeding work? |
Breed the best crops/animals together over several generations to eventually get the optimum result 1. Isolation 2. Artificial selection 3. Inbreeding |
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How can the use of fertilisers and pesticides with plants increase food production? |
They make the plants grow more quickly and healthily, increases their chance of survival which increased yield |
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How can the use of antibiotics with animals increase food production and what are the risks? |
Can make the animals grow faster. It's problematic because they can develop antibiotic resistance which limits the number of antibiotics available to use |
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What are the advantages and disadvantages of using micro-organisms to make food? |
Advantages -No cholesterol or animal fat -Faster to produce -No animal welfare issues -Can be grown on waste Disadvantages -Less palatable (doesn't taste nice) -People might not like the concept of it -Risk of contamination of the fungus |
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How does salting/adding sugar prevent food spoilage? |
Draws water out of cells and kills bacteria |
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How does pickling prevent food spoilage? |
Vinegar is acidic, this denatures the enzymes working to decay the food |
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How does freezing prevent food spoilage? |
Slows down enzyme activity so the food goes off more slowly |
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How does heating/cooking prevent food spoilage? |
High temperature denatures the enzymes in bacteria |
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How does irradiation prevent food spoilage? |
Disrupts the DNA of the micro-organism |
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How is health defined? |
Your physical, mental and social wellbeing |
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Good health means you are: |
-Free from disease -Able to carry out the normal physical and mental tasks expected in modern society -Well fed, with a balanced diet -Suitably housed -Well integrated into society -Usually happy |
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Define disease |
A malfunction of the body or mind, which causes symptoms |
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What are some examples of parasites? |
Head lice Tapeworms |
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How can parasites cause harm? |
Depriving their host of nutrition Causing damage to the host, allowing other organisms to invade and cause secondary infections |
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What is a pathogen? |
An organism that causes disease |
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How can bacteria cause disease? |
They damage cells and release waste products that are toxic to us |
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What are some examples of diseases caused by bacteria, and the bacteria that cause them? |
Cholera- bacterium Vibiro cholerae Tuberculosis- bacteria Mycobacterium tuberculosis and Mycobacterium bovis |
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What is the causative agent of TB? |
Mycobacterium tuberculosis |
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How can fungi cause disease? |
When it sends out reproductive hyphae, these grow to the surface of the skin to release spores. These cause redness and severe irritation |
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What are some examples of species of fungi? |
Microsporum, trichophyton, epidermophyton, tinea |
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What are some examples of disease caused by fungi? |
Athlete's foot Ringworm |
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How can viruses cause disease? |
They invade cells and take over genetic machinery and organelles of the cell. They then hijack the cell to make it make more copies of the virus, which eventually causes the cell to burst. This damages cells. |
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What are some examples of diseases caused by viruses? |
The common cold Influenza HIV/AIDS |
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How do protoctista cause disease? |
They enter host cells and feed on their contents as they grow |
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What are some examples of diseases caused by protoctista? |
Malaria Amoeboid dysentery |
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How do protoctista cause disease? |
They enter host cells and feed on their contents as they grow |
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What are some examples of diseases caused by protoctista? |
Malaria Amoeboid dysentery |
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What is the causative agent of malaria? |
The plasmodium genus |
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Why are HIV, malaria and TB most common in sub-Saharan Africa and other developing countries? |
-Limited access to good healthcare; --drugs are not always available --people are less likely to be diagnosed and treated --surgical equipment isn't always sterile -limited health education -limited equipment to prevent the spread -overcrowded conditions |
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What are the body's primary defences? |
Skin - a physical barrier against pathogens -also produces chemicals which prevent the growth of pathogens
Mucous membranes -protect body openings -secrete mucus that traps pathogens
Stomach acid -kills bacteria in the digestive system |
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Outline the stages of phagocytosis |
