Biology Flashcards: Common Questions and Answers

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  • Created by: Alice
  • Created on: 26-05-14 21:02
Name the two components that make up the DNA backbone.
Deoxyribose and Phosphate
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Explain how a DNA mutation can result in a non-functioning enzyme.
Change in triplet code changes amino acid sequence, change in ionic/disulphide/hydrogen bonds, change in tertiary structure and active site, substrate not complementary, no ES complexes made
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Why does the transpiration rate not equal the water uptake rate in a plant?
Water used for photosynthesis, respiration, and mechanical support
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If wind level is low and the stomata are not in pits, why is there a reduction in water loss from plant leaves?
Water vapour accumulates outside of the stomata - increases humidity - reduces the water potential gradient
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Suggest two ways of reducing the transmission of bacteria MRSA
Isolate patients (quarantine), sterilisation of wards and equipment, screening of doctors and patients
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If a person is treated with antibiotics often, the bacteria can become a "resistant strain". Explain how.
Mutation occurs, resistant gene develops, survives and reproduces and spreads resistance by horizontal transmission (conjugation) and vertical transmission
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How does haemoglobin in red blood cells load and unload oxygen in the body?
Loading of O2 in lungs - high O2 partial pressure so Haem becomes saturated. Unloading at low O2 partial pressure - in respiring tissues. Unloading at high CO2 conc, low pH, high temp
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Compare the structural features of veins and arteries.
Valves - Arteries NO, Veins YES. Wall thickness - Arteries THICK, Veins THIN. Elastic and muscle tissue - Arteries MORE, Veins LESS. Lumens - Arteries NARROW, Veins WIDE.
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Explain how smooth muscle in the arterioles can reduce blood flow.
Muscle contracts and causes vasoconstriction where the lumen is narrowed.
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Explain how elastic tissue in the arteries evens out blood flow.
Stretches at high pressure, recoils at lower pressure.
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Explain how veins are adapted to ensure blood returns to the heart.
Veins run close to muscles which contract and increase pressure inside the vein so blood is pushed back to the heart. Semi lunar valves prevent backflow. Blood drawn to area of low pressure created by thorax when breathing.
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What causes the decrease in blood pressure in the capillaries?
Loss of fluid, friction on capillary wall.
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How does tissue fluid return to the circulatory system?
Large plasma proteins reduce WP in capillary, creates a water potential gradient so fluid flows into capillary to dilute it by osmosis, lymph vessels drain tissue fluid
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How are fish gills adapted for efficient gas exchange?
Many lamellae and gill filaments so large surface area so fast diffusion rate. Thin epithelium on lamellae so short diff path. Counter current flow maintains concentration gradient, water always next to blood with lower O2 conc.
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Describe how an insect is able to obtain oxygen and limit water loss.
Air/O2 enters spiracles, travels through trachea networks and tracheoles by diffusion, tracheoles lead to cells/oxygen diffuses in. Ventilation replenishes air in trachea, body covered in waterproof waxy cuticle, spiracles close when body inactive.
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Describe how single celled organisms exchange respiratory gases and explain why this method of gas exchange is only possible in very small organisms.
Diffusion through cell membrane (partially permeable), small organisms have large SA: VOL ratio, short diffusion pathway
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What is meant by genetic diversity?
Difference in alleles/genes/base sequence
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What is meant by a hierarchy?
Groups within larger groups, no overlapping
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What is meant by a phylogenetic relationship?
Shows evolutionary relationship
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Why is it that comparing the base sequence of a gene gives more information than comparing genes' amino acid sequence?
Base sequence shows introns, triplet code is degenerate so the same amino acid can be coded for by different base sequences.
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Describe the processes which lead to a reduced genetic diversity in populations of organisms.
Reduced GD - reduced allele variety - reduced gene pool. Founder effect - isolated individuals found new pop with fewer allelles. Genetic bottlenecks - fall in pop, fewer alleles from survivors. Selective breeding - undesirable alleles die out
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Give two reasons courtship behaviour improves the probability of successful mating
Indicates fertility, attracts members of same species.
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What is a species?
Organisms with similar characteristics who can interbreed to create fertile offspring
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Explain why it is more useful to calculate the index of diversity rather than record the number of each species present.
Measures number of species and number of individuals present in species. Some species may only be present in small numbers.
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What information is needed to calculate the index of diversity for each species?
Number of each species
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Explain the effect of monoculture on: plant species diversity
Reduced - only one crop grown. Other species are removed by weeding out, herbicides. Main crop is the main/better competitor for light and nutrients than others.
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Explain the effect of monoculture on: animal species diversity
Reduced due to fewer food sources, fewer habitats and ecological niches, use of pesticides reduces species diversity
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Why take repeat measures in an experiment?
Identify anomalous results, create a reliable mean, make the test more reliable
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How does a double blind trial improve reliability?
No bias, no placebo effect, no vested interest of scientists
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How can a scatter graph be used to identify trends in results beyond the last plotted point?
Use a line of best fit and extrapolate beyond the last result
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How do you ensure a sample gives reliable data?
Large sample size, choose randomly
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Why is standard deviation more useful than the range?
Shows variation around the mean, not affected by anomalous results
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How should a control group be treated?
Treated the same but with a placebo
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Why is better to measure in per gram of body mass/percentage/ratio?
Allows comparison between organisms of different masses
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Describe how comparisons of biological molecules in two species can be used to find out how closely related they are.
Compare base sequence - DNA Hybridisation - Heat, separate DNA strands, break bonds - Mix strands with other species' DNA strands, allow to cool for new bonds to form - Heat to separate, higher temperature = closer related
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Describe how comparisons of biological molecules in two species can be used to find out how closely related they are.
Compare protein found in both species - compare amino acid sequence -
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Describe how comparisons of biological molecules in two species can be used to find out how closely related they are.
Immunological evidence - inject serum containing proteins of species A into animal - obtain serum containing antigens from species A - add serum containing proteins of species B to antibodies - more precipitate formed = closer related
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Other cards in this set

Card 2

Front

Explain how a DNA mutation can result in a non-functioning enzyme.

Back

Change in triplet code changes amino acid sequence, change in ionic/disulphide/hydrogen bonds, change in tertiary structure and active site, substrate not complementary, no ES complexes made

Card 3

Front

Why does the transpiration rate not equal the water uptake rate in a plant?

Back

Preview of the front of card 3

Card 4

Front

If wind level is low and the stomata are not in pits, why is there a reduction in water loss from plant leaves?

Back

Preview of the front of card 4

Card 5

Front

Suggest two ways of reducing the transmission of bacteria MRSA

Back

Preview of the front of card 5
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