1 the Diagram Shows a Laboratory Model of the Digestive System

A5 Taking it in Homework

HELP

1 The diagram shows a laboratory model of the digestive system.

Y Add amylase solution X from a beaker

Pestle and mortar Funnel connected to rubber tube

Clip Syringe to inject B enzyme mixture W Z Clip Clip

Plastic bag C D Leg from a pair of tights

E Clip F

a Use words from the list below to label the parts from A–F, shown above. anusanus gulletgullet stomachstomach mouthmouth

smallsmall intestineintestine largelarge intestineintestine

b i What substance, which is represented by label X and contains amylase, is made in the mouth? ii What substance is represented by label Y? c What is produced, in a person, from the part labelled F on the model? d Copy and complete the following sentence:

The pair of tights is a good model for this part of the digestive

system because .

CORE

Look again at the model shown for question 1. 2 a What is not represented, around the outside of parts D and E, that is important for getting absorbed nutrients round the body? b i What is not represented, on the inside of parts D and E, that is important for absorption? ii Explain how this structure helps absorption to happen efficiently. c i Which substance is absorbed in part D? ii Which substance is absorbed in part E? d i What is the main component of the material at point F? ii Why is this substance not absorbed? e i Name one type of nutrient that does not have to be digested before it is absorbed. ii Why does the nutrient you have named not need to be digested?

EXTENSION

Look again at the model shown for question 1. 3 a What is the function of the enzymes that are injected, in the model, at point Z? b Structure C, in real life, churns and squashes its contents for a few hours before moving them on to part D. Suggest why this is important. c Gupta’s saliva does not contain amylase. His small intestine does not make carbohydrase either. i Why should Gupta avoid eating too many starchy foods? ii What sort of food should Gupta eat, to make sure his body gets the energy it needs? iii How might Gupta feel, if he does not eat the right sort of food? 4 a Which molecule is the main component of the material produced by humans at point F? b Why are humans not able to digest this molecule? c Some animals can digest this molecule. How do they do it? d On the model, the clip at point W represents a ring of muscle called a sphincter. A sphincter squeezes a tube to close it tightly shut. Anne is a gymnast. Suggest why it is very important, for Anne, that her sphincter is working properly.