7. K.C.S.E 2000 PP1 No.12 The temperature of a person was taken before, during and after taking a cold bath. The results are shown in the graph below (a)Explain why the temperature fell during bath Heat loss by conduction/ convection from the blood vessels The body skin to the cold water, the cooler blood leaving skin enters general circulation cooling the whole body. (b)What changes occurred in the skin that enabled the body temperature to return to normal? Vasoconstriction; thus less blood flowing to the skin reducing heat loss. Sweating ceases heat produced through metabolism. Accept shivering producing heat 8. K.C.S.E 2001 PP1 No.6 Adult elephants flap their ears twice as much as their calves in order to cool their bodies when it is hot. Explain The surface area to volume ratio is higher in calves than in adults; hence adults retain more heat than the young. The surface area to volume ratio is lower in adults than in calves; hence calves loose heat faster than adults. 101
9. K.C.S.E 2001 PP1 No.11 The diagram below represents a mammalian nephron (a) Name the (i) Structure labeled P Efferent arteriole/ vessels (ii) Portion of the nephron between point X and Y Loop of henle (b) Name the process that takes place at point Q Ultra filtration (c)Name one substance present at point R but absent at point S in a healthy mammal Glucose d)The appearance of the substance you have mentioned in (c) above is a symptom of a certain disease caused by a hormone deficiency. Name the (i) Disease Diabetes mellitus (ii) Hormone Insulin (e)State the structural modifications of nephrons found in the desert mammals Small Bowman’s capsule/ Groleruli`; Rej few Bowman’s capsule Long loop of Henle 102
10. K.C.S.E 2002 PP1 No.18 Two persons X and Y drunk volumes of concentrated solution of glucose. The amount of glucose in their food was determined at intervals. The results are shown in the table below: Time Glucose level in blood (Mg / 100cm30 (minutes) XY 0 87 84 15 112 123 30 139 170 45 116 188 60 100 208 90 95 202 120 92 144 150 88 123 On the grid provided, plot graphs of glucose level in blood against time on the same axes. For exchanged axis award maximum 3 marks for points x identity. The scale must however be correct. For graphs on separate axis mark both and award the highest mark. o (a) Axis =2 (b) Scale = 1 (c) (plotting) = 1 (d) curves) = 1 103
Time (minutes) Glucose level in blood (Mg / 100cm30 0 XY 15 30 87 84 45 112 123 60 139 170 90 116 188 120 100 208 150 95 202 92 144 88 123 b) What was the concentration of glucose in the blood of X and Y at the 20th minute? X = 120 + -3) Y = 140 +-3) c) Suggest why the glucose level in person X stopped rising after 30 minutes while it continued rising in person Y. Person X is capable of regulating glucose while person y is likely to be diabetic. X – Insulin d) Account for the decrease in glucose level in person X after 30 minutes and person Y after 60 minutes (3 minutes) X insulin released, excess glucose is converted into glycogen (in liver) must be mentioned if insulin is not mentioned Y Insulin not released, thus the decline is due to glucose being released in urine. e) Name the compound that stores energy released during oxidation of glucose. A.T.P / Adenosine triphosphate f) Explain what happens to excess amino acids and development of plants. Deaminated; resulting in formation of ammonia Ammonia combines with CO2 to form urea ( and H20); Urea is passed out in Urine carbohydrate group is oxidized/ stored as glycogen 11. K.C.S.E 2003 PP1 No.14 (a) Explain how marine fish regulate their osmotic pressure. Swallow plenty of sea water to increase amount of water in the body Have chloride secretory cells in the gills to remove excess salts Eliminate nitrogenous wastes in form of trimthylamine oxide which requires little water for elimination. Few / small glomeruli; thus slow filtration rate in the kidneys. 104
(b) Explain the role of antidiuretic hormone when there is excess water in the human body. Less ADH secreted (by pituitary gland); causing less reabsorption of water in the kidney tubules; thus resulting in dilute urine. 12. K.C.S.E 2003 PP1 No.17 Some students used a model to demonstrate the effect of sweating on human body temperature. Two boiling tubes A and B were filled with hot water. The temperature of water in the tubes was taken at the start of the experiment and then at 5 minutes interval. The surface of tube A was continuously wiped with a piece of cotton wool soaked in methylated spirit. The results obtained are shown in the table below. Time Temperature 0C in tubes (minutes) A B 0 80 80 5 54 67 10 40 59 15 29 52 20 21 47 25 18 46 (a)On the same axes, plot graphs of temperature of water in the tubes against time. o (b)At what rate was the water – cooling in tube A? 80 – 18 = 62; 2.48C /Min 2.5 25 105
c) Why was tube B included in the set up? Control (d)Account for the rate of cooling in tube A. Rate was faster in tube A; because the film of methylated sprit evaporated; removing heat from the tube; (e)State two processes of heat loss in tube b. Convection; radiation (f)What would be the expected results if tube A was insulated? Lower rate of heat loss; (g) What would the insulation be comparable to in: i) Birds Feather ii. Mammals? Fur h) Name the structures in the human body that detect: i) External temperature changes Temperature receptor cells in the skin ii) Internal temperature changes Temperature receptor cells in the hypothalamus 13. K.C.S.E 2004 PP1 No.18 How is the mammalian skin adapted to its functions? (20mks) The skin is made of epidermis and dermis. The epidermis is made up of three layers. The outermost layer is known as cornified layer; made up of dead cells that protect against mechanical damage/ desiccation/ microbes; the granular layer; is made up of living cells that give rise to the cornified layer, the malpighian layer; contain actively dividing cells that rise to new epidermal cells, that contain melanin that protects the skin against ultra violet rays. The dermis has several components; has sweat glands’ sudondic glands that produce sweat; sweat evaporates carrying it with latent of vaporization) thus reducing the body temperature; under cold conditions little/ no. Sweat is produced thus heat is conserved; the sweat contains water/ sodium chloride/ uric acid/ urea; the skin is excretory organ. Has hair, the hair stands erect to trap air when temperature is low to reduce heat loss/ lies flat to allow heat loss when the temperature is high. Has nerve endings, which are sensitive to stimuli/ such as heat/ cold/ pain/ pressure/ touch 106
Has subcutaneous fats/ adipose tissue, that insulate the body against heat loss. Has arteriole; that vasodilate when temperature are high to lose heat by radiation/ convection ( see converse) Has sebaceous gland; which secrete sebum, an antiseptic/ water repellant/ that prevent drying/ cracking of skin/ skin supple Acc blood vessels/ capillaries for arterioles to supply food/ nutrients/ oxygen/ remove excretory products. 14. K.C.S.E 2005 PP1 No.13 The diagram below shows a section through the mammalian skin. (3mks) a) Name the parts labeled E, F and G. E – Malpighian layer F – Nerve cell G – Erector pili muscle b) State two functions in each case of substance secreted by the structures labeled. i) H Excretion of waste products of metabolism from the body e.g. excess water, mineral salts traces of urea, lactic acid etc. Temperature regulation in the body brings a cooling effect through loss of excess heat by evaporation of water. ii) I Keeps the hair and epidermis flexible and water proof Contains antiseptic substances for protection against bacteria. 15. K.C.S.E 2006 PP1 No.4 a) Name the fluid that is produced by sebaceous glands. (1mk) Sebum b) What is the role of sweat in human skin? (2mks) 107 Kills micro organisms Cools the body Getting rid of waste/ excretion. Accept named example e.g. urea, sodium chloride, excess water, uric acid, tactic acid.
