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BIOLOGY SPM ESSAY QUESTION COLLECTIONS Movement of Substances across the Plasma Membrane SBP 2011 1 (a)


Movement of substances across the plasma membrane in the cell is important for the continuity in life of organisms. The process helps to maintain a constant internal environment. (i) Explain the importance of plasma membrane for the survival of living organism. [4 marks] living organism need nutrients / oxygen / glucose / mineral / any suitable example to continue their life`s processes ions inside cells must be kept at different concentration to outside the cells. to maintain a constant internal environment/ (homeostasis) The substances across the plasma membrane from the external environment cells produce waste products which exit through the plasma membrane The movement / types / amount of substances in and out of the cells is regulated by plasma membrane. the cells need to maintain suitable pH of the cells for enzyme activity so that cell can secretes useful substances / hormones / enzymes


Diagram 1.1 shows two types of transport of substances through plasma membrane.

Diagram 1.1 Explain the two types of transport of substances through plasma membrane shown in Diagram 1.1. [6 marks] Type 1 facilitated diffusion occur diffusion of small molecules / ions move from higher concentration to the higher concentration of solute through pore protein does no need energy



Type 2 Active transport occur The molecules such as sodium ions / potassium ions / glucose / amino acid move against concentration gradient / from lower concentration to the higher concentration through carrier protein have active site with bind with particular molecule need energy / ATP (b) A student carry out the experiment to determine the concentration of an external solution which is isotonic to the cell sap. The student immersed the potato strip in a different concentration of sugar in 30 minutes time. Diagram 1.2 shows graph plotted to show the change in mass against concentration of solution.

Diagram 1.2 (i) Based on the graph in Diagram 1.2, state the concentration of the solution that is isotonic to cell sap. [1 mark] 2

BIOLOGY SPM ESSAY QUESTION COLLECTIONS Isotonic to the sap cell: 0.27 mol dm-3/ 0.28 mol dm-3/ 0.29 mol dm-3 (ii) Explain what happen to the cell at point P , Q and R.


[9 marks] Point P The mass of potato increase (This occur because) the solution concentration is hypotonic to the sap cell of the potato The water molecule diffuse out from lower concentration/ hypotonic region to the higher concentration/ hypertonic region by osmosis cell becomes turgid (so the mass increased) Point Q The potato does not lose or gain mass This occur because the concentration o the solution is isotonic to the cell sap Diffusion of water molecule is at equilibrium / equal rate no net gain or loss of water molecule (so the mass is maintained) Point R The mass of potato decrease (This occur because) the solution is hypertonic to the cell sap The water molecule diffuse out from cells / from higher concentration to the lower concentration / solution at surrounding by osmosis cell becomes flaccid (so the mass decreased)


BIOLOGY SPM ESSAY QUESTION COLLECTIONS Nutrition SBP 2011 1 (a) Diagram 1.1 show the digestive system of a herbivore.


Diagram 1.1 Describe how cellulose in the plant fibres are digested and how the products of digestion of cellulose are absorbed into the body of the herbivore. [10 marks] How cellulose in the plant fibres are digested This is the digestive system of a non ruminant example a rabbit. Mouth: Plant tissues are cut, crushed and grind by the teeth / incisors / premolars / molars. Plant cell walls are disrupted / cellulose exposed Stomach / duodenum / ileum No enzyme cellulase secreted / No digestion of cellulose. Caecum (Enlarged )/ contains microorganisms / bacteria / protozoa which secrete cellulase to digest the cellulose Appendix Enlarged / contains mi.croorganisms / bacteria / protozoa which secrete cellulase to digest the cellulose. Cellulase hydrolyse cellulose to glucose in the caecum and appendix Absorption of glucose Some glucose are absorbed by the caecum. No absorption of glucose in rectum Re-swallow the digested cellulose/glucose / pallet from the caecum after it has left the anus / coprophagy All the glucose is absorbed into the blood capillaries of the villus in the ileum


BIOLOGY SPM ESSAY QUESTION COLLECTIONS (b) Diagram 1.2 shows a food pyramid.


