Answers

Objective Questions1C2D3D4C5D/r\7B8B9A10D11 C12C13D

t4AlsB16817818C19B20A2tA22B23D24D251'

Structured Questions1 (a) (i) Protein

(ii) Carboh-1-drate(iii) 100% - (62.4 t 7 *'t i.q%- 100% - 80.4% = 19.60/o

(b) RoughageThe roughage stimulates peristalsis and prevents the stool from becoming hard.

(c) 1 Alkaline characteristics - prepares a medium that is suitable for enzl-maticaction2 Acts as the fat emulsif ing agent

(d) The action of the lipase produces fatfy- acid- ivtich has acidic characteristics toneutralise the alkaline condition of the mixlure in the test tube

(e) Packaged milk because its digested producis take a longer time to neutralise thecontents ofthe test tube

2 (:a) (i) Teenage boys are nearl-v at the end of ..'heir bone and teeth gror,vth comparedwith children who need more vitamin D to help in calcium absorption forthe formation of strong bone and teeth.

(ii) Teenage boys are more active compared with children; as such teenageboys need more iron nutrients to build haemoglobin for oxygen transportto the muscle for energy release.

(iii) Teenage girls experience menstruation every month. As such, they requiremore iron nutrients than teenage boys, to replace the loss of blood.

(bxi) Dailv protein requirement per kg of bodv mass +, i- ).1 Jlrs

(ii) Daily protern requrement per ks of bodv mass q '' isilr4'T6 -J

(c) (i) Children require twjce the amount of protein compared with teenage boysbecause children are in the a stage of active growth, where protein isrequired to build new cells, while teenage boys only require protein to repairdamaged tissues onl1,.

(i1) Meat/soya bean contains all the required amino acids. Eating one type ofvegetable will not provide all the required amino acids.

(d) 1 Roughage2 Water

Essay Question(a) The meaning offood digestion - Break up / hydrolyse big and complex food

molecules into small and simple molecules through the action of enzymes.

The meaning of food absorption - Small and digestecl food molecules diffusefrom inside the intestine into the blood vessels

(b) Pancreas secretes pancreaticjuice that has alkaline properties in order to prepare asuitable medium for enzymatic action. Pancreatic juice contains (i)

- amylase

elzvme that acts on the starch to produce maltose, (ii) lipase enzyme that acts onthe fat to produce fattl'- acids and glycerol. (iii) trypsin enzyme that hydrolysespeptone and polvpeptide into peptides.

(c) Hypothesis: Young mice is grven vitamins in their rnilk grow faster than youngmice that are not given this nutrition.Plan of experiment:Number of mice: 25 - 30 mice per groupCreate tu'o groups.Group 1: Gven milk contairung vitaminsGroup 2: Gven milk rvithout vitaminsVariable that: is manipulated - vitamin content in the milk; responds - increase inthe growth rate (measured in mass). are kept constant - species, age, sex,sun'oundings, and milk qualit-v

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Answers

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Objective Questions

ABCDCBDC

2 (i)

branched

9A10c11 A12D13D14D15Bt6B

body cell

Structured Questions

1 (a) To control the alr temperature in test tubes p and e so that it is at 25"c

(b) Woodlice breathes by absorbing oxygen and releasing carbon dicxide. Carbondioride is absorbed b1- the potassium hvdroxide solution causing the air pressure intest tube P to decrease and become lower than the air pressure in test tube Q. Assuch, the level of the manometer liquid rises in the arm that is connected to test tube

(c) The level of the manometer liquid rises higher because the rate of oxvgen intake inthe cockroach is faster than in the woodlice.

(d)

Facheole

(b) (i) Atmospheric carbon dioxide content is lower compared with the air that isbreathed out

(ii) The breathing rate increases after carr5,ing out physical activities an,J the rate ofcarbon dioxide release increases

Breathine out Breathrins irrFlaskA None Air bubblesFlask B Air bubbles None

Essay Question

(a) (i) Anaerobic respiration is the breakdown of glucose in the absence of orygen - Thisprocess occurs in yeast and certain bacteria

(it) The differences between anaerobic respiration and aerobic respiration:1 In anaerobic respiration, glucose is not fully broken down, and part of the energy

is still stored in the ethanol molecule - As such. the energi, released fromanaerobic respiration differs little from aerobic respiration.

2 Anaerobic respiration does not require oxi'gen compared i,l'ith aerobic respirationthat requires o,V-gen.

3 The product of glucose decomposition from anaerobic respiration is ethanol/lacticacid. This is different from the products in aerobic respiration, whrch ale carbondioxide and \,vater.

(b)

Pathwav Method of transportationNose, Phary.nx. Larynx. Trache4Bronchus. Bronchiole

Breathins in

Alveolus to the blood capillan DiffusionVenule- pulmonarv vein- heart Unidirectional blood circulation guided by

the crescent valve in the vein

Carbon dioxi<ie gas molecules breathed out b1'humans ) atmosphere ) diffusion )enters the leaf through the stoma opening ) diffusion in the arr spaces betu.een thesponge mesophy'll cells ) enters the mesoph-vll cell ) photosynthetrc process in themesoph-vll ceil ) dark stage ) carbon ciioxide is reduced by hydrogento form glucose

(c)