16. K.C.S.E 2006 PP1 No.11 State the role of insulin in human body. (1mks) Stimulates conversion of excess glucose to glycogen for storage Enhances break down of glucose; stimulates glucose converts to fats and stored. 17. K.C.S.E 2006 PP1 No.7 Describe how human kidney functions (20mks) The afferent arteriole which is the branch of renal artery supplies blood to glomerulus; the afferent arteriole has a wider diameter than the afferent arteriole; this causes high pressure; leading to ultra filtration. The walls of the blood capillaries are one cell thick hence glucose, amino acids, (vitamins, hormones) salts, (creatinine) urea and water filter into Bowman’s Capsule to form glomerular filtrate; White blood cells/ red blood cells and plasma proteins such as (Globulin, fibrinogen, platelets) are too large to pass through the capillaries: the filtrate flow into the proximal convoluted tubule; where amino acids (vitamin) and all glucose are selectively reabsorbs back into the blood stream. Many mitochondria provide energy for re- absorption of these substances against concentration gradient/ by active transport. The Glomerular filtrate flow into loop of henle. Water in descending loop moves by osmosis into the blood capillaries; sodium chloride is actively pumped from the ascending arm of loop henle into the blood capillaries. The glomerular filtrate flow into the distal convoluted tubule, water is absorbed from distal convoluted tubule into blood capillaries; the glomerular filtrate flows into collection tube/ duct from where more water is reabsorbed into the blood stream. Antidiuretic hormone influences the amount of water reabsorbed (depending on osmotic pressure of blood); the glomerular filtrate from collecting duct now referred to as urine; is emptied into pelvis. The urine passes though pelvis and ureter into bladder out of the body through urethra. 18. K.C.S.E 2007 PP1 No.14 (a) What is the meaning of the terms (i) Homeostatic (1 mark) Internal self adjustments of various conditions such as temperature to optimum levels for the better functioning of the body (ii) Osmoregulation (1 mark) Maintenance of a concentration of water and salts ion the body fluid. ( b) Name the hormones involved in regulating glucose level in blood. Insulin Glucagon (2mks) 108
19. K.C.S.E 2007 PP1 No.2 (a) Explain what happens to excess amino- acids in the liver of humans (3 marks) They are deaminated and taken into ornithine cycle to form urea which is then excreted via urine in the kidney (b)Which portions of the human nephron are only found in the cortex? (3 marks) Glomerulus Bowmans capsule PCT (c) (i) What would happen if a person produced less antidiuretic hormone? (1 mark) Pass large volume of dilute urine (ii) What term is given to the condition described in (c) (i) above (1 mark) Diuresis 20. K.C.S.E 2008 PP1 No.2 State the importance of the following processes that take place in the nephrons of a human kidney (a)Ultra filtration ( 1 mark) To remove toxic/ harmful substances/ urea nitrogenous waste from the blood streams (b)Selective reabsorption ( 1 mark) To return useful substances/ glucose and Amino acids loose into the bloodstream. 21. K.C.S.E 2008 PP1 No.3 (a)Name a disease of the liver whose symptom is jaundice (1 mark) Hepatitis (A- E lipids) (b)State the causative agent of: (i) Cholera (1 mark) Vibria chlerae (underline separately) (ii) Candidiasis (1 mark) candida albicans (underline separately) 22. K.C.S.E 2008 PP1 No.11 (a)What is homeostasis? ( 1 mark) Ability of organism to maintain a stable/ constant internal/ tissue fluid 109
(b)Name three processes in the human body in which homeostasis is involved (3 marks) Gaseous exchange Thermoregulation Osmoregulation Regulation of blood sugar Regulation of pH of tissue fluid. 23. K.C.S.E 2008 PP1 No.26 State one use of the following excretory products of plants. (a)Colchicines Inducing polyploidy/ treatment (b) Papain Meat tendelizer 24. K.C.S.E 2009 PP1 No.17 Explain why plants do not require specialized excretory organs 4 marks) Some wastes e.g gases easily diffuse out. Waste products are mainly made from carbohydrate and (NB: must mention some/most) hence are not as harmful as proteineous materials Waste products are formed slowly/little accumulation of wastes/ plants are leas active Some waster products (such as 02 and are usable- recycled Some waste products are store in non- toxic forms in leaves, flowers, fruits and old bark 25. K.C.S.E 2009 PP1 No.21 Explain what happens in humans when concentration of glucose in the blood decreases below the normal level ( 4 marks) Pancreases releases glucagon to stimulate liver cells to convert stored glycogen to glucose; fat converted to glucose/ reduces rate of respiration. Rej if source of glycogen is the liver. 26. K.C.S.E 2002 PP2 No.8 Describe the role of the liver in homeostasis in the human body (20 marks) o Regulation of blood glucose The normal amount of glucose in the blood is 90 mg/ 1000m3 increase in blood sugar level is detected by cell of the (batacelss) pancreases, which secrete insulin; insulin stimulates the liver to convert excess glucose to glucogen. Further excess glucose is converted to fats. Excess glucose is also oxidized to energy (carbon IV) oxide & water/ respiration. 110
Decrease in blood sugar level below the normal level is detected by the (alphacells) by the pancreases. Which secretes glucogen that stimulates the liver, to convert glucogen to glucose, fats/ amino acids are converted to glucose, and there is reduced oxidation of glucose until the normal level of blood sugar is attained. Deamination / excess amino acids are deaminated (removal) of amino acid group, the amino group is converted to ammonia which combines with carbon (iv) oxide to form urea that is excreted through the kidney, urea is excreted through the skin as sweat. (4 marks) Detoxification/ poisonous substances are converted to less harmful compounds. (1 mark) Thermoregulation/ maintenance of body temperature heat is generated (in the liver) by chemicals activities, the heat is distributed (3 marks) NH2 + H →NH3 2HH3 + Co2 →Co (NH2)2 + H2O Ammonia urea 27. K.C.S.E 2010 PP1 No.18 Give two reasons why animals have specialized organ for excretion as compared to plants (2 marks) Animal form waste products more rapidly than plants/ Produce more metabolic wastes Animals don’t reuse their waste while plants reuse some of their wastes; 28. K.C.S.E 2010 PP1 No.19 State the changes that occur in arterioles in the human skin during thermoregulation. (2 marks) When temperature is high they dilate; when low they constrict (Acc. Vasodilatation) 111
29. K.C.S.E 2010 PP2 No.6 In an experiment to investigate a certain physiological process, a boiling tube labeled A and a test tube labeled B were covered with cotton wool. The two tubes were simultaneously filled with hot water and fitted with thermometers. The experimental set-up was as in the diagrams below. The temperatures reading were taken at the start and after every two minutes for twenty minutes. The results were as shown in the table below. Time Boiling tube A Temperature (0C) (minutes) 60 Test tube B 59 60 0 57 54 2 55 50 4 53 46 6 52 43 8 51 40 10 49 37 12 35 14 48 47 33 16 32 18 46 30 20 112
(a)Using the same axes, draw graphs of temperature against time. (6 marks (bi) Work out the rate of heat in the boiling tube labeled A and test tube labeled B between the 5th and 15th minutes. A 56 - 48.5 = 7.5 = 0.75 + - 0.05 per minute. 15 – 5 10 B 48 - 34 = 14 = 1.4 + - 0.05 per minute. 15 - 5 10 ii) Account for the answers in (b) (i) above. (2 marks) B has a large surface area to volume ratio making it to lose heat to the surrounding faster; Acc the converse/ viceversa. iii) How does the explanation in (b) (ii) above apply to an elephant and a rat? (2 marks) A rat has a larger surface area to volume ratio compared to an elephant; making the rate to lose heat at a faster rate than an elephant; Acc: the converse/ Viceversa. C(i) State the role of the cotton wool in this experiment. (1 mark) Insulate against heat loss (to surrounding) ii) Name two structures in mammals that play the role stated in (c) (i) above (2 marks) Subcutaneous fat (layer) / Adipose tissue/ Bludder; fur/ hair; Rej: wool 113
