1510398
| Pregunta | Respuesta |
| Where does cell respiration take place? | Mitochondria |
| Where and why are the numbers of mitochondria highest? | Liver and muscle cells - need larger amounts of energy to carry out their functions |
| What are chromosomes? | Long coiled molecules of DNA divided up into regions called genes. |
| Describe the structure of DNA | 2 strands coiled to a double helix, which has cross links made of chemicals called 'bases'. 4 different bases in DNA, each cross link has 2 bases, known as base pairs. |
| What did Watson and Crick originally think about the structure of DNA? | DNA was a triple helix, not a double helix. |
| What did Rosalind Franklin and Maurice Wilkins discover? | Used X-Ray crystallography to take pictures of DNA. Pictures showed DNA in a double helix. |
| What did Erwin Chargaff discover? | That there are equal numbers of A and T bases and G and C bases in DNA! |
| What do chemicals called bases do? | Hold strands of DNA molecules together by forming cross links. |
| What are Ribosomes? | Found in the cytoplasm - used in the cell when proteins are made. |
| What is a genetic code? | Made up be genes in the body. Controls cell activities. Controls characteristics e.g. hair colour. |
| What would happen to your body without DNA? | DNA - code for making proteins. Without it, can't make proteins for growth and cell repair. |
| An example of DNA controlling a function | Codes for enzymes involved in respiration, otherwise respiration wouldn't be able to happen. |
| How is a duplicate copy of DNA made? | 1. Bond between 2 strands breaks 2. Strand unwinds 3. New bases join old strands to make new strands. |
| How are amino acids made? | Each amino acids has its own code of 3 bases. Every time the same base occurs three times, an amino acid is added to make the protein. |
| Where/how are proteins made? | Proteins are made in the cytoplasm of a cell, not nucleus. Genes can't leave the nucleus, so a copy of the gene is needed. This copy can leave the nucleus to go into the cytoplasm so that proteins can be made by the cell. |
| Describe protein synthesis | 1. Transcription - DNA code copied 2. Copied code called mRNA 3. mRNA leaves nucleus & travels to ribosomes. 4. Translation - At ribosomes - code used to put amino acids together in right order to form protein |
| What is collagen? | Protein, found in walls of arteries to make walls stronger. |
| What is insulin? | Hormone used to control blood glucose levels. |
| What is haemoglobin? | Used to carry oxygen around body. |
| What is mutation? | A gene code changes. Cause shape of protein to change so it can't do it's job in a cell. |
| What are enzymes? | Proteins - control body activities like digestion. |
| What can gene mutation be caused by? | - Spontaneously - Radiation - Chemicals (tar in cigarettes) |
| What is haemophilia? | Protein needed to clot blood isn't made by mutated cell. Person bleeds and this can be fatal as they can bleed to death. |
| How can mutations be beneficial? | E.g. sickle cells anaemia mutation means people that have it are less likely to die from malaria. Some mutations don't have any effects. |
| What is a primary structure? | - Each protein has own number and sequence of amino acids. - Determined by sequences of bases. - PS folds into different shapes - each protein molecule has different shape to carry out function |
| What can happen to amino acids in mutation? | Mutation - sequences of bases in DNA change - amino acid sequence changes - different shaped protein that can't do its job. |
| What are enzymes? | Molecules that speed up chemical reactions - work best at particular temps. |
| How does 'lock and key' work? | -Each enzyme = unique sequence of amino acids. -Each enzyme has different shape -In the shape = a structure called active site -Only 1 type of substrate fits into active sit Once substrate attached to active site, it becomes a product. -Only 1 key opens lock - 1 enzyme can change PARTICULAR substrate. |
| What happens when an enzyme denatures? | If the shape changes, it can't catalyse reactions anymore. It's an irreversible reaction - enzyme no longer functions. Substrate can't fit into active site. |
