O-LevelBiologyHuman Nutrition5090/21 · May/June 2022 · Q710 Marks

The diagram shows a section through a molar tooth of a human. enamel dentine pulp made of living tissue containing sensory nerve endings and blood capillaries

(a)(i)State the function of a molar tooth.[1]
(a)(ii)The pulp is a living tissue. Describe the movement of molecules in the pulp between the blood capillaries and the cytoplasm of the surrounding cells.[4]
(b)Toothache is caused by inflammation of the pulp tissue and is often a sign of dental decay. Describe the cause of dental decay and how it can be prevented.[5]

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Mark scheme

Marking points from the official mark scheme (May/June 2022). The mark or mark type is shown in brackets.

[1] crushing /grinding / chewing / increasing surface area of food ;
[4] any four from: blood under pressure ; capillary + thin wall /one cell thick ; soluble materials / plasma + squeezed / leaks out ; oxygen / glucose + from capillary / to cells ; carbon dioxide / urea + from cells / to capillary / blood ; diffusion; across cell membrane / partially permeable + membrane ; additional named soluble substance e.g. amino acids + direction of movement;
[3] any three from: bacteria; bacteria + feed on + sugar / food; produce acid; acid + corrodes / destroys AW + enamel / dentine ;
[2] any two from: brushing / cleaning / toothpaste ; flossing/mouthwash ; fluoride; avoid sugar AW ; visit dentist;

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