(d) State three advantages of having constant body temperature in mammals. (3 marks) Are active always (even under very cold conditions); Able to escape from predators/ search for food/ mates (because they are active always) Can survive in (any habitat) both cold & hot habitat / wide range of habitats. 30. K.C.S.E 2011 PP1 No.1 Name two kidney diseases Nephritis Kidney stones 31. K.C.S.E 2011 PP1 No.25 State one economic importance of each of the following plant excretory products. (a) Tannin Softening of leather/ conversion or treatment of hides or skins to leather/ tanning leather/ (b) Quinine Treatment of malaria (c) Caffeine Stimulant in beverages/ increase mental activities/ reduce fatigue 32. K.C.S.E 2011 PP2 No.6 (b) Explain how osmotic pressure in the human blood is maintained at normal level. (5marks) When OP of blood increases (beyond normal) the osmoceptors in the hypothalamus detects this & stimulates the pituitary glands, to secrete more ADH/V asopresin, which makes kidney tubules more permeable to water, & more water is re-absorbed into the blood, reducing up to normal level. When the OP goes below normal, osmoreceptors in the hypothalamus detects this pituitary gland less stimulated, less ADH released, kidney tubules less permeable to water, less water reabsorbed into the blood rising up to normal level. 114
33. K.C.S.E 2011 PP2 No.7 (b) Explain how the human skin brings about cooling of the body on a hot day. (7marks) Erector pilli muscle relax, and hats lies flat, trapping less air, thus reducing insulation/more heat lost, blood capillaries/vessels/arterioles I n the skin vasodilator & more blood is brought near skin surface, increasing heat loss, by radiation/Convection Sweat glands release (more) sweat to the skin surface the sweat absorbs latent heat of vaporization from the body when it evaporates thus bringing a cooling effect. 34. K.C.S.E 2012 PP1 No.19 List four symptoms of diabetes mellitus. (4 marks) Passing urine frequently/ poly uria; Glucose in urine/ gylcocuria/ excess glucose in blood/ hyperglycemia: Reject glucose in blood/ alot of glucose alone; Reject sweet urine, Ace. sugarin urine; Reject sugary urine/ sugar particles in urine Constant feeling of thirst// frequent dehydration. Reject if constant/ frequent missing Loss of weight Excessive eating/ polyphagia/hyperphagia; Poor resistance to diseases; 35. K.C.S.E 2012 PP2 No.2 The diagram below illustrates the structure of the kidney nephron. (a) Name the part labeled E. Glomerulus; rej glomeruli 115
(b) How is the part labeled F adapted to its function? It is long to increase surface area for re-absorption of water; It is lined with a network of blood capillaries to enhance re-absorption of water; It is U- shaped to bring about a counter current multiplier effect/ to concentrate salts in the medulla to bring about re-absorption of water. (c) State three physiological mechanisms of controlling the human body temperature during a cold day. Vasoconstriction Hair rises Shivering: 36. KCSE 2013 PP 2 NO 8 Describe the role of the following organs in excretion and homeostasis. (a) The liver (10mks) Detoxification kipfer cells destroys foreign materials while catalase converts hydrogen peroxide (toxic) to harmless substances. Deamination - excess amino acids are not used up instead deaminated to urea and expel out through the kidney. Regulation of plasma proteins - Haemoglobin is broken down to haem and globin. Haem is used to form bile pigments i.e bilverdin and bilirubirin Thermoregulation; Its large size, high degree of metabolic reaction and excellent supply of bood produces heat and transport it to various tissues Regulation of blood sugar with influence of pancreatic hormones insulin and glusagon of excess glucose to glyoogen while giucagon stimulates conversion of glycogen to glucose Inactivation of hormones and drugs to inactive compounds by products are carried to the kidney and eliminated. (b) The skin during the hot environment conditions. (10mks) Bood vessels vasodilate increase more blood flow near the surface of the skin encouraging heat loss. The erector pili muscles in the skin relaxies; lowering the hair, no air is entrapped thus heat is dissipated to the environment, The sweat glands in the skin secretes sweat which evaporates leaving a cooling effect on the body, Metabolic rate in the skin decreases thus lowering heat production. 116
37. K.C.S.E 2014 PP 2 NO 8 (a)How does excretion take place in plants? (4 marks) Diffusion of carbon (IV) oxide and oxygen; through stomata / lenticels; deposition /some wastes are stored in tissues in non-toxic form (calcium oxalate, caffeine, nicotine quinine; some of these tissues /organs drop off from plants (leaves flowers fruits and bark) Some wastes are released by transpiration, stomata and lenticels (as water vapour) others are released by guttation; (through hydathodes as water) Others are released by exudation (eg salts, gum, calcium plate, resin water( wrong examples don't ward) (b)Describe the role of the human skin in homeostasis. (16 marks) When body temperature is lowered below normal blood vessels / blood arterials in the skin constrict; blood is diverted to a shunt system, accept less blood flows to the skin / less heat vessels lost when body temperature is When body temperature is lowered below normal Erector muscles contract; hair stands erect; more is trapped; air is a hard conductor and insulates the body against heat loss; when body temperature is raised above normal, erects, pelil muscles relax; hair lies on skin; less air is trapped; more heat is lost; When body temperature is lowered below normal, less fluids are absorbed by sweat glands / less sweating; less vaporization of water; when body temperature is raised above normal, sweat glands are stimulated more sweat is produced, sweat evaporates / water in the sweat evaporates and takes up heat from the body. Body is cooled / body temperature is lowered 117
FORM III 9. CLASSIFICATION Specific Objectives - Review of binomial nomenclature - General principles of classification - General characteristics of kingdoms Monera - Protoctista - Fungi - Plantae - Animalia - Main characteristics of major divisions of plantae - Bryophyta - Pteridophyta - Spermatophyta (cover only up to class level) - Main Characteristics of the Phyla Arthropoda and Chordata (cover up to classes as shown) - Arthropoda - diplopoda chilopoda - insecta - crustacean - arachnida - Chordata - Pisces - Amphibian - Reptilian - Ayes - mammalia - Construction and use of simple dichotomous keys based on observable features of plants and animals Practical activities - Examine live/preserved specimen or photographs of representatives of major divisions of plantae and phyla arthropoda and chordata - Construct simple dichotomous keys using leaves/parts of common plants/arthropods/ common chordates in the local environment - Use dichotomous keys to identify organisms By the end of the topic, the learner should be able to: a) state briefly the general principles of classification of living organisms b) state general characteristics of each of the five kingdoms c) state the main characteristics of arthropoda, chordata and major divisions of plantae d) name classes of spermatophyta 118
e) describe the main characteristics of classes of phyla arthropoda and chordata f) use observable external features to construct simple dichotomous keys of plants and animals g) use already constructed dichotomous keys to identify organisms. 119
