Biology A level Paper Two revision exam and answers, Exams of Biology

Download Biology A level Paper Two revision exam and answers and more Exams Biology in PDF only on Docsity! Biology A level Paper Two revision exam and answers 1. What is homeostasis? - Correct Answer the maintenance of a relatively stable internal environment or within restricted limits 2. List three conditions in the body that have to be controlled. - Correct Answer three from: core body temperature, blood plasma, pH, plasma water potential, blood glucose concentration 3. Why must pH be controlled? - Correct Answer to maintain protein / enzyme activity 4. Why must temperature be controlled? - Correct Answer to maintain protein / enzyme activity 5. What is a negative feedback loop? - Correct Answer a change from the normal will cause the body to correct that change to bring it back to the set value 6. What is glycogenolysis? - Correct Answer breakdown of glycogen to glucose 7. What is gluconeogenesis? - Correct Answer producing glucose from non - carbohydrate sources 8. What is glycogenesis? - Correct Answer production of glycogen from glucose 9. What are the names of the two hormones involved in controlling blood glucose concentration? - Correct Answer insulin and glucagon 10.Which organ detects blood glucose concentration and secretes insulin and glucagon? - Correct Answer pancreas 11.Which cells in the pancreas make and secrete insulin? - Correct Answer beta (B) cells 12.What is the role of CAMP in the second messenger model? - Correct Answer it activates protein kinase to convert glycogen to glucose 13.Which type of diabetes is insulin dependent? - Correct Answer type I 14.Write a definition for diabetes. - Correct Answer a medical condition where the patient is unable to control their blood glucose concentration 15.What is osmoregulation? - Correct Answer the balancing and control of water potential of the blood 16.Which organs are responsible for osmoregulation? - Correct Answer kidneys, brain 17.Which part of the brain is responsible for monitoring water potential in blood plasma? - Correct Answer hypothalamus 18.Which part of the brain synthesises ADH? - Correct Answer hypothalamus 19.Which part of the brain stores and secretes ADH? - Correct Answer posterior pituitary gland 20.What does ADH stand for? - Correct Answer antidiuretic hormone 21.What is the role of ADH? - Correct Answer to conserve water in the body 22.How does insulin reduce blood glucose concentration? - Correct Answer increases rate of respiration, increases uptake of glucose in target cells by increasing the number of glucose channel proteins in the cell surface membrane, increases the conversion of glucose to glycogen and fats 23.How does glucagon raise blood glucose concentration? - Correct Answer activates enzymes in target cells to increase conversion of glucagon to glucose, and gluconeogenesis 24.Why the action of adrenaline is called the second messenger model? - Correct Answer adrenaline cannot enter the cell; it is the first messenger and activates a second messenger in the target cell 25.When is adenylate cyclase activated in the second messenger model? - Correct Answer when adrenaline forms a hormone - receptor complex with specific receptors on target cell surface membranes 26.What is the role of respiration? - Correct Answer to provide energy in the form of ATP to living cells 27.Why can glycolysis take place in both aerobic respiration and anaerobic respiration? - Correct Answer it does not require oxygen 28.Where does glycolysis take place in a cell? - Correct Answer in the cytoplasm (cytosol) 29.How many molecules of ATP are used during glycolysis? - Correct Answer two 58.What is the sequence of events involved in transmitting an impulse at a synapse? - Correct Answer 1 presynaptic neurone has an action potential at its surface membrane 59.2 this action potential causes neurotransmitter molecules to be released into synaptic cleft 60.3 neurotransmitter molecules bond temporarily with receptors on postsynaptic neurone membrane 4 molecules cause depolarization of postsynaptic neurone; if this is above the threshold, impulse will be sent 61. In a cholinergic synapse, what happens to acetylcholine when it is released from the synaptic knob and what is the impact of this? - Correct Answer diffuses across the cleft and binds to receptors on the postsynaptic membrane, delaying the impulse by about 0.5 MS 62. In a cholinergic synapse, what determines whether the impulse is triggered in the postsynaptic neurone? - Correct Answer it has to reach the threshold potential 63.What happens to acetylcholine after it has bound to its receptor? - Correct Answer acetylcholinesterase on postsynaptic membrane hydrolyses Ache; breakdown product choline is reabsorbed into synaptic knob 64.What two sources of carbon dioxide do plants use? - Correct Answer aquatic and atmospheric 65.Why energy are transfers never 100 % efficient? - Correct Answer energy is transferred to surroundings as heat (via respiration) 66. In which two ways can biomass be measured? - Correct Answer mass of carbon or dry mass of tissue per given area 67.What can calorimetry be used to measure? - Correct Answer the amount of