Term
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Definition
| Made of different tissues |
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Term
| Why is there a change in max blood pressure, as distance from heart increases? |
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Definition
| Friction of red blood cells against endothelium layer, causing resistance to flow |
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Term
| Why does DNA hybridisation show similarites in organisms? |
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Definition
| Higher temp > More H bonds > More complementary base sequence |
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Term
| Explain how crossing over leads to genetic diversity. (1) |
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Definition
| Results in new combinations of alleles |
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Term
| Why would shorter crops have an advantage over larger ones? |
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Definition
| Less likely to be blown over |
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Term
| Benefits of saving seeds from older plants? |
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Definition
| More genetically varied, so alleles may help future plants survive a change in environment |
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Term
| Why is index diversity better than counting number of species? |
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Definition
| Shows number of species AND number of organisms in each species (1) Some species may be present in small numbers (1) |
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Term
| Explain why structural diversity of plants would cause index diversity of birds to decrease. |
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Definition
| Less habitats available for different species of birds (different birds have different hieghts) (1) Less food sources available (1) |
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Term
| Why can small organisms exchange gases by simple diffusion? |
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Definition
| They have a large SA:Vol, this results in a high rate of diffusion (as rate of diffusion is proportional to SA), plus short diffusion pathway to all cells |
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Term
| Describe oxygen transport in insects, and how water loss is limited (6) |
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Definition
| Air enters through spiracles[1], through internal network of tubes (tracheae) [1] which branches to smaller tubes (trachioles) which are close to all body cells [1], thus decreasing diffusion pathway for gas exchange. There is a diffusion gradient in trachea [1], so oxygen diffuses into cells [1]. To prevent water loss there are waterproof coverings [1], and have valves in spiracles that can be opened/closed [1]. Ventilation by contraction of muscles can maintain conc. gradient [1]. |
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Term
| Name two features that are important to look at when evaluating an experiment. |
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Definition
> Sample size
> Number of species involved
[Just two examples] |
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Term
| What purpose does smooth muscle serve in the arterial wall? |
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Definition
| Allows vasoconstriction, which is contraction of muscles to control direction of blood flow |
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Term
| Why do different species have different numbers of A/T/C/G? |
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Definition
| Different proteins => different genes => different base sequences |
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Term
| What happens to plasmid before horizontal/vertical gene transmission? |
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Definition
| It is replicated [and converted to linear strand for conjugation, only applicable to horizontal g.t.] |
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Term
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Definition
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Term
| When comparing species based on evolutionary history it is important to... |
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Definition
| Discuss how distant common ancestors are, closer on phylogenetic tree => more closely related |
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Term
| What is the purpose of a song in courtship? |
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Definition
| Allows recognition of same species and opposite sex, can be used in dark/underground when other sign stimuli cannot be used. They are unique for each species. |
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Term
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Definition
| Where larger groups are divided into smaller sub-groups, with no overlap |
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Term
| Why does blood pressure decrease along capillary? |
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Definition
| Loss of fluid from capillary results in a decrease in pressure |
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Term
| Where is a logarithmic scale useful? |
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Definition
| When plotting a graph with a large range of values, allowing them to be compared |
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Term
| Why is measuring something 'per gram'/'per cell' useful? |
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Definition
| Allows results to be compared [1], by taking into account mass/number of cells [1] |
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Term
| How should a control group be treated? |
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Definition
| Given saline/placebo instead of drug [1], otherwise treated exactly the same [1] |
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Term
| Why is blood flow slowest in capillary? |
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Definition
| More contact time between RBC and capillary endothelium, so more diffusion of substances can take place |
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Term
| What measurements need to be taken in a potometer? |
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Definition
- Time taken for air bubble to move length of tube
- Diameter of capillary tube to calculate volume |
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Term
| Why does the rate of water uptake in a plant not equal rate of transpiration? |
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Definition
- Some water used by cells (e.g. for turgor/photosynthesis)
- Some water produced by respiration |
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Term
| Why do specific combinations of alleles only occur in a few gametes? |
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Definition
| Relies on crossing over at a specific point, which doesn't happen very often |
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Term
| How could a hospital reduce transmission of MRSA? |
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Definition
Sterilizing equipment between different patients [1]
Isolating patients, to prevent transmission between them [1] |
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Term
| Why is higher than MIC (minimum inhibitory concentration) used when antibiotics are administered? |
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Definition
- Not all antibiotics are absorbed into blood
- Resistant strains may require a higher dose to kill them |
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Term
| Why is a double blind trial reliable? |
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Definition
| Prevents bias and vested interest, also prevents different treatment of volunteer groups by researchers/doctors |
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Term
| Why are hydrogen bonds present in cellulose molecules? |
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Definition
| They connect the parallel strands of cellulose and are strong in large numbers, providing strength and rigidity |
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Term
| If X lives in low pO2 environment, oxygen-haemoglobin curve shifts to left, why? |
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Definition
| Affinity of haemoglobin for oxygen is increased, thus oxygen can still be fully associated with haemoglobin at low pO2 environments |
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Term
| Why does diameter of tree trunk shrink in day? |
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Definition
| This is because the rate of water uptake is increased (as a result of more light and greater temp.) causing a negative pressure in xylem to increase, due to adhesion between water and xylem wall |
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Term
| What does standard deviation overlap suggest in an experiment? |
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Definition
| No real differences in results |
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Term
| Why does the number of organisms in a species decreasing result in a reduced genetic diversity |
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Definition
| There will be fewer organisms, so fewer different alleles [so by definition, reduced genetic diversity] |
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Term
| How would a mutation result in a different protein? |
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Definition
| Change in base sequence of a protein > change in amino acid sequence > change in primary structure > different H bonds form in amino acid sequence > different tertiary structure > different protein |
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Term
| What is the advantage of a short cell cycle? |
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Definition
| The ability to quickly replace cells [NOT REPAIR CELLS, ensure 'quickly' owtte is used] |
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Term
| What is the role of DNA polymerase? |
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Definition
| To join nucleotides in DNA replication [not nitrogenous bases] |
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Term
| What does repeating an experiment result in (in terms of error)? |
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Definition
| A decreased chance of error |
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Term
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Definition
| To prevent water loss when water is not replaced? |
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Term
| How are results from experiment X useful? |
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Definition
Determines whether treatment is:
Cost effective/effective at treating illness/effective dose/effective length of treament/side effects |
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Term
| What would cause a mutation to spread between species? |
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Definition
| Interbreeding/migration/founder effect |
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Term
| How does movement of water in upper branches before lower branches support cohesion-tension theory? |
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Definition
| The water moves first higher up, causing a negative tension and thus pulling more water up the xylem |
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Term
| Why should temperature be kept constant in any investigation? |
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Definition
| Allows comparison of results, as otherwise temp can affect dissolved oxygen/enzyme activity/metabolic rate/etc.. |
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