1. K.C.S.E 1995 PP1 No.3 State two ways in which some fungi are harmful to man (2 marks) Food Spoilage Poisoning / cause disease 2. K.C.S.E 1995 PP1 No.6 The diagram below represents a fern Name (2 marks) (a)The parts labeled A and B A - Scrus – acc. Sori B- Rhizome (b) The division to which the plant belongs (1 mark) Pteridophyta 3. K.C.S.E 1996 PP1 No.5 An organism has an exoskeleton segmented body, two pairs of legs per segment, a pair of eyes and a pair short antennae belongs to the phylum (1 mark) Arthropoda 4. K.C.S.E 1996 PP1 No.6 What are two organisms considered to belong to the same species (2 marks) Capable of interbreeding; to produce viable offsprings 5. K.C.S.E 1997 PP1 No.2 A student caught an animal which had the following characteristics: Body divided into two parts Simple eyes Eight legs. Which class did the animal belong to? Arachnida 120
6. K.C.S.E 1998 PP1 No.16 A student placed a drop of pond water in a cavity slide and observed it under the microscope. The student observed many fast moving organisms, one of which is represented in the diagram below. (a)(i) Name the phylum to which the organism belongs Protozoa (ii) Give a reason for your answer in (a) (i) above Unicellular/ single celled (b)Name the structures labeled N, P and Q. N- Contractile vacuole P – Cilia, Acc cilium Q – Gullet/cytopharynx c) State two observable features that enable the organism to move fast. Cilia Streamlined body. 7. K.C.S.E 1999 PP1 No.10 Below is a list of organisms, which belong to classes Insecta, Myriapoda and Archnida: Tick, centipede, praying mantis, tsetse fly, millipede and spider. Place the organisms in their respective classes in the table below. Give reasons Classes Organisms Reasons Insecta Myriapoda Arachnida 121
Classes Organisms Reasons Insecta Praying Mantis 3 body parts Tsetse fly 3 pairs of legs Myriapoda Centipede Many segments Millipede Many legs Arachnida Tick 2 body parts Spider, 4 parts. Rej; if mixed Acc; if it is one and correct. 8. K.C.S.E 2001 PP1 No.1 Other than having many features in common, state the other characteristics of a species Interbreed to produce fertile/ viable offspring 9. K.C.S.E 2002 PP1 No.1 Besides the abdomen, name the other body part of members of Arachnida, Cephalothorax; 10. K.C.S.E 2003 PP1 No.2 Name the phylum whose members possess notochord Chordata 11. K.C.S.E 2004 PP1 No.8 Name the class in the phylum arthropoda which has the largest number of individuals? 1mark) Insecta; Rej insects/ exopoda 12. K.C.S.E 2005 PP1 No.5 To which class does an animal with two body parts and four Pairs of legs belong? (1mk) Arachnida 13. K.C.S.E 2006 PP1 No.6 (a) State three characteristics of Monera that are not found in other kingdoms. (3 marks) The genetic/ nuclear material is not surrounded by membrane. Smaller in size/ smallest. Lack most organelles/ few organelles/ lack nucleolus Mitochondria, Ribosome/chloroplast/ lysosomes Endoplasmic reticulum/ Golgi apparatus b) Name the class to which a termite belongs (1mark) Insecta 122
14. K.C.S.E 2007 PP1 No.1 (a) What is meant by the term binomial nomenclature (1 mark) Binomial nomenclature is a system of naming organisms by giving them two scientific names; the genetic and the specific names. (b) Give two reasons why classification is important (2 marks) It makes it easies to identify an organism It is easier to describe an organism as it is based on characteristics of the organism Large number of organisms is divided into smaller groups depending on characteristics The whole world uses the same groupings, so that everyone understands each other. 15. K.C.S.E 2008 PP1 No.25 Giving a reason in each case, name the class to which each of the following organisms 4 marks) (a) Bean plant - Dicotyledonae Reason - Leaves have net veined; two cotyledon; tap root system; xylem with phloem in between the arms (b) Bat - Flying mammal Reason - Have sweat glands; 3 ear ossicle; presence of fur; mammaring glands 16. K.C.S.E 2009 PP1 No.1 (a) Name the external feature which is common in birds, fish and reptiles (1 mark) Scales/ scale Reject Trail (2 marks) (b)State two characteristics of fungi Most have cell wall made up of cultic (or cellulose) Rej cellulose alone Most reproduce by means of spores/ sporulation They are eukanyotee/eukaryotic They are heterotrophy/ lack chloroplasts / some are saprophytic while others are Parasitic Have network of hyphae/ mycelia Store food in form of glycogen or oil droplets (both must be mentioned) 123
17. K.C.S.E 2010 PP1 No.8 State three external differences between chilopoda and diplopoda. (3 marks) Chilopoda Diplopoda A pair of (walking)legs per segment 2 pairs of(walking)legs per segment Body flattened dosoventrally Body cylindrical in shape Body divided into head and trunk Acc. Body divided into head thorax and Body divided into two body parts trunk Acc body divided into three Posterior genital aperture body parts Has poisonous claws Anterior genital aperture Have long antennae Lacks poisonous claws Have short antennae. 18. K.C.S.E 2010 PP1 No.12 The diagram below illustrates the structure of bread mould. (a)Name the part labeled J (1 mark) J – Sporangium (b)State the function of the structure labeled K (2 marks) Absorption of soluble substances/ digested food Secretion of digestive enzymes; Anchorage (of mould on substrate); anchorage must be in the right context 124
19. K.C.S.E 2010 PP1 No.29 The diagram below represents a female cone. (a)Name the subdivision of the plant from which the cone was obtained. (1 mark) Gymnospermae/ Gymnospermatophyta/ Gymnosperonaphyta; (b)Other than the presence of cones, name two other external features that identify plants in the subdivision named in (a) above. (2 marks) Needle-like leaves; thick waxy cuticle Naked seeds; sunken stomata. 20. K.C.S.E 2011 PP1 No.3 Give three reasons for classifying organisms. Identify similarities and differences between organisms; Organize scientific knowledge in an orderly system Monitor emergency presence and disappearance of organism in and from earth; Grouping organism for easy study 21. K.C.S.E 2011 PP1 No.8 State three characteristics of the class Crustacea Fused head and thorax/ capholothorax (often) protected by carapace. Gaseous exchange through gills Two pairs of antennae Five more pairs of limbs/ five to twenty pairs of limbs; rej five A pair of compound eyes Three pairs of mouth parts (consisting of labial pulps / maxillae) 125
22. K.C.S.E 2011 PP1 No.9 The diagrams below illustrate the organs of some flowering plants. State the classes of plants to which each belong. A – Dicotyledonae B – Monocotyledonae 23. K.C.S.E 2011 PP1 No.12 The diagram below represents a certain organism. State the phylum and class of carbohydrates in the human body. Pylum – Chordata Class – Aves 126
24. K.C.S.E 2012 PP1 No.2 The diagram below represents a certain organism collected by a student at the sea shore. (a) Name the class to which the organism belongs. Crustaceae/ Crustacea; (b)Give three reasons for your answer in (a) above. Head fused with thorax/ has cephalothorax; Have two parts of artermae Have compound eyes/ a pair of compound eyes; Have five two twenty pairs of limbs; Have external gills; 25. KCSE 2013 PPI NO 3(a) State two eternal features found in the class mammalia only. (2mks) Presence of mammary glands Presence of hairs or far in their skin (b)Name the taxonomic unit that comes immediately after a phylum in classification (1mk) Class 26. KCSE 2013 PPI NO 8 Construct a step in dichotomous key using two leaves one with serrated and other with smooth margin. (2mks) Leaf margin serrated.....................specimen X Leaf margin smooth ..................specimen Y 27. KCSE 2013 PP1 NO 12.(a) A student collected an organism and observed the following features: simple eyes, four pairs of legs and two body parts. (a)(i)State the class to which the organism belongs. (1mk) Arachnida 127
(ii)Give an example of an organism in this class. (1mk) Spider (b) Name the kingdom to which plasmodium belongs. (1mk) Protoctista 28. KCSE 2013 PPI NO 13 State two characteristics of living organisms that are specific to plants (2mks) Autotrophic in their mode of Nutrition Have a localized movement. 29. KCSE 2013 PP2 NO 1 (a) The diagram below represents a plant in division Bryophyta. o (2mks) (i)Name the parts labelled B and D oB Seta oD Rhizoid (ii)State one function for each of the parts labeled A and C. (2mks) oA Release spores oC Photosynthesis activity accept manufactures food for the plant 128