chemical energy stored in dry biomass 68.What is the definition of gross primary production (GPP)? - Correct Answer the chemical energy store in plant biomass, in a given area or volume 69.What is the definition of net primary production (NPP)? - Correct Answer the chemical energy store in plant biomass after respiratory losses to the environment have been taken into account 70.What is the equation used to calculate net primary productivity? - Correct Answer NPP = GPP - R 71.GPP - gross production 72.R - The respiratory losses to the environment 73.How is net production of consumers (N) calculated? - Correct Answer N = I - (F + R) 74. I - chemical energy store in ingested food 75.F - Chemical energy transferred to the environment through faeces and urine 76.R - Respiratory energy transferred to the environment 77.What is the unit for GPP, NPP, and N? - Correct Answer biomass in a given area and time (kJha^-1 year^-1)) 78.Which farming practices can increase efficiency in food chains? - Correct Answer farming animals: reduce respiratory losses by reducing movement and heating enclosures 79.Farming plants: simplify food webs by removing weeds and using pesticides 80.What are three examples of biological molecules that contain nitrogen? - Correct Answer amino acids, proteins, nucleic acids 81.Which forms of inorganic molecules and ions, containing nitrogen, are found in biological systems and the physical environment? - Correct Answer atmospheric nitrogen gas ( N₂ ) , ammonium ions ( NH4+) , nitrates ( NO3 ) , and nitrites ( NO₂ ) 82.What are the main processes that recycle nitrogen in the environment? - Correct Answer feeding, digestion, excretion, death, decomposition nitrogen fixation (by bacteria plants and lightning) 83.Which are the microbial processes of recycling nitrogen in the environment? - Correct Answer nitrogen fixation, nitrification, denitrification, and ammonification 84.Define the term species. - Correct Answer a group of organisms with similar characteristics, that are reproductively separated from other species and can breed together to produce fertile offspring 85.Define the term gene pool. - Correct Answer the set of all the alleles of each of the genes of a particular species within a population 86.What does the Hardy - Weinberg principle predict? - Correct Answer that allele frequencies will not change from generation to generation without external influence 87.What does the Hardy - Weinberg equation calculate? - Correct Answer the frequency of alleles, genotypes, and phenotypes in a population 88.What are three causes of genetic variation? - Correct Answer 1 mutation 89.2 meiosis (independent assortment and crossing over) 90.3 random fertilization of gametes 91.What three factors can prevent an organism from reproducing? - Correct Answer predation, disease, competition for resources - food, water, space, mates 92.Define evolution. - Correct Answer the change of gene frequency within a population 93.What is meant by a selective advantage? - Correct Answer organisms with variations that allow them to survive are more likely to reproduce 94.What two steps can allow a new species to evolve from an existing species? - Correct Answer if two populations are reproductively separated, differences in their gene pools can accumulate; if these differences make it impossible for the two populations to breed and produce fertile offspring, then they become two species 95.What is allopatric speciation? - Correct Answer species formation due to separation by geographical barriers 96.What is genetic drift? - Correct Answer the random change of allele frequency due to only some of each generation reproducing 97.What are quadrats used for? - Correct Answer sampling and estimating a population of organisms that have low motility or are sessile 98. In which two ways can quadrats be used? - Correct Answer random sampling of an area or as a belt transect 99.What is the mark - release - recapture technique used for? - Correct Answer estimating populations of motile organisms 100. What is primary succession? - Correct Answer when species start to colonies a bare piece of land (e.g., rocks); this changes the environment so that new species can colonies, until there is a climax community 101. What is a climax community? - Correct Answer the stable community at the end of a period of succession 102. State two examples of where there is conflict between humans and the environment. - Correct Answer using wood as a resource, fishing 103. What is the purpose of conservation? - Correct Answer managing succession to maintain habitats and biodiversity 132. How are somatic (body) cells turned back into stem cells? - Correct Answer they are reprogrammed using transcription factors 133. What are the two main factors that influence cancer development? - Correct Answer environment and genes 134. What is the role of tumor suppressing genes in normal cell division? - Correct Answer inhibit cell division 135. Why cell division is normally tightly regulated? - Correct Answer to prevent uncontrolled cell division and the formation of tumors 136. Proto - oncogenes mutate into which type of gene? - Correct Answer oncogenes 137. Which type of cancer has been associated