BIOL1 Flashcards
in these patients, the right ventricle still produces sufficient blood flow to keep the patient alive. suggest why the left ventricle requires the help of the artificial heart but the right ventricle does not. (2)
- left ventricle pumps to whole body
- left ventricle produces a greater pressure
the pulse felt in the artery in the wrist can be recorded and used to measure heart rate. suggest why the pulse can be used to measure heart rate. (2)
- caused by pressure
- from one contraction of left ventricle
the portable heart rate monitor recorded the men’s heart rates continuously. this gave more reliable mean heart rates than those obtained by recording the pulse in the wrist for 1 minute. suggest why it is more reliable (2)
- monitor records over long period of time
- anomalies in recording have less effect
people with AIDS die because they are unable to produce an immune response to pathogens. explain why this leads to death. (3)
- susceptible to other pathogens
- pathogens reproduce
- damage cells
HIV rapidly enters host cells. explain why that a vaccine might not be effective against HIV. (2)
- HIV enters cells before antibodies can bind to it
- antibodies cannot enter cells
HIV shows a lot of antigenic variability. explain why that a vaccine might not be effective against HIV. (2)
- antigen on HIV changes
- antibody can no longer bind to new antigen
describe the induced fit model of enzyme action. (2)
- active site not complementary
- active site changes
- change in enzyme allows E-S complexes to form
describe one way that the lock and key model is different from the induced fit model. (1)
- active sire does not change shape
explain, interms of pressure, why the semilunar valves open. (1)
- pressure is greater in ventricle than artery
when a wave of electrical activity reaches the AVN, there is a short delay before a new wave leaves the AVN. explain the importance of this short delay. (2)
- allows ventricles to fill
- before ventricles contract
before reweighing the student blotted dry the outside of each potato cylinder. explain why. (2)
- water will affect the mass
- amount of water on cylinders varies
the student calculated the percentage change in mass rather than the change in mass. explain the advantage of this. (2)
- allows comparison
- cylinders have different starting masses
the student carried out several repeats at each concentration of sodium chloride. explain why the repeats were important. (2)
- allows anomalies to be identified
- makes mean more reliable
The vaccine is made from HPV types 16 and 18. explain why this vaccine may not protect against other types of this virus. (3)
- other HPV types have different antigens
- no memory cells for other types
- antibodies not complementary
3 injections of the vaccine are given. use your knowledge of immunity to suggest why. (3)
- More antigen;
- More memory cells;
- So antibodies produced quicker if infected
it will be many years before it can be shown that this vaccination programme has reduced cases of cervical cancer. suggest 2 reasons why. (2)
- cancer takes years to develop
- only teenagers vaccinated
smear tests will continue to be offered to women, even if they have been vaccinated. suggest why women who have been vaccinated still need to be offered smear tests. (1)
- cervical cancer can be caused by other types of HPV
suggest one reason why vaccinating a large number of people would reduce significantly the spread of HPV through the population. (2)
- virus cannot replicate
- non- vaccinated people more likely to come in contact with vaccinated people
in healthy lungs, a gradient is maintained between the concentration of oxygen in the alveoli and the concentration of oxygen in the lung capillaries. describe how ventilation helps to maintain this difference in oxygen concentration. (2)
- brings in air containing a higher oxygen concentration
- removes air with a lower oxygen concentration
coeliac disease is a disease of the human digestive system. in coeliac disease, the villi are damaged. although people with coeliac disease can digest proteins they have low concentrations of amino acids in their blood. explain why they have low concentrations of amino acids in their blood. (2)
- reduces surface area
- less absorption
the student gave their results as a ratio. what is the advantage of giving the results as a ratio? (2)
- allows comparison
- different starting masses
the students were advised that they could improve the reliability of their results by taking additional readings at the same concentrations of NaCl. explain how. (2)
- anomalies can be identified
- mean to be calculated
the student used a graph of their results to find the sodium chloride solution with the same water potential as the apple tissue. describe how they did this. (2)
- plot NaCl concentration against ratio
- find where the ratio is 1
the students were advised that they could improve their graph by taking additional readings. explain how. (2)
- line of best fit more reliable
- point where line crosses axis is more reliable
give 2 ways in which a pathogen may cause disease when it has entered the body. (2)
- produces toxins
- damages cells
explain why these antibodies are referred to as monoclonal. (1)
- produced from same plasma cell
the cardiac cycle is controlled by the SAN and the AVN. describe how
- SAN initiates heartbeat
- SAN sends electrical impulses across atria causing atrial contraction
- AVN delays impulses
- allowing ventricles to fill before they contract
- AVN sends impulses down Bundle of His
- causing ventricles to contract from base up
scientists have developed vaccines against HPV. one of the vaccines contains HPV antigens. a vaccine can be used to produce immunity to HPV. describe how memory cells are important in this process. (4)
- memory cells produced
- when individual comes into contact with antigen against
- rapid response
- destroys antigen before it can cause harm
some doctors suggested offering HPV vaccines to young men. explain the advantage of vaccinating young men as well as young women. (2)
- prevents males being carriers
- prevents males passing it on
describe how the control group should have been treated. (2)
- same as experimental group
- given placebo
after an infection with chlamydia, cells of the immune system of the mice may attack the heart muscle cells. explain why. (2)
- memory cells against chlamydia antigen are present
- protein on heart muscle similar to chlamydia antigen
- antibodies attack heart muscle cells
some white blood cells are phagocytic. describe how these phagocytic white blood cells destroy bacteria. (4)
- phagocyte attracted to bacteria by chemicals
- engulf bacteria
- bacteria in vesicle
- lysosomes empties lysozymes into vacuole
- bacteria hydrolysed
people who have been fire- breathers for many years often find they cannot breathe out properly. explain why. (2)
- loss of elastic tissue
- less recoil
in area where there are repeated outbreaks of cholera, most people who become infected by cholera bacteria do not become ill. suggest and explain one reason why. (2)
- have produced memory cells
- after previous infection
the concentration of glucose in the blood rises after eating a meal containing carbohydrates. the rise is slower if the carbohydrate is starch rather than sucrose. explain why. (3)
- starch digested by amylase
- maltose digested by maltase
- digestion of sucrose is a single step
scientists believe that it may be possible to develop vaccines that make use of microfold cells. explain how this sort of vaccine would lead to a person developing immunity to a pathogen. (5)
- vaccine contains antigens
- microfold cells bind and present antigen to immune system
- T- cells activate B-cells
- B- cells undergo mitosis
- B-cells produce antibodies
- more antibodies produced faster in secondary response
microfold cells take up the antigens and transport them to cells of the immune system. antigens are not able to pass through the cell- surface membrane of other epithelial cells. suggest 2 reasons why. (2)
- not lipid soluble
- too large
describe how phospholipids are arranged in a plasma membrane. (2)
- hydrophobic tails to inside
- hydrophilic head to outside
cells that secrete enzymes contain a lot of rough endoplasmic reticulum and a large Golgi apparatus. describe how the RER is involved in the production of enzyme. (2)
- RER has ribosomes
- to make protein
describe how the Golgi apparatus is involved in the secretion of enzymes (3)
- modifies protein
- packages into Golgi apparatus
- transport to vacuole
the scientists’ hypothesis was that adding the inhibitor of amylase to the food would lead to a lower blood glucose concentration. use your knowledge of digestion to suggest how the addition of the inhibitor could lead to a lower blood glucose concentration. (2)
- fewer E-S complexes
- no starch digested to maltose
- so less glucose from maltose
- so less absorption of glucose
