Question 120 marks
Question
(a) Fig. 1.1 shows part of the human gas exchange system. A cartilage B C Fig. 1.1 (i) Identify structures A, B and C shown in Fig. 1.1. A …… B …… C …… [3] (ii) State the function of the cartilage shown in Fig. 1.1. …… [1] (iii) Explain how inspiration occurs. [4] (b) Cystic fibrosis is a condition that affects the lungs. People with cystic fibrosis have mucus in the airways of their lungs that is thicker and stickier than usual. (i) Two types of cells that line the airways protect the body against pathogens and particles. State the names of these two types of cell and describe how they protect the body. …… [3] (ii) Suggest how having thicker and stickier mucus in the airways affects the ability of a person to do exercise. …… [4] (c) Cystic fibrosis is an inherited condition in humans caused by a recessive allele of a gene. There are two alleles for this gene: • the allele for no cystic fibrosis is represented by the letter F • the allele for cystic fibrosis is represented by the letter f. Two heterozygous parents wanted to have a child. Complete the genetic diagram to predict the probability of these parents having a child with cystic fibrosis. parental phenotypes no cystic fibrosis x no cystic fibrosis parental genotypes …… x …… gametes …… , …… x …… , …… offspring genotypes …… …… …… …… offspring phenotypes …… …… …… …… probability of having a child with cystic fibrosis …… [5] [Total: 20]
Mark scheme
1(a)(i) A trachea ; 3 B bronchus / bronchi ; C bronchiole(s) ; 1(a)(ii) to keep the airway open / prevents collapse (of airway) ; 1 1(a)(iii) any four from: 4 1 diaphragm, contracts / flattens / lowers ; 2 external intercostal muscles contract (and internal intercostal muscles relax) ; 3 ribs / ribcage, lifted / AW, up / out / forwards ; 4 increase the volume, in the thorax / lungs / chest ; 5 decreasing the pressure, in the thorax / lungs / chest ; 6 air is drawn in to equalise the pressure (between atmosphere and A air pressure lower than atmospheric lungs) ; pressure / air moves in down a pressure gradient 1(b)(i) 1 any two named cells from: 3 • goblet (cells) • ciliated (cells) • lymphocytes • phagocytes plus any two from: 2 goblet cells, secrete / produce, mucus to trap, particles / pathogens / AW ; 3 cilia on ciliated cell, move / AW, mucus, up / out / away / AW ; 4 lymphocyte produces antibodies ; 5 phagocyte carry out phagocytosis OR engulf, pathogens / particles / AW ; 1(b)(ii) any four from: 4 1 blockage / narrowing of, airways / lumen / AW ; 2 reduced, diffusion / surface area (for gas exchange) ; A increased diffusion distance 3 ref. to less / slower, (delivery of) oxygen / (removal of) carbon dioxide / gas exchange ; 4 into, blood / muscle ; 5 less (aerobic) respiration / (more) anaerobic respiration ; ora 6 less energy (released) / ATP (produced) ; ora 7 for muscle contraction ; 1(c) 1 correct parental genotypes: Ff and Ff ; 5 2 correct gametes: F, f and F, f ; 3 correct offspring genotypes: FF, Ff, (Ff), ff ; A genotypes in any order 4 correct offspring phenotypes: no cystic fibrosis and no cystic fibrosis (no cystic fibrosis) and MP4 offspring phenotypes must be in the same cystic fibrosis ; order as offspring genotypes 5 probability: 0.25 / 25(%) / 1 out of 4 / 1:3 ; ecf from previous step