BIOL1

Question 1

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)

Answer 1

• left ventricle pumps to whole body

- left ventricle produces a greater pressure

Question 2

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)

Answer 2

• caused by pressure

- from one contraction of left ventricle

Question 3

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)

Answer 3

• monitor records over long period of time

- anomalies in recording have less effect

Question 4

people with AIDS die because they are unable to produce an immune response to pathogens. explain why this leads to death. (3)

Answer 4

• susceptible to other pathogens
• pathogens reproduce
• damage cells

Question 5

HIV rapidly enters host cells. explain why that a vaccine might not be effective against HIV. (2)

Answer 5

• HIV enters cells before antibodies can bind to it

- antibodies cannot enter cells

Question 6

HIV shows a lot of antigenic variability. explain why that a vaccine might not be effective against HIV. (2)

Answer 6

• antigen on HIV changes

- antibody can no longer bind to new antigen

Question 7

describe the induced fit model of enzyme action. (2)

Answer 7

• active site not complementary
• active site changes
• change in enzyme allows E-S complexes to form

Question 8

describe one way that the lock and key model is different from the induced fit model. (1)

Answer 8

• active sire does not change shape

Question 9

explain, interms of pressure, why the semilunar valves open. (1)

Answer 9

• pressure is greater in ventricle than artery

Question 10

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)

Answer 10

• allows ventricles to fill

- before ventricles contract

Question 11

before reweighing the student blotted dry the outside of each potato cylinder. explain why. (2)

Answer 11

• water will affect the mass

- amount of water on cylinders varies

Question 12

the student calculated the percentage change in mass rather than the change in mass. explain the advantage of this. (2)

Answer 12

• allows comparison

- cylinders have different starting masses

Question 13

the student carried out several repeats at each concentration of sodium chloride. explain why the repeats were important. (2)

Answer 13

• allows anomalies to be identified

- makes mean more reliable

Question 14

The vaccine is made from HPV types 16 and 18. explain why this vaccine may not protect against other types of this virus. (3)

Answer 14

• other HPV types have different antigens
• no memory cells for other types
• antibodies not complementary

Question 15

3 injections of the vaccine are given. use your knowledge of immunity to suggest why. (3)

Answer 15

• More antigen;
• More memory cells;
• So antibodies produced quicker if infected

Question 16

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)

Answer 16

• cancer takes years to develop

- only teenagers vaccinated

Question 17

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)

Answer 17

• cervical cancer can be caused by other types of HPV

Question 18

suggest one reason why vaccinating a large number of people would reduce significantly the spread of HPV through the population. (2)

Answer 18

• virus cannot replicate

- non- vaccinated people more likely to come in contact with vaccinated people

Question 19

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)

Answer 19

• brings in air containing a higher oxygen concentration

- removes air with a lower oxygen concentration

Question 20

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)

Answer 20

• reduces surface area

- less absorption

Question 21

the student gave their results as a ratio. what is the advantage of giving the results as a ratio? (2)

Answer 21

• allows comparison

- different starting masses

Question 22

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)

Answer 22

• anomalies can be identified

- mean to be calculated

Question 23

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)

Answer 23

• plot NaCl concentration against ratio

- find where the ratio is 1

Question 24

the students were advised that they could improve their graph by taking additional readings. explain how. (2)

Answer 24

• line of best fit more reliable

- point where line crosses axis is more reliable

Question 25

give 2 ways in which a pathogen may cause disease when it has entered the body. (2)

Answer 25

- produces toxins | - damages cells

Question 26

explain why these antibodies are referred to as monoclonal. (1)

Answer 26

- produced from same plasma cell

Question 27

the cardiac cycle is controlled by the SAN and the AVN. describe how

Answer 27

- 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

Question 28

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)

Answer 28

- memory cells produced - when individual comes into contact with antigen against - rapid response - destroys antigen before it can cause harm

Question 29

some doctors suggested offering HPV vaccines to young men. explain the advantage of vaccinating young men as well as young women. (2)

Answer 29

- prevents males being carriers | - prevents males passing it on

Question 30

describe how the control group should have been treated. (2)

Answer 30

- same as experimental group | - given placebo

Question 31

after an infection with chlamydia, cells of the immune system of the mice may attack the heart muscle cells. explain why. (2)

Answer 31

- memory cells against chlamydia antigen are present - protein on heart muscle similar to chlamydia antigen - antibodies attack heart muscle cells

Question 32

some white blood cells are phagocytic. describe how these phagocytic white blood cells destroy bacteria. (4)

Answer 32

- phagocyte attracted to bacteria by chemicals - engulf bacteria - bacteria in vesicle - lysosomes empties lysozymes into vacuole - bacteria hydrolysed

Question 33

people who have been fire- breathers for many years often find they cannot breathe out properly. explain why. (2)

Answer 33

- loss of elastic tissue | - less recoil

Question 34

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)

Answer 34

- have produced memory cells | - after previous infection

Question 35

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)

Answer 35

- starch digested by amylase - maltose digested by maltase - digestion of sucrose is a single step

Question 36

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)

Answer 36

- 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

Question 37

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)

Answer 37

- not lipid soluble | - too large

Question 38

describe how phospholipids are arranged in a plasma membrane. (2)

Answer 38

- hydrophobic tails to inside | - hydrophilic head to outside

Question 39

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)

Answer 39

- RER has ribosomes | - to make protein

Question 40

describe how the Golgi apparatus is involved in the secretion of enzymes (3)

Answer 40

- modifies protein - packages into Golgi apparatus - transport to vacuole

Question 41

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)

Answer 41

- fewer E-S complexes - no starch digested to maltose - so less glucose from maltose - so less absorption of glucose