Diagram 1.2 Based on Diagram 1.2, explain how a teenager may be able to plan his daily diet wisely to maintain his normal growth and good health. [10 marks] A good dietary habit for normal growth and good health of an adolescent: practicing a daily balance diet the diet comprises all food classes // carbohydrates, lipoids, proteins, vitamins, mineral salts and fibers // foods from level 1, level 2, level 3 and level 4. in the correct amount should take more foods from level 1, 2 and 3 / containing carbohydrates, fruits and vegetables / proteins for sustaining better general body growth / normal metabolism of the body. the adolescent requires more carbohydrates (as level 1) for example energy production / energy resources in the body More proteins (as level 3) for rapid muscular growth / replacement of dead tissues / cells / repairing damaged cells and synthesis of functional proteins/ enzymes / antibody /hormones / insulin vitamins / minerals serve as co-enzyme / co-factor for normal enzyme activities elements like Ca/ P / iodine are important for growth of bones / teeth / development of endocrine gland / thyroid fibers helps peristalsis in the alimentary canal / avoiding constipation should avoid from consuming excessive fats (as level 4) which is the principal cause of cardiovascular problems / heart problem / hypertension / thromboses coronary / arterosclerosis / obesity


BIOLOGY SPM ESSAY QUESTION COLLECTIONS Kedah 2011 2 Diagram 2.1 shows a food pyramid.


Diagram 2.1 (a) Explain why ice cream, butter cake are placed at level 4 in the food pyramid. [6 marks] (b) Food at level 4 should only be taken in smallest amount / ratio. Ice cream contain a lot of sugar. Sugar has high energy value. Excessive sugar in the body will lead to obesity / diabetes. Butter cake contain a lot of lipid. Lipid has high energy value. Excessive lipid will form adipose tissue in the body // increase cholesterol level in body. (Excessive lipid will) lead to heart attack / cardiovascular disease / stroke.

Explain the importance of consuming food from level 2 in our daily diet. [4 marks] Food at level 2 contains a lot of water, vitamins, minerals and roughage / fibre. Water is important in all cell activities / physiological / biochemical processes in our body. Body need enough vitamins to preserve / maintain health // Any suitable example of vitamin and the related function Body need enough minerals to preserve / maintain health and growth // Any suitable example of mineral and the related function. Roughage is necessary in the diet to stimulate peristalsis / to prevent constipation.


Diagram 2.2 shows a few examples of fresh food and processed food.

Diagram 2.2

BIOLOGY SPM ESSAY QUESTION COLLECTIONS Discuss the good effects and bad effects of processed food in our daily life.


[10 marks] Good Effect : By producing processed food Food can be preserved / kept longer. to prevent food poisoning / wasting of food. Crops can be planted / livestock / poultry can be reared in big scale. to prevent food shortage. (food are packaged) to increase the commercial value / easier to be transported. more types / varieties of food can be produced.

Bad Effect : By regular consuming of processed food SBP 2010 3 (a) Diagram 3.1 shows three processes involved before the food substances taken in areable to be incorporated into the body cells of humans. Loss a lot of nutrition value (under high temperature during the process). (Contain) preservative / colouring / dye / flavour which is carcinogenic. lead to mutation / cancer / health problem / suitable example. Contain excessive salt / sugar. lead to high blood pressure / diabetes / obesity

Diagram 3.1 Explain the digestion of butter before it is absorbed by P. [4 marks] (b) (Butter) contains lipids / fats Digestion occurs in the duodenum / ileum The bile salts emulsify the fats / turn into tiny droplets (Catalyses by enzyme) lipase By hydrolysis Fat into fatty acids and glycerol

Describe the absorption and assimilation of the food taken in during breakfast. [10 marks] Absorption 7

BIOLOGY SPM ESSAY QUESTION COLLECTIONS Products of digestion; glucose, amino acids, fatty acids and glycerols. Glucose and amino acids enters the blood capillaries of villi Fatty acids and glycerols enters lacteal of villi Assimilation (i) Glucose Used by cells to produce energy // Cellular respiration Excess glucose is converted into glycogen And stored in the liver / muscles (When liver is saturated with glycogen) glucose is converted into fats. (ii) Amino acids Used to make proteins / enzymes / cell cytoplasm / muscle cells Used in growth / cell repairs Excess amino acids converted into urea And eliminate in the urine Excess may be converted into fats


(iii) Fats Used in building plasma membrane / cell membranes Excess fats are stored in adipose tissues (c) About 50% of the small intestine of a man is cut and removed due to cancer. Explain the effect to the function of structure P and to the amount of stored carbohydrates in his organ Q. [6 marks] To the function of villi Les