all2 Flashcards
how the student could have used his slide to find the number of stomata per cm2
- by using a method of determining area of field of view/area seen using microscope
- by counting the number of stomata in field of view
- and using repeats and calculating a mean
The stomata on the leaves of pine trees are found in pits below the leaf surface. Explain how this helps to reduce water loss
- water vapour accumulates / increased humidity/ reduced air movement around stomata
- so water potential/diffusion gradient is reduced
How blood plasma is different from tissue fluid
-more/larger proteins / less urea/carbon dioxide / more glucose/amino acids/fatty acids/oxygen/ high(hydrostatic) pressure
The blood pressure is high at the start of the capillary. Explain how the left ventricle causes the blood to be at high pressure.
-contracts
The blood pressure decreases along the length of the capillary. What causes this decrease in pressure?
- loss of fluid/volume
- so friction/resistance of capillary wall
Explain the link between a low concentration of protein in blood plasma and the accumulation of tissue fluid
- Water potential (in capillary) is higher/less negative so the water potential gradient is reduced
- therefore more tissue fluid formed at arteriole end
- and less/no water is absorbed into blood capillary
- by osmosis into blood capillary
Why it may be more useful to calculate the index of diversity than to record only the number of species present
- measures number of individuals of each species and number of species
- some species only present in small numbers
Gas exchange in fish takes place in gills. Explain how two features of gills allow efficient gas exchange
- filaments/lamellae provide large surface area
- thin/flattened epithelium are only one/two cell layers so there is a short diffusion pathway between water and blood
- countercurrent/blood flow maintains concentration/diffusion gradient
The scale for plotting body mass is a logarithmic scale. Explain why a logarithmic scale was used to plot body mass.
-so that a large range of values can fit on a graph
Describe the relationship between body mass and oxygen uptake
-Decrease in uptake with increase in mass / negative correlation
The zoologist measured oxygen uptake per gram of body mass. Explain why he measured oxygen uptake per gram of body mass
- enables comparison
- as animals differ in size/mass
Heat from respiration helps mammals to maintain a constant body temperature. Use this information to explain the relationship between body mass and oxygen uptake shown in the graph.
- smaller animals have larger surface area to volume ratio
- so lose more heat per gram of tissue
- and respire more/faster relative to body mass
- and oxygen is used in respiration
how the scientists should have treated the control group
- given only saline
- otherwise treated exactly the same way
factors which should be considered when deciding the number of mice to be used in this investigation
- ethical consideration, e.g., leads to death/suffering of mice
- large number to improve reliability / reduce sampling error
- number of mice related to cost/space available/animal husbandry
What information does standard deviation give about the volume of the tumours in this investigation?
-the degree of spread/variation from the mean
ways in which courtship behaviour increases the probability of successful mating
- recognition of same species
- stimulates release of gametes
- recognition of mate/opposite gender
- indication of sexual maturity/fertility
A female with a head length of 50 mm selected a mate. Explain how you could use the graph to predict the total head length of the mate selected.
- use line of best fit
- and extrapolate/extend line as required
How comparisons of biological molecules in these two species could be used to find out if they are closely related.
- compare DNA
- sequence of bases/nucleotides
- DNA hybridisation
- separate DNA strands / break hydrogen bonds
- mix DNA/strands of different species –the temperature/heat required to separate hybrid strands indicates relationship
- compare same/named protein
- sequence of amino acids /primary structure
- immunological evidence – not a mark
- inject seahorse protein/serum into animal
- obtain antibodies/serum
- add protein/serum/plasma from other seahorse species
- the amount of precipitate indicates relationship
How downward movement of the diaphragm leads to air entering the lungs.
