Fig. 2.1 is a photograph of a villus from one part of the small intestine. Fig. 2.1 (i) The length of line $$$\mathbf{A B}$$$ represents the width of the villus in Fig. 2.1. Measure the length of line AB. length of line $$$\mathbf{A B}$$$ ......................................... mm Use your measurement and the formula to calculate the actual width of the villus. $$\[ \text { magnification }=\frac{\text { length of line } \mathbf{A B} \text { in Fig. } 2.1}{\text { actual width of villus }} \]$$ Give your answer to two significant figures. Space for working. ..................................................... mm (ii) Fig. 2.2 shows a villus from a different part of the small intestine. Fig. 2.2 State two ways the villus in Fig. 2.2 differs from the villus in Fig. 2.1. 1 ..................................................................................................................................... ....................................................................................................................................... . 2 ..................................................................................................................................... ....................................................................................................................................... .

Biology

IGCSE&ALevel

CAIE

Exam No：0610_w24_qp_53 Year：2024 Question No：2(a)

Answer:

Knowledge points:

2.3.1 Calculate magnification and size of biological specimens using millimetres as units

2.3.2 Calculate magnification and size of biological specimens using millimetres and micrometres as units

7.2.1 Define ingestion as the taking of substances, e.g.

7.2.10 Describe cholera as a disease caused by a bacterium

7.2.11 Identify the main regions of the alimentary canal and associated organs, limited to mouth, salivary glands, oesophagus, stomach, small intestine (duodenum and ileum), pancreas, liver, gall bladder and large intestine (colon, rectum, anus)

7.2.12 Describe the functions of the regions of the alimentary canal listed above, in relation to ingestion, digestion, absorption, assimilation and egestion of food

7.2.13 Explain that the cholera bacterium produces a toxin that causes secretion of chloride ions into the small intestine, causing osmotic movement of water into the gut, causing diarrhoea, dehydration and loss of salts from blood

7.2.2 food and drink, into the body through the mouth

7.2.3 Define mechanical digestion as the breakdown of food into smaller pieces without chemical change to the food molecules

7.2.4 Define chemical digestion as the breakdown of large, insoluble molecules into small, soluble molecules

7.2.5 Define absorption as the movement of small food molecules and ions through the wall of the intestine into the blood

7.2.6 Define assimilation as the movement of digested food molecules into the cells of the body where they are used, becoming part of the cells

7.2.7 Define egestion as the passing out of food that has not been digested or absorbed, as faeces, through the anus

Answer:

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