1) Phagocyte recognises antigens on a pathogen 2) Cytoplasm moves around pathogen, engulfing it in a phagocytic vacuole 3) Lysosome fuses with phagocytic vacuole 4) Lysosomal enzymes break down the pathogen 5) Phagocyte presents the pathogen's antigens to activate other immune system cells |
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What are antibodies? |
Proteins produced by plasma cells to help to fight infection |
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What are the different parts of an antibody called? |
Variable regions Constant regions Hinge region Disulphide bridges Heavy chains & light chains |
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What is the function of the hinge region of an antibody? |
Allows flexibility when the antibody binds to the antigen, so that it can bind to more than one antigen at once |
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What is the function of the constant region of an antibody? |
Allows binding to the receptors on immune system cells, e.g. phagocytes |
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What is the function of the variable region of an antibody? |
Allows binding to the antigens- the shape of the variable region is specific and complementary to the antigen |
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How do antibodies help to clear an infection? |
Agglutinating pathogens (clumping pathogens together by binding to more than one pathogen at once) which allows phagocytes to engulf many pathogens at once
Neutralising toxins (by binding to the toxins produced by the pathogens) so that phagocytes can engulf them |
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What is a T-lymphocyte? |
A type of white blood cell that binds to antigens being presented by phagocytes |
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What is a B-lymphocyte? |
A type of white blood cell that bind to antigens and form an antigen-antibody complex |
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Where are T-lymphocytes made and matured? |
Made in the bone marrow Matured in the thymus gland |
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Where are B-lymphocytes made and matured? |
Made in the bone marrow Matured in the bone marrow |
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Outline the roles of T-lymphocytes and what they do in the immune response |
They are activated when they bind to a complementary antigen being presented by a phagocyte. Once activated, they divide (clonal expansion) and differentiate (clonal differentiation) into different types of T-cells which have different functions |
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Outline the roles of B-lymphocytes and what they do in the immune response |
B-cells are activated when the antibodies on their surface bind to complementary antigens. They then divide by mitosis into plasma cells and memory cells |
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What is the surface of a T-lymphocyte covered in? What is the surface of a B-lymphocyte covered in? |
T-cells are covered in receptors B-cells are covered in antibodies |
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How is cell signalling used in the immune response? |
Cells may release a substance which binds to receptors on another cell, which causes some kind of response, e.g. the activation of a lymphocyte |
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What are memory cells and what do they do? |
Memory cells are lymphocytes which stay in the blood after a pathogen has been defeated. They stay in the blood stream until they encounter the pathogen, at which point they are activated and divide rapidly into either the correct T-cells to kill it or plasma cells to produce the right antibodies. |
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What is the difference between the primary and secondary immune response? |
The primary response is when the pathogen enters the body for the first time. It is slow and activates B and T cells. You would show symptoms after the primary response.
The secondary response is the second time- it is much faster and only activates memory cells, which deal with the pathogen. You would not show symptoms after the secondary response. |
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What is active immunity? Give an example |
The type of immunity that is acquired when the immune system makes its own antibodies after being stimulated by an antigen
E.g. catching a disease, having a vaccination |
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What is passive immunity? Give an example |
The type of immunity that is acquired from being given antibodies made by another organism's immune system
E.g. recieving antibodies across the placenta as a fetus, being injected with antibodies for tetanus |
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Why is the primary response slow? |
-There aren't many B-cells that can make the required antibody -By the time enough B-cells have been made, you will have shown signs of disease -Differentiation and reproduction of T-cells and B-cells takes time |
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How can vaccination control disease? |
They contain antigens that cause your body to produce memory cell against a particular pathogen, without the pathogen causing disease. If most members of a population are vaccinated, it reduces the spread of disease because people who are unprotected are less likely to catch it (there's no-one to catch it from) |
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Why do new vaccines for influenza have to be developed every year? |
Every year there are different strains of the virus circulating- they may have different antigens to the old strains, so older vaccinations are ineffective |
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NEED TO DO SMOKING FLASHCARDS |
OK |
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How does the structure of haemoglobin differ from that of collagen? |