- increases volume in lungs/thorax
- lowers pressure in lungs/thorax
- air is pushed in by higher outside pressure, down a pressure gradient
Pulmonary ventilation equation
Pulmonary ventilation= tidal volume x ventilation rate
Mitochondrion function
-aerobic respiration
Why certain structures can’t be seen using an optical (light) microscope
- resolution is not high enough
- the wavelength of light is too long
Sucrose monosaccharaides
- glucose
- fructose
Lactose monosaccharaides
- glucose
- galactose
Osmosis/water potential- diarrhoea (cholera bacteria increases chloride ions into lumen)
- water moves into the gut
- so there is a lower water potential of gut lumen
- this means water moves down a water potential gradient by osmosis
- so not enough water is reabsorbed
Non-competitive inhibitors- now imatinib stops uncontrolled cell division in leukaemia
- imatinb is a non competitive inhibitor as it binds to a site other than the active site (allosteric site)
- this means that the active site is now the wrong shape and no e-s complex is formed
- so the uncontrolled cell division is now controlled
blood vessel to which the artificial heart is connected
Aorta
why the left ventricle requires the help of the artificial heart but the right ventricle does not
- because the left ventricle pumps the blood further (to the whole body except lungs)
- meaning It does most the work and produces a greater force/pressure
why the pulse recordings in the doctor’s surgery were taken when the men were lying down
-the patients were at rest in controlled conditions using a standard position
why the pulse felt can be used to measure heart rate
- because it is caused by pressure, a surge of blood
- from one contraction of the left ventricle of the heart
Why people with AIDS die because they are unable to produce an immune response to pathogens
- because people are infected by other pathogens
- which reproduce and cause disease
- which can damage cells
- and release toxins
- and the immune system can’t prevent or stop the events
why because HIV shows a lot of antigenic variability a vaccine might not be effective against HIV
-antigen on HIV changes
-so specific receptor no longer binds to new antigen
OR
-there are many different stands of HIV
-and it is not possible to make a vaccine for all antigens
Ways in which substances can cross the cell surface membrane
By osmosis - From a high water potential to a low water potential/down a water potential gradient - Through aquaporins/water channels By facilitated diffusion - Channel/carrier protein - Down concentration gradient By active transport - Carrier protein/protein pumps - Against concentration gradient - Using ATP/energy (from respiration); By phagocytosis/endocytosis - Engulfing by cell surface membrane to form vesicle/vacuole By exocytosis/role of Golgi vesicles - Fusion of vesicle with cell surface membrane
How atheroma formation increases a person’s risk of dying
- atheroma is fatty material
- in the wall of an artery
- which causes higher risk of aneurysm
- and a higher risk of thrombus formation/blood clot
- which could block the coronary artery
- so less oxygen/glucose goes to the heart muscle
- and reduces respiration
- causing a heart attack (myocardial infarction)
- or it could block an artery to the brain
- causing a stroke
type of reaction that would break down these carbohydrates into their monomers.
Hydrolysis
Give a feature of starch and explain how this feature enables it to act as a storage substance
- Coiled / helical / spiral
- (So) compact / tightly packed / can fit (lots) into a small space
- Insoluble
- (So) no osmotic effect / does not leave cell / does not affect water potential
- Large molecule / long chain
- (So) does not leave cell / contains large number of glucose units
- Branched chains
- (So) easy to remove glucose
An arteriole is described as an organ. Explain why.
-Made of (different) tissues / more than one tissue
An arteriole contains muscle fibres. Explain how these muscle fibres reduce blood flow to capillaries.
- (Muscle) contracts;
2. (Arteriole) narrows/constricts/reduces size of lumen/vessel / vasoconstriction;
A capillary has a thin wall. This leads to rapid exchange of substances between the blood and tissue fluid. Explain why
-Short diffusion distance/pathway;
Blood flow in capillaries is slow. Give the advantage of this.
-(More) time for exchange/diffusion (of substances);
Kwashiorkor is a disease caused by a lack of protein in the blood. This leads to a swollen abdomen due to a build up of tissue fluid. Explain why a lack of protein in the blood causes a build up of tissue fluid.
- Water potential (in capillary) not as low/is higher/less negative / water potential gradient is reduced;
- Less/no water removed (into capillary);
- By osmosis (into capillary);
Classification
-kingdom, phylum, class, order, family, genus, species
These results suggest that leopards are more closely related to cheetahs than to pumas. Explain why.
- More hydrogen bonds (form);
- Similar DNA sequence(s) / similar base sequence(s) / more complementary bases / more base
pairs;
what is meant by a genetic bottleneck
- Drop in population / many killed / only single female left;
- Idea of reduced/low genetic variation/diversity / reduction in (variety of) alleles / smaller gene pool;
What is intraspecific variation?
-Variation / differences within the same/a species;
Explain why both types of twin were used in this investigation. (schitsophrenia)
- Identical twins show genetic influence / differences between them show environmental influence;
- Non-identical twins (also) show an environmental/non-genetic influence;
factors that the scientists should have taken into account when selecting the twins to be used in this study.
- Age;
- Sex (non-identical twins);
- Family/medical history (of mental illness);
- No use of recreational drugs;
- Ethnic origins;
Describe how the students would have returned the air bubble to the start of the capillary tube in this investigation.- potometer
-Open/use tap / add water from reservoir;
precautions the students should have taken when setting up the potometer to
obtain reliable measurements of water uptake by the plant shoot.
- Seal joints / ensure airtight / ensure watertight;
- Cut shoot under water;
- Cut shoot at a slant;
- Dry off leaves;
- Insert into apparatus under water;
- Ensure no air bubbles are present;
- Shut tap;
- Note where bubble is at start / move bubble to the start position;
- Seal joints / ensure airtight / ensure watertight;
A potometer measures the rate of water uptake rather than the rate of transpiration. Give two reasons why the potometer does not truly measure the rate of transpiration.
- Water used for support/turgidity;
- Water used in photosynthesis;
- Water produced in respiration;
- Apparatus not sealed/’leaks’;