with increased levels of oestrogen? - Correct Answer breast cancer 138. What do the terms benign and malignant mean when referring to tumors? - Correct Answer benign - usually non - life threatening and tend not to spread 139. Malignant - usually harmful and can spread to other parts of the body 140. How do methylation and acetylation affect transcription? - Correct Answer methylation makes DNA inaccessible to transcription factors 141. Acetylation increases transcription 142. What are the two groups of reactions of photosynthesis called? - Correct Answer light - dependent reactions and light - independent reactions 143. What happens to chlorophyll when it absorbs light? - Correct Answer it becomes photoionised and the energy of electrons is increased, producing ATP and reduced NADP 144. Where is chlorophyll found? - Correct Answer on the internal membranes of chloroplasts 145. Write a definition for chemiosmosis. - Correct Answer the diffusion of hydrogen ions (protons) through a partially permeable membrane, which is linked to the generation of ATP 146. How is carbon dioxide taken into the cell biochemistry? - Correct Answer it reacts with ribulose bisphosphate (RuBP) (a simple sugar); this is catalyzed by the enzyme rubisco 147. What is the role of the Calvin cycle in photosynthesis? - Correct Answer to fix carbon dioxide and make it into useful organic compounds (simple sugars) 148. What are the sources of energy for the Calvin cycle? - Correct Answer ATP and reduced NADP from the light - dependent reactions 149. What is the product of carbon dioxide reacting with RuBP? - Correct Answer two molecules of glycerate 3 - phosphate (GP) 150. What is triose phosphate used for? - Correct Answer regeneration of RuBP and making useful organic molecules within the plant 151. What are the types of useful organic compounds produced by photosynthesis? - Correct Answer glucose, cellulose, starch, disaccharides, lipids, and amino acids 152. What happens to water during photosynthesis? - Correct Answer photolysis: during the light - dependent reactions s, it is split to produce oxygen, two electrons, and two protons to reduce NADP 153. What is the balanced symbol equation for photosynthesis? - Correct Answer 6CO₂ + 6H₂O → C₂6H12O6 + 60₂ 154. What is the likely limiting factor in a greenhouse, heated with a paraffin heater and sufficient watering? - Correct Answer light intensity 155. How can chlorophylls be separated experimentally? - Correct Answer thin layer or paper chromatography 156. What is the role of the dehydrogenase enzyme? - Correct Answer catalyses the reaction where electrons are accepted by NADP in chloroplasts 157. In the Calvin cycle, what is glycerate 3 - phosphate (GP) reduced to? - Correct Answer triose phosphate 158. In which reactions of photosynthesis is carbon dioxide taken in? - Correct Answer light - independent 159. Decreased acetylation - Correct Answer when acetyl groups removed, increases positive charge of histones, DNA will condense due to more attraction, wrapping tightly around histones. 160. Increased methylation - Correct Answer blocks binding site so TF cannot bind can attract proteins which deacetylation, histones in ONA are more tightly bound, so TF can't bind. 161. RNA interference: not actively involved in gene expression Si RNA: - Correct Answer Enzyme cuts double stranded RNA into small sections. 162. Double strands become single stranded. (SiRNA) 163. One strand combines with enzyme 164. SiRNA guides enzyme to mRNA and binds by complementary base pairs 165. Enzyme cuts mRNA into pieces... can't be translated 166. miRNA - Correct Answer similar to SiRNA , but less specific associates with a protein instead of enzyme and when it is formed , it is folded , processed into a double strand and then single stranded fragments . MiRNA blocks translation. MiRNA kis broken down elsewhere or stored. If stored mRNA can be translated at another time. 167. Transcription factors - - Correct Answer Activator - allows RNA polymerase to bind. 168. Represser - blocks RNA polymerase from binding. 169. Promoter region - Correct Answer area where RNA polymerase binds. 170. Oestrogen. - Correct Answer -increase leads to breast cancer 171. Switches genes on by binding to receptor site on transcription factor. This activates. DNA binding site. 172. Tumor suppressor genes - Correct Answer TSG -normally slow down cell cycle 173. Mutation = loss of function less protein produced. 174. Therefore, rapid cell division with cell mutations... (Lots of cells, w / structural / functional differences) 175. BRAC 1 176. BRAC 2 177. TPS3 - PS3 codes 178. Too much methylation 179. Tumor suppressor genes - Correct Answer Repair mistakes in DNA triggers apoptosis 180. The second messenger model - Correct Answer 1 Adrenaline, the first messenger, binds to specific receptors on target cell surface membranes to form a hormone - receptor complex. 181. 2. The hormone receptor complex activates an enzyme, adenylate cyclase, inside the membrane. 182. 3. The activated adenylate cyclase converts ATP into cyclic AMP. 183. 4. Camp acts as the second messenger and activates another enzyme in the cytoplasm, kinase, causing the conversion of glycogen to glucose.