A-LevelBiologyGas exchange9700/22 · Oct/Nov 2020 · Q37 Marks
Fig. 3.1 is a photomicrograph of a section through lung tissue. [Figure 3.1]
- (a)State the feature visible in Fig. 3.1 that identifies the structure in the centre of the image as the bronchus and list other visible features that help to confirm this identification. feature to identify the bronchus other features[3]
- (b)Identify the structure labelled J in Fig. 3.1. State the evidence visible in Fig. 3.1 that supports your answer.[2]
- (c)The ciliated epithelium labelled in Fig. 3.1 consists of goblet cells and ciliated epithelial cells. Outline how goblet cells and cilia work together to maintain healthy lung tissue.[2]
This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2020). The mark or mark type is shown in brackets.
- [3] irregular / plates / AW, of cartilage ; A cartilage not C-shaped rings
- other features
- any two from:
- smooth muscle ;
- elastic, tissue / fibres ;
- mucous glands ;
- thick wall/wall many layers ;
- large lumen (relative to thickness of wall) ;
- large size relative to surrounding alveoli; I surrounded by alveoli
- [2] evidence must match stated structure
- blood vessel ;
- plus any one from:
- presence of tunica media / circular layers of smooth muscle ;
- three layers in wall;
- similar to structure on left, which has blood cells ;
- not bronchiole, qualified; e.g. as no ciliated epithelium
- OR
- artery ; A arteriole
- plus any one from:
- small lumen relative to thickness of wall ; A small lumen with thick wall
- thick, tunica media / muscle layer;
- thick tunica externa ;
- OR
- vein ;
- plus any one from:
- no definite shape / not rounded / not oval / AW ;
- large lumen relative to thickness of wall / large lumen and thin wall;
- thin tunica media;
- [2] goblet cells, produce / secrete / AW, mucus to trap, pathogens / AW ;
- A dust/dirt/particles etc for AW
- cilia, waft / moves / carries / push, mucus, to back of throat/AW;
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