Haemoglobin has a prosthetic group known as haem, collagen has no prosthetic group Collagen is made from 3 polypeptides, haemoglobin is made from 4 Haemoglobin has 2 alpha chains and 2 beta chains, collagen has 3 alpha chains |
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What are the differences in the structures of starch (amylose) and cellulose? |
Amylose is coiled, cellulose has no coiling Amylose is made from alpha-glucose, cellulose is made from beta-glucose Amylose is not fibrous, cellulose is fibrous Amylose has all monomers in the same orientation, cellulose has alternate monomers at 180 degrees |
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Why is the ability of water to act as a solvent important for the survival of organisms? |
Many metabolic reactions occur when reactants are in the form of aqueous solution Allows ionic compounds to separate Acts as a transport medium Allows transport of minerals in the xylem |
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How many hydrogen bonds form between C and G and A and T? |
3 between C and G 2 between A and T |
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Why is DNA replication considered to be semi-conservative? |
New molecule has one old strand and one new strand Original strand acts as a template |
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Why is complementary base-pairing important in DNA replication? |
Stops mutation because original strand acts as a template Makes the new strand an exact copy- identical DNA |
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What is a dichotomous key? |
A key with questions which only have yes/no answers |
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Why is the influenza virus described as a pathogen rather than a parasite? |
Pathogen causes disease (not all parasites cause disease) and influenza causes disease Parasite gains nutrition from host- influenza virus doesn't gain nutrition from host Virus takes over genetic material |
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Define immune response |
Response to an antigen involving lymphocytes and the production of antibodies |
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How do antibodies reduce the threat from pathogens? |
Neutralise toxins by binding to them Prevent entry to host cells Can agglutinate pathogens- clump them together so they are easier for phagocytes to engulf |
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What key groups of people should be immunised? |
People with HIV/AIDS Patients on chemotherapy Pregnant women Health workers |
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Why should people with HIV/AIDS and people on chemotherapy be immunised against disease? |
They have a weakened immune system Their body can't produce many antibodies |
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Why should pregnant women be immunised against disease? |
Foetus has undeveloped immune system |
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Why should health workers be immunised against disease? |
Likely to be at increased risk of disease because they are working close to outbreak |
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Enzymes found in the cytoplasm are described as what kind of protein? |
Intracellular |
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What are the differences between triglycerides and phospholipids? |
Triglycerides have no phophate head, phospholipids have a phosphate head Triglycerides have 3 ester bonds, phospholipids have 2 Triglycerides have 3 fatty acids, phospholipids have 2 |
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What are the similarities between triglycerides and phospholipids? |
Both contain glycerol Both have fatty acid tails Both have ester bonds Both contain the elements C, H and O |
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What should be taken into account when describing the biodiversity of an area? |
Number of habitats/ecosystems Genetic variation within species Total number of species Relative number of individuals within each species |
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What are the aims for the CITES? |
Regulate/control trade in certain endangered species Ensure international trade does not endanger wild populations Prohibit trade in wild plants |
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What are the aims for the Rio Convention on Biological Diversity? |
Sustainable use of organisms Share genetic resources Share access to scientific knowledge Promote ex situ conservation methods |
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What is speciation? |
New species being formed over time
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What is continuous variation? |
Differences between individuals that cover a range of values rather than discrete categories |
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What is adaptation? |
A variation that increases the chance of survival |
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What is an Environment Impact Assessment? |
A study carried out by a local planning authority to judge the effect of a development on the biodiversity of an area |
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What are the characteristics that all member of the animal kingdom share? |
Cells have no cell wall Heterotrophic Eukaryotic Multicellular High degree of mobility |
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Define variation |
The differences between species |
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What are the reasons why the conservation of a species of tree (for example) is important? |
Part of ecosystem, may be a habitat for other animals Part of food chain Wood may be useful for fencing/furniture Potential source of medicine Genetic resource Aesthetic value Resource for scientific research |