(b)The diagram below represents a member of the kingdom Animalia. (i)Name the pylem to which the organism belongs. (1mk) Arthropoda (ii) Using observable features in the diagram, give three reasons for the answer in b (i) (3mks) Presence of jointed walking legs The body is segmented Bilateral body symmetry. 30. KCSE 2015 PP1 NO 1 (1 mark) (a)What is meant by the term binomial nomenclature? (b) State two guidelines that should be followed when typing scientific names.(2 marks) 31. KCSE 2015 PP1 NO 16 State four structural differences between millipedes and centipedes. 4 marks) Millipedes Centipedes 129
10. ECOLOGY Specific Objectives - Concepts of Ecology - Ecology - Habitat - Niche - Population - Community Ecosystem - Biomass - Carrying capacity - Factors in an ecosystem - Abiotic factors (environmental factors) - light, temperature, atmospheric pressure, salinity, humidity, pH and wind - Biotic factors - Inter-relationships – competition, predation, saprophytism, parasitism and symbiosis - Nitrogen cycle - Energy flow in an ecosystem. Food chains, food webs, decomposers, pyramid of numbers and pyramid of biomass - Population estimation methods - Quadrat method - Line transect - Belt transect - Capture - recapture method - Adaptations of plants to various habitats - Xerophytes - Mesophytes (common terrestrial plants) - Hydrophytes - Nymphea, Salvinia, spp - Halophytes — mangrove - Effect of pollution on human beings and other organisms Causes, effects and control of pollutants in air, water and soil - Human diseases - Bacterial diseases - Cholera and Typhoid - Protozoa - Malaria and Amoebic dysentry (Amoebiasis) - Ascaris lumbricoides and Schistosoma - Mode of transmission - Effects of the parasites on the hosts - Adaptive characteristics of the parasites - Control/prevention of diseases associated with the parasites Practical activities - Collect, record, analyse and interpret data from ecological studies (examples of food chains should be used to join up to make food webs. Calculate ratios of consumers to producers from data provided) - Examine specimens of hydrophytes, mesophytes and xerophytes, and identify the features that adapt them to their habitats 130
- Examine roots of legumes taken from fertile and poor soils to compare the number of root nodules - Estimate populations using sampling methods (for quadrat and line/belt transect, measure pl-1, temperature, wind direction and humidity) By the end of the topic, the learner should be able to: a) define the terms ecology, habitat, biomass, ecosystem and carrying capacity b) identify the physical (abiotic) and biological (biotic) factors in a given ecosystem c) describe the inter relationships of organisms in the ecosystem d) differentiate between saprophytism, parasitism and symbiosis e) explain the importance of fungi and bacteria as decomposers f) relate the mode of transmission to prevention/control of named parasites g) describe the adaptive characteristics of named parasites to hosts h) explain the importance of symbiotic bacteria in leguminous plants i) describe the nitrogen cycle j) explain the flow of energy in the ecosystem k) identify and construct food chains and food webs, pyramid of numbers and pyramid of biomass i) explain the use of various methods of estimating population m) relate adaptations of plants to various habitats n) describe the effects of pollutants in air, water and soil on humans and other living organisms o) identify symptoms of different types of human diseases, methods of transmission and control. 131
1. K.C.S.E 1995 PP1 No.13 The chart below shows a feeding relationship in a certain ecosystem o (a)Construct two food chains ending with a tertiary consumer in each case (2 marks) Green plants → Grasshoppers → Lizards → snakes Green plants →Grasshoppers → Lizards → Cats Green plants →Mice →Snakes →Hawkers Green plants →Mice → Snakes → cats (b)Which organism has the largest variety of predators in the food web? (1 mark) Mice (c)Name secondary consumers in food web (2 marks) Lizards eat Hawk snakes, Rej. If any primary, tertiary consumer is given (d)Suggest three ways in which the ecosystem would be affected in there was a prolonged drought. Most plants will die dry (Some) organisms may starve to death (Some) organisms may migrate 2. K.C.S.E 1995 PP1 NO. 15 Describe how the quadrant method can be used to estimate the population of various species of plants in a given habitat (5 marks) Measure the total area of the habitat, throw or mark out the quardrat in the area for the study; at random. Identify label the various species of the plants in the quardrat; count plants of each species; record the numbers, repeat the process (owtte) work out the average per quardrat for each species in the area/ calculate the population for the total area in Nairobi. 132
3. K.C.S.E 1996 PP1 No.15 To estimate the population size of crabs in a certain lagoon, traps were laid at random. 400 crabs were caught, marked and released back into the lagoon. Four days later, traps were laid again and crabs were caught. Out of the 374 crabs, 80 were found to be marked. (a) Calculate the population size of the crabs in the lagoon using the formula below N= n x M m Where N = Total population of crabs in the lagoon n = Total number of crabs in the second catch M = Number of marked crabs during the first m= Number of marked crabs in the second catch (2 marks) o *Size=374 x 400 =1870 80 (b)State two assumptions that were made during the investigation (2 marks) There was even distribution of crabs No movement in and out of regions; no migration There was random distribution of errors after the first capture. (c)What is the name given to this method of estimating the population size? Capture/ recapture; capture release recapture. 4. K.C.S.E 1995 PP1 No.13 Oil can be applied on the stagnant water to control the spread of malaria. (a)How does this practice control the spread of malaria? Deprives the mosquito larvae of oxygen (b)Give a reason why this practice should be discouraged Water pollution 133
5. K.C.S.E 1997 PP1 No.11 The following below represents a feeding relationship in an ecosystem (a)Write down the food chains in which the guinea fowls are secondary consumers Grass → Grasshoppers → Guinea fowls Grass → Termites → Guinea fowls (b)What would be the short term effects on the ecosystem if lions invaded the area? Lions would compete with leopards for gazelles Gazelle numbers would reduce Grass would increase (c)Name the organism through which energy from the sun enters the food web. Grass; rej. Plants 6. K.C.S.E 1997 PP1 No.14 The diagram below represents a simplified nitrogen cycle. 134
(a)Name the organisms that cause process E and J E- Denitrifying bacteria; e.g pseudomonas denitrifications J- Nitrifying bacteria; Nitrobacteria reject nitrosamines (b)Name the process represented by F and H. H- Death decay/ decomposition; excretion/ Aminonification putrefaction egestion. F- Nitrogen fixation (c)Name the group of organism represented by G Plants 7. K.C.S.E 1997 PP1 No.19 (a) What is parasitism? An association between two organisms; where one benefits; and the other is adversely affected. Or an association where an organism lives in or on another living or organism: obtaining from it and causing harm without necessary killing it. (b) Describe how the tapeworm is adapted to a parasitic mode of life Lays many eggs for survival Have hooks to attach it in the small intestines It is adapted to respire under low oxygen concentration Eggs have a hard covering to resist the effect of digestive enzymes 8. K.C.S.E 1998 PP1 No.5 What is the relationship between leguminous plants and bacteria found in their root nodules. Symbiotic/ both benefit/ mutual benefit; correct description of mutual benefit 9. K.C.S.E 1998 PP1 No.10 Give two reasons why primary productivity in an aquatic ecosystem decreases with depth. Light intensity decreases with depth light limiting Temperature decreases with depth 10. K.C.S.E 1998 PP1 No.11 State two ways by which the human immuno deficiency (H.I.V) is transmitted other than through sexual intercourse? Use of unsterilized instrument; Blood transfusion with infected blood Mother to the foetus/ mother to baby infant/ breast milk/ sharing of instruments e.g needles syringes, razor blade e.t.c Mixing of infected blood through cuts 135
