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WESTLANDS FORM FOUR COMMON EVALUATION Kenya Certificate of Secondly Education BIOLOGY - Paper - 23171 July/August 2013 MARKING SCHEME 1. 2. 3. -Plasmolysis is a condition when a plant cell loses water and shrinks / becomes flaccid; while haemolysis occurs when a red blood cell absorbs water and bursts; Rej - Animal cell for rbc - a) Unicellular; b) Have a closed circulatory system: Accept 1st one - use lungs for gaseous exchange; - Are homoiothermic / endothermic; -3.) A parasite lives in or on its host organisms to obtain nutrients without killing it; while a predator kills its prey and feeds on it to obtain nutrients; b)- Breaks down organic matter to release nutrients into the ecosystem / enables nutrients cycling; Releases carbon (IV) oxide into the atmosphere for use by plants for photosynthesis; 4. a) i) - Humerus; ii) - has head / presence of trochlea / tuberosity; b) A-Articulates with glenoid cavity of scapula to form ball and socket joint; B - articulates with olecranon proces^of ulna to form a hinge joint; 5„- They are numerous / form a dense network around alveoli to create a steel concentration gradient for faster diffusion of gases; They have moist lining to dissolve gases so that they can diffuse faster in solution form; They have thin elastic muscular walls to reduce distances for faster diffusion of gases; 6. a) Hand lens; b) Microscope; 7. a) Co-enzymes are substances that enhance / promote activity of enzymes; b)- They are insoluble in water hence cannot easily be taken to respiring sites; - They require a lot of oxygen for complete metabolic breakdown to release energy; 5. a) Granum; Rej Grana b) Carbon (IV) oxide + hydrogen ions -» sugars + «t ,•«tnr » 9. a) The biomass is constant; and is independent on amount of fluids in the organism/ does not decrease due to loss of fluids. b) - Pyramid of numbers; - food chains; - food web; 10. -Organic matter in sewage is broken down by decomposers to release nutrients that cause rapid growth of water plants hence reduce primary production; Toxic / poisonous compounds in raw sewage kill microorganisms in the water; NB: Must mention toxic compounds in sewage Saprophytic fungi and bacteria in sewage utilize oxygen in decomposition organic matter thus decreasing available oxygen hence organisms die by suffocation; 11. a)Inner membrane is highly folded (Rej: Highly coiled) to form Cristae that increase surface area for attachment of respiratory en2ymes; (Rej: cristae are folded) has fluid filled matrix that has enzymes that take part in respiration; b)- Oxygen concentration; substrate concentration; surface area to body volume ratio; effect of hormones that affect respiration - Thyroxine; - Adrenaline; 12. a) i) - Telophase I / Telophase of meiosis I; ii) - Prophase I / Prophase of meiosis I; b) - Form spindle fibres during cell division; - Form cilia and flagella used in locomotion in unicellular organisms; ' 13. a) Rhizobiumsno/Rhizobium leeuminerosum; b) Symbiosis / symbiotic relationship; c) Fix nitrogen into the plant; 14. a) Has a large number of Sertoli cells that nourish developing spermatozoa; has seminiferous tubules that synthesize spermatozoa; More sweat is produced over the skin surface, evaporation of water in sweat lowers body ^ close tocoiled the skin surface dilate causing - Blood Has a capillaries long and highly epididymis that increase asurface biggerarea volume of blood to flow close to the skin for storage of spermatozoa; resulting in loss of body heat by radiation / convection b) Has placenta; which produces oestrogen and progesterone across the body surface; hormones for maintaining Hair lies flat over the skinpregnancy; surface due to relaxation of erector (pilli) muscle to reduce volume of air over the 15. a) To demonstrate phototropism in plants; skin surface hence more heat is lost by radiation / b) In A = The shoot grows and bends- towards the . convection; direction or light; 3 ~ Theorganisms shoot grows upright ancestry without to bending; 19. 