| What happens to enzymes at high temperatures? | - Temp increases - Molecules gain energy - More collisions - ROR increases - Above optimum = denaturing |
| What is temperature coefficient? | Q.10 = effect of temp on ROR calculated using: rate at higher temp/rate at lower temp |
| What is aerobic respiration? | Uses oxygen to release energy: glucose + oxygen --> carbon dioxide+water |
| Balanced symbol equation for respiration? | C6H12O6 + 6CO2 → 6CO2 + 6H20 + ENERGY |
| What is RQ? | Respiratory Quotient - finding out respiration rate = CO2 produced/O used *Anaerobic respiration that uses glucose, RQ is always 1 |
| What is ATP? | Respiration releases energy that's stored in ATP. It's a molecule used as energy source for processes inside cell. |
| What's metabolic rate? | Amount of energy body needs. Can be measured by measuring oxygen rate because more oxygen = faster respiration = more energy used |
| Why does pulse rate increase during exercise? | To get rid of waste CO2 produced by cells as it's breathed out. |
| What's anaerobic respiration? | Releases energy WITHOUT oxygen and produced lactic acid as waste: Glucose → lactic acid |
| What does lactic acid do to your body? | Collects in muscles - stops them working temporarily - muscle fatigue - cramps - hurts |
| What causes anaerobic respiration? | Muscle cells don't get oxygen quick enough 2 release energy - resort to anerobic |
| Why is energy released in anerobic less that=n aerobic respiration? | Glucose's only partly broken down - lactic acid builds up - more O to remove it - heart faster so blood can carry LA away from muscles - 2 break down in liver - heavy breathing to obtain more O - O debt is extra O for removing LA - panting ALSO replaces O to let aerobic respiration happen |
| When do cells divide? | When body needs to: 1- grow 2- replace worn out cells 3- repair damaged tissue |
| What is AMOEBA? | Unicellular organism - 1 cell body Reproducing - divides to form 2 cells - asexual reproduction |
| Multicellular organism advantages? | 1 - Can grow large 2- Cell differentiation - cells different shapes 2 carry out specialised jobs 3- More complex - develop different organ systems - work together to make organism |
| How are sperm adapted to travelling a long way? | - Has large amount of mitochondria to release energy for motion - Has acrosome structure on head that releases enzymes to digest egg cell membrane |
| What are platelets? | Help to clot blood when you get a cut |
| How is red blood cell adapted? | - Red color from haemoglobin when it combines with it - H lets it be transported around body. - No nucleus - more space for oxygen - Disc shaped with dents on both sides- absorb lots of oxygen - Small - carry oxygen to all body parts. |
| What do capillaries do? | Join arteries to veins and carry blood through tissue. Oxygen's exchanged b/w capilarries and body tissue |
| Stem cells | - After fertilizing, egg contains undifferentiated cells called STEM CELLS - Have simple cell structures - Then divide to form specialised cells - Can be taken to treat medical conditions - People are against is coz it involves human embryos |
| Why are embryonic stem cells better than adult stem cells? | Have the ability to specialise into most body cells whereas adult cells only differentiate into few types of cells. |
| Meristems? | Special area where cell division in plants take place. Found at tips of shoots and roots |
| Problems with interbreeding? | = Reduction in gene pool - Less variation with smaller gene pool = E.g. loose gene pool that helps animal survive a disease = more chance of an harmful recessive gene being expressed. |
| Plant, animal and bacterial cells? | Plant - cell wall, chloroplast, vacuole, DNA inside nucleus animal - vacuole (no cell sap) bacterial - no mitochondria or chloroplast, floating circular strands of DNA |
| What is dry and wet mass? | Wet - mass of whole organism measured while alive Dry - mass of organism after all water's been removed (dead) |
| Why is dry mass better than wet mass? | Water content can change depending on weather conditions e.g. less water when hot. However, organism MUST be dead even tho it's more accurate. |
| Why does a foetus's head grow faster than other parts of it's body? | So brain's developed quickly so it can coordinate complex human structure and human activity. |