11. K.C.S.E 1998 PP1 No.15 The herbivorous mammalian species were introduced into an ecosystem at the same time and in equal numbers. The graph below represents their populations during the first seven years. Study the graph and answer the questions that follow. (a) (i) Which species has a better competitive ability? Species A; (ii) Give reason for your answer The rate of multiplication/ growth in A is faster than of species B (b)Account for the shape of the curve species A between (i) One year and three years 1-3 years plenty of resources more suitable environmental conditions/ such as food space e.t.c resource were not limiting hence the population increased exponentially rapidly; acc correctly named resource e.g food space. (ii)Three years and seven years 3-7 years shortage of resources/ limiting/ birth rate equals death rate; hence the population had become stagnant/ constant; acc; Environmental resistance has set in rej. Incorrect resources e.g PT and T. c) A natural predator for species A was introduced into the ecosystem. With a reason state how the population of each species would be affected. Species A would decrease (because of there is less competition with species A/ More resources available. 136
12. K.C.S.E 1999 PP1 No.5 Suggest three reasons why green plants are included in a fish aquarium. Provide shelter Provide food Provide oxygen Removal of CO2 breeding sites. 13. K.C.S.E 1999 PP1 No.13 a) Distinguish between a community and population. A community consists of all plants and animals (organisms of different species in a habitant interacting with each other. Population refers to the total number of a specific species at a particular time b) Describe how population of grasshoppers in a given area can be estimated. Use the capture and recapture methods; Catch the grasshoppers count and mark using permanent ink; record and release; and allow time 1 to 2 hours; recapture and count the marked and the unmarked; total population is equal to the number of marked and unmarked grasshoppers in the second sample multiplied by number marked grasshoppers in the first sample; divided by the number of grasshoppers marked in the second sample that were recaptured. 14. K.C.S.E 1999 PP1 No.17 Explain how the various activities of man have caused pollution of air. Sulphur based chemicals e.g. sulphure dioxide gas H2S Cl2 HCl2 produced by (food producing) industries /sewages matter, Affect gaseous exchange/makes acid rain /damages plants leaves. Acc. Pesticides, Herbicides, Insecticides, Acaricides, Aerosols. CFCs sprayed to control (plant) disease and pests, also affect respiratory organs of animals; the chemicals are residuals and persistent (not easily) broken down deplete. Ozone layers; smoke/fumes produced in areas with (heavy) industries and (high density of motor vehicles / fire which burn fuel/oils wood coal; These visibility; fumes also settle on leaves and stop photosynthesis (excessive) production of carbon dioxide causes the green house effect/Temp. inversion as a result of heating in lower layers of atmosphere; sound /noise produced incessantly b machines/ heavy vehicles/aircraft; affects hearing in animals; Dust, industrial production of (cement) generates dust; which finally settles on plants leaves limiting photosynthesis; removal of vegetation/cutting of trees; interferes with. 137
The carbon cycle; radioactive emissions; from nuclear reactors/mines/ x-rays machines bombs cause mutation/cancer/death. 15. K.C.S.E 2000 PP1 No.2 Give a reason why two species in ecosystems cannot occupy the same niche. Due to stiff competition of resources leading to elimination/ exclusion of one species; acc. currently named example food 16. K.C.S.E 2000 PP1 No.2 State two ways in which some fungi are beneficial to humans Some are source of food Some used in manufacture of medicine Some e.g. yeast used in alcoholic fermentation 17. K.C.S.E 2000 PP1 No.9 Explain how birds of prey are adapted to obtaining their food. Curved/ sharp/ hooked strong beaks fro killing / tearing/ ripping off flesh from bones Curved/ strong/ sharp claws for grabbing/ holding prey Sharp eyesight to spot prey from a distance 18. K.C.S.E 2000 PP1 No.16 The numbers of different types of animals supported by a square kilometer in two terrestrial ecosystems are shown in the table below Type of Type of animal Number of animals supported per ecosystem sq. km Acacia Domestic animals savannah Cattle 7 Goat 30 Sheep 10 Bush land Wild games 450 Thomsons’s gazelles Eland 20 Wildebeest 60 Domestic animals Cattle 2 Goats 15 Sheep 5 Wild game Thomson’s gazelles 200 Eland 12 Wildebeest 10 (ai) Which domestic animal is better adapted to both ecosystems? Goat 138
(ii) Give a reason why the animal named in (a) (i) above is better adapted to the two ecosystems. It is a grazer and a browser (b)Why are cattle and sheep fewer in the bush land than in the savannah? Insufficient grass in bush/ aren’t adapted to eating twigs/ not browsers/ are grazers (ci) Name suitable methods that were used to estimate the population of: Domestic animals - total counts Wild animals - total counts; aerial counts/ quadrat/ Belt transect/ capture/ recapture (ii) Give a reason why the method named for wild animals in (c) (i) above is suitable Analyzing gut counts, studying dentition/ breaks/ claws/ parts (d) State three methods which could be used to determine the diet of wild animals in an ecosystem Observation Examine droppings Dissecting a sample of animals/ study structure/ nature of digestive System/ size of caecum/ length of intestine/ chamber (e)Name four biotic factors that could have regulated the animal population in both ecosystems Irrigation Competition; diseases Predation; human activity/ man accept any correct Parasitism (f)State four human activities that affect population of animals in game parks Poaching, Cropping, Culling, Licensed spot hunting Pollution; translocation Burning trees, charcoal- deforestation 139
19. K.C.S.E 2000 PP1 No.18 How are leaves of mesophytes suited to their functions? Broad/ wide/ flat lamina provides large surface area for absorption of (O) and sunlight, thin to ensure short distance of CO2 reach photosynthesis/ palisade cells; presence of stomata guard cells for efficient diffusion of O2 gaseous exchange / H2O vapour transpiration/ CO2 into the leaf transparent cuticle epidermal cells; for light penetration into palisade cell which contains chloroplast next to upper epidermis; these receives maximum light for photosynthesis. Chloroplasts have chlorophyll, which traps light energy. Leaves have vein, xylem and phloem to transport products of photosynthesis to other part of the plant. Air spaces on spongy mesopyll, easily circulates gases/ CO2 diffuse into palisade cells. Mosaic arrangements of leaves; enable leaves to trap sunlight. 20. K.C.S.E 2001 PP1 No.2 Why are green plants referred to as primary producers in an ecosystem? Utilize energy from the sun to manufacture food/ photosynthesis; for subsequent tropic level/ consumers/ other organisms 21. K.C.S.E 2001 PP1 No.13 The diagram below represents the nitrogen cycle (a) State the process labeled A – Nitrogen fixation D – Absorption (b) Name the compound represented by B Nitrite/ nitrites/ NO-2 140
