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Bondo Biology ppr 3 marking scheme

BONDO SUB-COUNTY SECONDARY SCHOOLS JOINT EVALUATION TEST – 2015

231/3

BIOLOGY

Paper 3

July/August- 2015

MARKING SCHEME

1.         (i)         –           Tissue in L1 should be shorter tham 3cm

                        –           Tissue in L2 should be longer than 3cm

                        –           tissue intest tube F (blank) should be 3cm. (3mks)

(ii)        L1 is hypertonic  to the cell sap of potato tissue; and therefore water moves out of the cells into L1 by osmosis; the cells become plasmolysed and flaccid and thus leads ro shrinking and decrease in length of the potato tissue;

E          L2 is hypotonic to the cell sap of the potato tissue cells; the cells therefore gain water by osmosis; and become turgid leading to increase in length of the tissue; (3mks)

            (iii)       It acted as a control experiment (1mk)

            (iv)      

Food substance Procedure Observation Conclusion
Starch To cm3 of the food substance in a test tube add 2 drops of iodine solution and shake; Blue back colour seen Starch is present
Reducing Sugar To 2cm3 of the food substance in a test tube, add 2cm3 of Benedict’s solution, Heat to boil; Colour changes from blue to green, to yellow, Orange or brown; Reducing sugar present

                                                                                                                                    (6mks)

2.         (a)        (i)        

Specimen Food Reason
A Aquatic matter and small invertebrates Wide shovel shaped beak
B Nectar Long, thin beak
C Nuts Short, thick strong beak
F Flesh Strong sharp curved talons /claws

                                                                                                                                       (4mks)

                        (ii)       

Part Habitat Reason
D Aquatic Webbed feet for  swimming / wadding 
E Tree branches Long feet / toes for grasping / perching

                                                                                                                                      (4mks)

            (b)        (i)         Divergent evolution;

                                    Reason: Similar basic structure and embryonic origin but modified into different

forms / appearance; (2mks)

                        (ii)        Enable the organisms / animals to utilize different ecological niches; to avoid

competition for food;  (2mks)                                                            

3.         Q – Self dispersal;ü

                        Reason – Dihisent / line of weakness for opening;ü

            R – Wind dispersal;ü

                        Reason – Presence of the parachute for floating in air;ü

S – Animal dispersal;ü

            Reason – The fruit is succulent / Juicy;ü

                                                                                                                                    (6mks)

(b)        Q- Marginal Placentation;

            S-Parietal placentation;

            T – Basal Placentation;

            U – Axile Placentation;                                                                                   (4mks)

(c)        Berry;

            Reason – has got fleshy / succulent mesocarp; (2mks)

                                                                                                                                    (2mks)