Home / A level Biology 9.1 The gas exchange system – Exam style question – Paper 2

A level Biology 9.1 The gas exchange system – Exam style question – Paper 2

Question [Maximum marks: 5]

Name as precisely as you can the structure described in each of the following statements.

(a) The blood vessel that transports deoxygenated blood from the heart.

(b) The cell that ingests and digests cell debris and bacteria in the lungs.

(c) The cell that secretes antibodies.

(d) The epithelial cell that secretes mucus in the trachea.

(e) The tissue that prevents the collapse of the trachea during inhalation.

Answer/Explanation

Answer:      (a) pulmonary artery ; A pulmonary arteries 

(b) phagocyte / macrophage ;
                A neutrophil / polymorphonuclear leucocyte R PMN
                R leucocyte / white blood cell unqualified
                R any incorrect qualification 

(c) B-lymphocyte / (effector) B (cell) / plasma (cell) ; R lymphocyte alone
                 R effector cell unqualified 

(d) goblet (cell) ;

(e) cartilage ; ignore plates / rings

Question

(a) Explain how uncontrolled cell division can result in cancer. [3]

(b) Describe the experimental evidence that shows that smoking causes lung cancer. [3]

(c) Fig. 6.1 shows the changes in mortality rates for lung cancer in five countries between 1950 and 2006 for males.

        With reference to Fig. 6.1, describe the similarities and differences in the trends in mortality rates in the countries shown. [3] [Total: 9]

Answer/Explanation

Ans:

6 (a) ref. to mutation(s) ;
                   in context of initiating uncontrolled mitosis OR as a consequence of uncontrolled mitosis
           proto-oncogenes convert to oncogenes / oncogenes switched on/ tumour suppressor genes switched off ;
           (cell division is by) mitosis ;
           formation of, tumour/mass of (unspecialised) cells ;
           no response to (extracellular/ intracellular) signals to control mitosis /AW ;
           no contact inhibition/AW ;
           no cell death/ no apoptosis ;
           immune system does not recognise the cells as foreign and destroys them ;
                   A reference to, not non-self/ self
           metastasis / described ;

     (b) R way in which cancer develops /epidemiological evidence
           A beagles for dogs

           1 tar painted on skin of, mice/rabbits /rats /(small) mammal, led to development of (cancerous / malignant) tumour ;
           2 dogs that smoked (plain) cigarettes developed, cancer/ tumour ;
           3 dogs that smoked filter-tipped cigarettes did not develop cancer/ tumour ;
               A developed precancerous changes
           4 control group/ dogs, which did not smoke and did not develop, cancer/ tumour ;
           5 AVP ;
                     e.g. evidence from any other named mammal
                     e.g. inhaling substances from, tar/ tobacco

     (c) similarities
           1 all (named) countries, increase and decrease/reach a peak and decrease ;

           differences
           2 peaks /AW, have occurred at different years in at least two countries ;
           3 all maximum mortality rates are different ;
           4 any comparative, data quote/ calculation, with units given at least once ;
                      e.g. dates and mortality rates for at least two countries
                      e.g. mortality rates for one country at two different dates

           accept a range or a single figure within the ranges given

Question

(a) Tuberculosis (TB) and chronic obstructive pulmonary disease (COPD) are diseases that affect the lungs.

          With reference to TB and COPD, explain how infectious diseases differ from non-infectious diseases.[2] 

          Macrophages are large phagocytic cells that are found in many tissues including alveolar tissue in the lungs. They provide the main means of defence against pathogens in this tissue.

          Fig. 3.1 is a drawing made from an electron micrograph showing part of a capillary and two alveoli, with a macrophage.

   (b) With reference to Fig. 3.1, explain:

          (i) how alveoli are adapted for gaseous exchange.[3]

          (ii) how macrophages function to protect the lungs from becoming infected.[4]

   (c) Phagocytes release enzymes that digest proteins. In smokers, this may lead to the large-scale destruction of alveolar walls.

           Outline the effects of this destruction on a person’s health.[3] [Total: 12]

Answer/Explanation

Ans:

3 (a) max 1 if no ref. to TB and COPD or if correct definitions given and ref. to TB/COPD incorrect (TB is an infectious disease, COPD non-infectious)

           TB caused by, a pathogen/Mycobacterium/ M. tuberculosis / M. Bovis ; ora for COPD
                     A microorganism/ bacterium/ bacteria I virus / fungus /protoctist
                     A infectious disease is caused by a pathogen ora

           TB is /COPD is not, transmissible/ communicable/ can be passed from one organism to another ; allow detail of TB transmission e.g. droplet infection / in contaminated milk
                     A infectious disease is transmissible ora

           COPD caused by, damage to/ irritation of, lung tissue ; AW
                     accept relevant ref. to tobacco smoking

   (b) (i) 1 lining/ epithelium/wall, is thin/ one cell thick / squamous ;
                               I thin interstitium
                               R cell walls of alveoli
                               R alveoli are one cell thick
                               R endothelium/ membrane

                  2 (so) short diffusion distance/only diffuse through two cells ;

                  3 (collectively / many, so) large surface area for diffusion ;
                                R an alveolus has a large surface area
                                               I high SA:V ratio/ increase SA

                  4 surrounded by /many / network of, capillaries ;
                             I good blood supply

                  5 red blood cells are very close to air (in alveoli) ;

                  6 (so) maintain, diffusion/ concentration/ partial pressure, gradient(s) ;

                  7 elastin / elastic fibres, allow(s) alveoli to, increase in volume/ expand/ stretch/ stop bursting/recoil ;
                                  I alveoli are elastic
                                  R contract

          (ii) allow microorganisms or named type of microorganism or infectious agent for pathogens
                  1 recognise, non-self/ foreign, antigens, (on pathogen) ;
                  2 receptors (on macrophage) bind antigens (on pathogen) ;
                  3 (or), pathogen/AW, adheres / ‘sticks’, to (cell surface) membrane ;
                  4 infolding of (macrophage cell surface) membrane around/ engulf/ phagocytosis of, pathogen ; R engulf antigen
                  5 vacuole/ vesicle/ phagosome, forms ;
                  6 ref. to lysosomes ;

                  7 hydrolytic / digestive/named, enzymes ;
                                  e.g. lysozyme/ protease/ nuclease
                                  A pathogen broken down by enzymes

                  8 hydrolysis of named compound(s) ;

                  9 ref. to destroying/ killing, pathogen ;

                  10 ref. to antigen presentation ;
                                accept idea even though does not occur in alveoli   

   (c) 1 emphysema ;
           2 (alveolar walls broken down so) less surface area for, gas exchange/ diffusion ;
                      A impaired/AW, gas exchange/diffusion

           3 difficulty in breathing/restriction in air flow/ shortness of breath wheezing/rapid breathing ;
           4 blood is less well oxygenated/ less oxygen reaches, tissues /muscles ;
           5 any two other, signs / symptoms ;;

           6 e.g. lethargy / tiredness / fatigue/ constraints on mobility or activity wheezing
                      persistent/AW, coughing
                      chest tightness ; R chest pain
                      more prone to/ frequent, chest/respiratory, infections
                                 A more frequent colds / influenza (‘flu)
                      weight loss
                      swollen, ankles / feet
                      increase in thickness of, right ventricle/right side of heart
                      increase in blood pressure in pulmonary artery  

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