(c) Name the group of organisms labeled C Leguminous plants, (acc. Legume/ acc examples e.g. beans peas) (d) (i) name the group of plants which promote process A Symbiotic bacteria (ii) State the part of the plant where process A takes place Roots nodules; rej root or nodules alone (e) How would excess pesticides in the soil interfere with process A Killing / reducing of decomposers Killing/reduction of nitrogen fixing bacteria/ nitrogen fixing microorganisms Destruction of leguminous plants 22. K.C.S.E 2002 PP1 No.2 (a) Name the bacteria found in the root nodules of leguminous plant Rhizobium Nitrogen fixing bacteria (b)State the association of the bacteria named in (a) above with the leguminous plants. Symbiosis / mutualism 23. K.C.S.E 2002 PP1 No.7 Explain why the carrying capacity of wild animals is higher than that for cattle in a given piece of land Cattle are mainly grazers while others are browser. 24. K.C.S.E 2002 PP1 No.16 Ascaris lumbricoides in an example for an endo – parasite a) The name Ascaris refers to Genus b) State the habitat of the organism Ileum/ colon/ duodenum/ intestines/ of humans or intestines of Ileum/ colon/ duodenum/ intestines/ of humans or intestines of pig c)State three ways in which the organism is adapted to living in its habitat. Lack of elaborate alimentary canal (simple guts) can tolerate raw corn Thick cuticle pellicle, reject the outer covering lays many eggs Mouthparts for sucking partly digested food 25. K.C.S.E 2003 PP1 No.5 a) Name the bacteria found in root nodules of leguminous plants. Rhizobium 141
b) What is the role of the bacteria named in (a) above? Convert nitrogen into nitrates / convert nitrogen into proteins / convert N2 into nitrogenous Compounds / fix N2 into nitrates. 26. K.C.S.E 2003 PP1 No.10 How are leaves of submerged adapted plants for photosynthesis? Numerous chloroplasts to absorb light / epidermis have chloroplasts to absorb light. Deeply divided / dissected leaves / branched leaves to increase surface area. Large air spaces for storage of air / buoyancy; acc parenchyma tissue for storage of air Have no cuticle to facilitate exchange of gases 27. K.C.S.E 2003 PP1 No.11 Name the causative agent of typhoid. Salmonella typhi; Acc.Bacteria / salmonella alone (must be underlined separately) 28. K.C.S.E 2003 PP1 No.16 a) What is meant by; i) Autecology Study of a single species within a community / ecosystem / habitat / environment. ii) Synecology Study of natural communities within an ecosystem b) The number and distribution of stomata on three different leaves are shown in the table below: Leaf Number of stomata Lower epidermis Upper epidermis 0 A 300 200 B 150 13 C 02 Suggest the possible habitat of the plants from which the leaves were obtained Leaf Habitat A aquatic / fresh water B Forest; Terrestrial C Arid / semi arid; desert. 142
(c)State the modifications found in the stomata of leaf C. Sunken Hairy Reserved rhythm Small stomatal pore 29. K.C.S.E 2004 PP1 No.3 How is aerenchyma tissue adapted to its function (2mks) Has air spaces; which store gases for gaseous exchange buoyancy; Acc. Floating. 30. K.C.S.E 2004 PP1 No.19 Explain how abiotic factors affect plants (20mks) Wind. In windy conditions the rate of transpiration increases; wind disperses fruits/ seeds; is an agent of pollination; acc. Spores for seed. Temperature Changes in temperatures affect the rate of photosynthesis and other biochemical reactions/ metabolic reactions/ enzymatic reactions/ enzymatic reactions, temperature increases rate of transpiration; Lights Plants need light for photosynthesis, some plants need light for flowering/ photoperiodism/ seeds like lettuce require light for germination. Humidity When humidity is low, the rate of transpiration increases; PH Each plant requires a specific pH to grow well/ acidic/ alkalinity/ neutral; Salinity Plants with salt tolerant tissues grow in saline area; plants in estuaries adjust to salt fluctuations; Topography North facing slopes in temperature lands have more plants than south facing slope. Plants on windward side have stunted/ distorted growth; Acc. Comparisons of mountains and valleys. Acc. Description of other areas with other topographies e.g. River valley rainfall/ water Fewer plants in areas/ semi arid and water is needed for germination/ is a raw material for photosynthesis/ dissolves/ minerals salts/ provides turgidity for support/ fruits/ seeds 143
Pressure; Variation in atmospheric pressure affect availability of CO+2+ which affects photosynthesis and low pressure increase rate of transpiration; and affect amount of oxygen; for respiration Mineral salts/ trace elements Affects distribution of plants in the soils Plants thrive well where there are mineral salts in the soil. Plants living in the soil deficient in particular mineral element has special methods obtaining it; for example legumes obtaining from nitrogen by fixation or carnivorous. 31. K.C.S.E 2005 PP1 No.10 (1mks) Name the organism that causes amoebic dysentery. Entamoeba hystolystica 32. K.C.S.E 2005 PP1 No.17 After an ecological study of feeding relationships students constructed the food web below. (a) Name the process through which energy from the sun is incorporated into the food web. (1 mark) Photosynthesis (b) State the mode of feeding of the birds in the food web.(1 mark) Heterotrophism - holozoic (c) Name two ecosystems in which the organisms in the food web live. (2 marks) Pond or dam, rain forests. (d) Prom the information in the food web; construct a food chain with the large bird as a quaternary consumer. (I mark) Algae —► Zoo plankton —> small fish —► birds —» large bird. 144
(e) What would happen to the organisms in the food web if bird N migrated? (3 marks) Snails would increase in number Bird M would increase in number. Green plants would decrease in number (f) Not all the energy from one trophic level is available to the next level. Explain. (3 marks) The energy to be passed on from one trophic level to the next is contained in food materials. Most of the food taken in by consumers passes through the digestive track as undigested matter that is removed as faeces. The digested materials are absorbed in to the bloodstream and conveyed to various tissues of the body. Most of the absorbed food materials are used in respiration, to produce energy. Some is lost as heat during sweating, evaporation and transpiration in plants. Not all energy is trapped and passed on to the next level or not all organisms are consumed to give energy. (g) (i)Two organisms which play a role in the ecosystems are not included in the food web. Name them. (2 marks) Scavengers e.g. vultures Decomposers e.g. saprophytic bacteria and fungi (ii) - Scavengers feed on dead bodies of herbivores and carnivore/the consumers. Decomposers act upon the remains of the producers and consumers causing decay hence release inorganic materials or nutrients, which are later re-used by producers to make new organic compounds, i.e. they bring about recycling of materials/nutrients in an ecosystem. (ii) State the role played by the organisms named in g(i) above. (1 mark) Scavengers feed on dead bodies of herbivores and carnivore/the consumers. Decomposers act upon the remains of the producers and consumers causing decay hence release inorganic materials or nutrients, which are later re-used by producers to make new organic compounds, i.e. they bring about recycling of materials/nutrients in an ecosystem. (h) (i) State three human activities that would affect the ecosystems. (3 marks) Deforestation,- Overgrazing, - Hunting, poaching, over fishing Poor waste disposal / Environmental pollution 145
(ii) Explain how the activities stated in h(i) above would affect the ecosystems.(3 marks) Deforestation - lack of trees leads to reduced number of producers a ecosystem. Overgrazing - many animals eat away and trample the vegetatioi o reducing/depleting the number of producers. - Lead to gully erosion hence carrying away some of tic underground and crawling animals (consumers Hunting/poaching/over fishing - This will lower the number of certain species of animals disrupting ecological balance. Poor waste disposal/environmental pollution - leads to eutrophication o hence death of water plants and animals. 33. K.C.S.E 2006 PP1 No.16 (2mks) What is the importance of the following in an ecosystem? Decomposers - recycling of nutrients Predation - regulation of numbers/ population 34. K.C.S.E 2006 PP1 No.26 The chart below represents a simplified nitrogen cycle. What is represented by X, Y, and Z? X- Denitrifying bacteria/ denitrification Y- Animals/ Herbivores; accept primary consumers Z- Nitrogen fixing bacteria (in soil) accept Azotobacter. 146