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What are the advantages to having a seed bank (as opposed to adult plants)? |
Much smaller- conserve space Last a very long time- won't die after a few years Cheaper to transport Can collect seeds for every plant Most plants produce an excess of seeds Doesn't damage the plant to collect seeds |
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How does fossil evidence support the idea that evolution has taken place? |
Can see how an organism has changed over time Can date the rocks Rocks can show a sequence of changes- general trend from simple organisms to complex |
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What are the specific diseases that contribute to COPD? |
Chronic bronchitis Asthma Emphysema |
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How do organic fertilisers improve the yield of plant crops? |
Manure is decomposed, which adds nutrients to the soil Nitrates are used to make amino acids, which are used to make proteins, which allow the plant to grow |
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What effects does nicotine have on the cardiovascular system? |
Makes platelets sticky and increases the risk of a blood clot or thrombus forming Causes addiction Causes release of adrenaline, which raises heart rate and constricts arterioles This raises blood pressure in arterioles and reduces blood flow to the extremities |
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How can tar cause asthma? |
Settles on lining of the airways and alveoli Increases diffusion distance for O2 and CO2 Reduces ability for gas exchange |
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How can smoking cause lung cancer? |
The carcinogens in tar sit on the lining of the lungs Can get into the nuclei of lung tissue cells Have a direct effect on the DNA of the cell Change the gene for DNA replication Causes uncontrolled replication of DNA Causes a tumour |
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How can smoking cause emphysema? |
Increased mucus production traps more bacteria and viruses This attracts WBCs which release enzymes to get through to the lungs from the blood- break down elastic tissue Due to loss of elasticity, alveoli can't recoil Will eventually burst on exhalation Sequence of events leads to a loss of 1/3 of lung capacity |
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How can smoking cause chronic bronchitis? |
Particles in tar can paralyse and destroy cilia, which means mucus can't be moved up the throat
Stimulates goblet cells to produce more mucus Body attempts to remove mucus by coughing to clear airflow Causes irritation of the airways Causes constant coughing |
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What effects does carbon monoxide have on the cardiovascular system? |
Enters red blood cells and forms carboxyhaemoglobin more readily than oxygen This reduces the oxygen carrying capacity of the blood Can also damage the inner lining of the arteries which causes an increased deposition of cholesterol, leading to artherosclerosis |
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How can smoking lead to artherosclerosis? |
Carbon monoxide damages lining (endothelium) of arteries which causes increased deposition of cholesterol inside the lining, leading to the formation of an artheroma and artherosclerosis. |
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What is taxonomy? |
Study of the principles behind classification Study of differences between species |
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What is a species? |
A group of individual organisms that are very similar in appearance, anatomy, physiology, biochemistry and genetics |
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What is phylogeny? |
The study of the evolutionary relationships between organisms |
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What are fungi? |
A group of organisms in which the body consists of a mycelium- a network of strands called hyphae- and with cell walls made of chitin |
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What kind of nutrition do plants have? |
Autotrophic |
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What kind of nutrition do animals have? |
Heterotrophic |
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What kind of nutrition do protoctists have?
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Autotrophic or heterotrophic |
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What are the 8 taxa of classification? |
Domain Kingdom Phylum Class Order Family Genus Species |
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What is a dichotomous key? |
A series of questions with 2 alternative answers to help you identify a specimen |
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What is the binomial system? |
A way of identifying species by using two names- the genus and the species e.g Homo sapien |
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What are the different ways species are classified? |
Based on differences/similarities in DNA sequences, amino acid sequences, cytochrome C, anatomy, physiological differences, behavioural differences |
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What causes natural selection to occur? |
A selection pressure |
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What is the evidence for evolution? |
Biological molecules are the same in lots of organisms, suggesting that they all originated from the same species Very similar biological molecules in closely related organisms, suggesting they have a recent common ancestor Cytochrome C differences |
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Why is extinction bad? |
Reduces biodiversity, which reduces the gene pool Ethical and aesthetic reasons Reduces the amount of species that could become useful to humans in future |