1c -Enables of common develop c) The aluminium foil reflects light away hence auxins are structures that adapt them to different ecological niches evenly distributed in ae shoot that results is upright / occupy different habitatats; gro'V-h; 20. a)i) A plumule sheath / coleoptile; 16. a) growth in !increase ii) CPrimary = root hairs ; rej :results Hair roots roots. ±n height / length of the stem; while secondary growth results in b) Protects increase plumule; in thickness / girth / diameter of the stem; - b) Increased metabolic rate / increased break down of glucose; Increased ventilation (breathing) rate; increased heart beats / increased circulation rate; 22. a)-Causes kidney tuouies to become permeable to water; hence more water is reabsorbed back into the bleed stream; a)- Conduction of nervous impulses; Plays an important roie in osmoregulation; / ic-ak balance 23, a) Guard cell; I b) Conircb opening and closing of stomata; Has chlorcplasts that absorb sunlight for photosynthesis; b) The juvenile in hormone development larval 21. a) Located central promotes nervous system / CNS of / Spinal characteristics / inhibits / delays in an cord; Acc: In grey matter of spinal metamorphosis cord / brain / CNS. insect; while moulting hormone (ecdysone) promotes moulting / metamorphosis / development of larva to adult form; c) 18. a) Hypothalamus; Rej: ABA 24. a) Fungi; b) i) Fart X - sporangium; ii) Part Y - Rhizoids; 17. a) Blood group AB and blood group B; NB: both must be mentioned. b) The antibodies in anti-B serum reacted with antigen B in the blood groups; causing agglutination ; Abscisic acid; c) Most reproduce asexually while others sexually; 25. a) i) Genetic engineering refers to identification and alteration of a gene with desirable characteristics; and transferring to another organism in order to produce desirable products; ii) Co-dominance is a condition in organisms where both alleles express themselves equally / none is dorminant or recessive over the other; b) Either all offsprings will show dorminant characteristics; OR Half will show dominant while half will show recessive characteristics; temperature; pareafe.il . -.r -| ^ WESTLANDS FORM FOUR COMMON EVALUATION Kenya Certificate of Secondary Education BIOLOGY - Paper - 231/2 July/August 2013 MARKING SCHEME La) The gene for foot deforming being dominant; expresses itself in both homozygous and • heterozygous condition; girdle is hard to support the upper part of the body; The illium provide a large surface area for attachment of thigh muscles that move the legs; a)- Afferent arteriole wider than efferent arteriole creating high pressure; dense network of blood capillaries in the glomerulus create high pressure (since the lumen of capillaries is narrow); high pressure ofblood from the renal artery entering the glomerulus; b) It enhances the process of reabsorption of water. c) Excess amino acids are deaminated; where the amino group is reacted with hydrogen to form ammonia; Ammonia' is toxic and combines with carbon(IV) oxide to form less toxic urea; urea is then excreted in urine through the kidney; 4. a) Population density; Population growth; Population dispersion; acc first 2 2 deformity : 2 normal 1 deformity : i normal Use of Punnet square Parental genotype Dd x dd; etes^ :; T ......! ^gamete§’-— J! :.l0 |d; Cr d i d j Dd [ Dd _ | dd; L . | dd; | b) 1 Grasshopper. = 12 ; = 4 grasshoppers / m2; 3 Phenotypic ratio 2 deformity : 2 normal; OR 1 deformity : 1 normal; b) The individuals are readily selected against by natural selection; 2. a) Scapula ; Acc Scapular b) i) Humerus; in 600m2 = 600 x 4 = 2400 grasshoppers. c) Transect / line transect / belt transect/ capture recapture (acc the first) 5. a) X - rods; Y- cones; b) Has pigmented cells / melanin; to absorb stray light thus preventing internal reflection; c) Has photochemical pigment called iodopsin; It’s broken down (by bright light) into opsin and iodine; causing depolarization of their surface membrane; generating an impulse ii) Ball and socketjoin; c) Area = 30m x 120m = 600m2 Attachment of muscles. d) Has acetabulum depression / socket (on the side of ileum); which articulates with the head of femur to form ball and socket joint at the hip; have a hole obturator foramen covered by a tough inflexible connective tissues; to reduce the weight of the pelvic girdle (thereby reducing the load supported by the hindlimb); the aperture in obturator foreman allow for passage of blood vessels and nerves to the legs; pubic symphysis is made of flexible cartilage, to permit widening of female girdle during birth; pelvic