35. K.C.S.E 2006 PP2 No.3 a) Distinguish between pyramid of numbers and pyramid of biomass. (2mks) Pyramid of numbers is a diagrammatic representation of the number of organism, at each trophic level in a food chain; while biomass is a diagrammatic representation of dry weight organism at each trophic level in a food chain b) Give three reasons for loss of energy from one trophic level to another in the food chain. (3mks) Insufficient utilization of food resource/ wastage Through respiration Though excretion c) Describe how the belt transects can be used in estimating the population of a shrub in grassland. Run two ropes parallel to each other a metre apart. Make points / stations along the belt. Count shrubs between two ropes at marked points along the whole belt and record. Repeat the process severally ( at least 3 times) and obtain the average. Calculate the area of belt transect, then the population for whole area As population = Total area × count per belt Belt area 36. K.C.S.E 2007 PP1 No.15 (a) Distinguish between population and community ( 2 marks) Population – It is all members of a given species in particular habitat at a particular time. Community- all organisms belonging to different species interact in the same habitat. (b) Name a method that could be used to estimate the population size of the following organisms (i) Fish in a pond (1 mark) Capture and recapture method (ii) Black jack in a garden (1mark) Line transect 37. K.C.S.E 2007 PP1 No.16 State two ways in which schistosoma species is adapted to parasitic mode of life (2 marks) Produce large number of eggs for increased survival Produce enzymes to digest human skin when penetrating Can withstand low oxygen concentration Have hooks – like structures to attach to the intestinal walls 147
38. K.C.S.E 2007 PP1 No.26 State one way by which HIV/AIDS is transmitted from mother to child (1 mark) During birth breast feeding 39. K.C.S.E 2007 PP2 No.8 Describe causes and methods of controlling water pollution (20 marks) It is addition of substance into water that may cause harm to organisms and are disruptive to ecosystem. The causes of water pollution include: Industrial effluents that may be toxic chemicals which may kill the aquatic organisms. It can be controlled by treating the effluents before discharging them. Hot water that reduces concentration of oxygen killing the animals. It is controlled by placing high penalties on factories discharging hot water. Oil spillage from oil tankers that reduces oxygen in water, penetration of light intensity and clog feathers of marine birds. It can be controlled by regular servicing of oil tankers. Domestic effluents that include: Untreated sewerage that causes water borne diseases. It can be controlled by treating sewerage before being discharged. Detergents that cause eutrophication causing reduced oxygen concentration. It is controlled by banning phosphate based detergents. Agricultural effluents that include: Pesticides and herbicides that have heavy metals that they may cumulates along the food chain killing the higher animals. It is controlled by use of biological control of pests. Inorganic fertilizers that have nitrates and sulphates that cause eutrophication is controlled by use of organic fertilizers. Silting due to soil erosion reduces penetration of light to the plants and clog respiratory surfaces of animals. It is controlled by proper methods of soil erosion and proper farming methods. 40. K.C.S.E 2008 PP1 No.14 Describe the three characteristics of a population (3 marks) Growth – increase/ decrease in numbers/ change in numbers Dispersion – Spread/ distribution of organisms in a habitat Density – Number of individual per unit area 148
41. K.C.S.E 2008 PP1 No.22 State two characteristics of aerenchyma tissue (1 mark) Large airspace Thin cell walls 42. K.C.S.E 2008 PP2 No.7 (20 marks) Describe the nitrogen cycle During thunderstorm/ lightning; nitrogen gas combines with O2 to form nitrogen oxides; nitrogen oxides dissolve in water to for nitric acid; acid is deposited in the soil by rain, nitric acid combines with chemical substance to form nitrates/ nitric acids dissolves to form nitrates which are absorbed by plants symbiotic bacteria/ such as rhizobium; which are found in root nodules of leguminous plants, fix free nitrogen to nitrates. Free living bacteria/ clatridium/ azotobacteria fix nitrogen to all rates Nostoc algae/ chlorella/ anaemia/ ix nitrogen to nitrates. Plants use Nitrates to form plant proteins Animals feed on plants and convert plant proteins into animal proteins Plants/ animals die and decomposed by bacteria/ saprophytes/ fungi decomposing plants/ animals/ release ammonia which is covered to nitrates/ by nitrosomomes nitrococcus bacteria Nitrates are converted to nitrates; by nitrobacteria Nitrates in the soil can be converted to free nitrogen/ denitrification by some fungi; pseudomonas/ hulobacillus denitrifying bacteria. 149
43. K.C.S.E 2009 PP1 No.2 Name two benefits that a parasite derives from the host (2 marks) Obtains food/ nutrients/ (Acc Habitat Shelter Rej protection) 44. K.C.S.E 2009 PP1 No.9 (a)Name the causative agents of the following diseases in humans (2 marks) Typhoid - Salmonella typhi; Amoebic dysentery- Entamoeba hystolytica (b) Name the disease in humans caused by plasmodium falciparum (1 mark) Malaria 45. K.C.S.E 2009 PP1 No.19 (a) State three effects of dumping untreated sewage into a river (3 mks) Leads to eutrophication; causes water bone disease Kill organisms in water;/ reduce amount of oxygen in the water/ reduce the quality of water for consuming change water PH; interferes with food charus/ trophic levels. (b) Name one process that is responsible for loss of energy from one trophic level to the next (1 mark) Respiration/ defecation/ excretion 46. K.C.S.E 2009 PP1 No.20 Other than using the quadrant, give two methods of estimating population of grass (2 marks) Belt transect Line transects 47. K.C.S.E 2009 PP1 No.25 State two ways in which parenchyma tissues in aquatic plants are adapted to their function (2 marks) Thin walled for easy diffusion of gases/ store a lot of air Have large air spaces which store air for buoyancy/ for gaseous exchange 48. (K.C.S.E 2009 PP2 No.3 a) What is meant by the term biological control ( 1 mark) Using a living organism to regulate/control/ reduce/ check the population of another organism 150
Search
Read the Text Version
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 24
- 25
- 26
- 27
- 28
- 29
- 30
- 31
- 32
- 33
- 34
- 35
- 36
- 37
- 38
- 39
- 40
- 41
- 42
- 43
- 44
- 45
- 46
- 47
- 48
- 49
- 50
- 51
- 52
- 53
- 54
- 55
- 56
- 57
- 58
- 59
- 60
- 61
- 62
- 63
- 64
- 65
- 66
- 67
- 68
- 69
- 70
- 71
- 72
- 73
- 74
- 75
- 76
- 77
- 78
- 79
- 80
- 81
- 82
- 83
- 84
- 85
- 86
- 87
- 88
- 89
- 90
- 91
- 92
- 93
- 94
- 95
- 96
- 97
- 98
- 99
- 100
- 101
- 102
- 103
- 104
- 105
- 106
- 107
- 108
- 109
- 110
- 111
- 112
- 113
- 114
- 115
- 116
- 117
- 118
- 119
- 120
- 121
- 122
- 123
- 124
- 125
- 126
- 127
- 128
- 129
- 130
- 131
- 132
- 133
- 134
- 135
- 136
- 137
- 138
- 139
- 140
- 141
- 142
- 143
- 144
- 145
- 146
- 147
- 148
- 149
- 150
- 151
- 152
- 153
- 154
- 155
- 156
- 157
- 158
- 159
- 160
- 161
- 162
- 163
- 164
- 165
- 166
- 167
- 168
- 169
- 170
- 171
- 172
- 173
- 174
- 175
- 176
- 177
- 178
- 179
- 180
- 181
- 182
- 183
- 184
- 185
- 186
- 187
- 188
- 189
- 190
- 191
- 192
- 193
- 194
- 195
- 196
- 197
- 198
- 199
- 200
- 201
- 202
- 203
- 204
- 205
- 206
- 207
- 208
- 209
- 210
- 211
- 212
- 213
- 214
- 215
- 216
- 217
- 218
- 219
- 220
- 221
- 222
- 223
- 224
- 225
- 226
- 227
- 228
- 229
- 230
- 231
- 232
- 233
- 234
- 235
- 236
- 237
- 238
- 239
- 240
- 241
- 242
- 243
- 244
- 245
- 246
- 247
- 248
- 249
- 250
- 251
- 252
- 253
- 254
- 255
- 256
- 257
- 258
- 259
- 260
- 261
- 262
- 263
- 264
- 265
- 266