| Arguments FOR and AGAINST stem cells? | FOR = good to use embryos to cure disease from leftover IVF treatment which would otherwise be destroyed AGAINST = Wrong to experiment on embryos - life's sacred - shouldn't 'play God' - wrong, unnatural |
| Why might a farmer use selective breeding on cows? | 1. Choose cows that produce high volume of milk/high milk yield 2. Choosing cows to produce more rich/creamy milk 3. Breed cows for hardiness/early maturity and high no. of offspring. |
| What is GM? | Transferring of genes. |
| Advantages of GM? | 1. IMPROVE CROP RESISTANCE - to frost damage, disease, herbicides 2. VITAMIN A - rice diet lacks vit A - genes that make beta-carotene transferred from carrots to rice plants so ppl can get it. 3. INSULIN - gene that makes insulin - inserted in bacteria - make insulin on large scale - treat diabetes |
| How is DNA modified by GM? | 1. Select the characteristic 2. Identify & isolate gene 3. Insert gene into chromosome of different organism 4. Organism replicates w/gene w/new protein |
| Ethical advantages of GM? | 1. Producing disease resistant crops - feed more population 2. Growing crops - survive in dry soil - feed everyone 3. Replacing faulty genes - reduce disease |
| Ethical disadvantages of GM? | 1. GM food-not safe-long term 2. unborn babies-aborted-genetic faults 3. GM plants can crossbreed w/wild plants & release new genes into environment 4. Insurance companies - genetically screen - refuse ppl tht have increased chance of ilness 5. Designer babies |
| What is gene therapy? | - Changing person's gene to cure genetic disorder - Can involve gametes (sex cells) - Those that involve gametes are bad as it can affect future generations as genes are passed down w/o letting them have a say in it especially if it leads to problems |
| What is cloning? | - Make copies of plants/animals - Genetically identical - Same DNA as original |
| What is asexual reproduction? | - Producing identical copies - E.g. plants and Amoebe, spider plants, strawberries, potatoes |
| Advantages of commercial cloning? | - Cloned plants will be genetically identical to parents so characteristics will be known - It's possible to mass-produce plants that could be hard to grow from seeds :) |
| Disadvantages of commercial cloning? | - ANY susceptibility to disease will affect all plants - Reduction in GENETIC VARIATION reduces potential for more selective breedin |
| How can cloned plants be produced? | 1. Pick parent plant w/desired characteristics 2. Scrape off small tissue pieces into beaker containing nutrients & hormones and NO bacteria 3. Genetically identical plants grow *Cloning plants easier than animals coz plants able 2 differentiate/specialise but animal cells lose this ability* |
| Who was Dolly? | - Animal cloned artificially - Produced by nuclear transfer - Scientists placed nucleus of udder cell from sheep into empty egg cell w/no nucleus - Short electric current made cell divide - Then implanted into surrogate mother sheep to grow |
| Uses of cloning? | 1. It's possible to clone human embryos like animals - can be used to provide stem cells for medical 2. Mass production of animals w/desirable characteristics 3. Producing animals that've been genetically engineered to provide human products. |
| Ethical issues of cloning? | - Unreliable - lots of cloned embroys don't survive - Cloned animals have limited life span - die early - Effect of cloning on human's mental/emotional development - unknown - Religious - cloning is wrong - Using embryos/tampering them is controversial |
| Benefits of cloning? | - Genetically identical - same characteristics - Sec and timing of birth of animal controlled - Top-quality cows can be kept for egg/sperm donation while other animals used to give birth to the young |
| Risks of cloning? | - Cloning reduces genetic variation - All genetical copies - genetically same - one disease can kill them all - Might not be as healthy or life span as usual animals. |
| Animal organ donors? | - Shortage of human organ donors - Genetically engineer - animal - organ isn't rejected by human - animal cloned - no more waiting list - infections can pass from animal to human - animal welfare and rights |
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