Biology Paper 3 Form 3 End Term 2 Exams 2021 with Marking Schemes
Answer all the questions in the spaces provided.
- You are provided with chemical reagents Q (Iodine solution), R (NaOH), S (CuSO4), T (DCPIP)and food solution X
Using the reagents provided carry out food test on solution X- Record your results in the table below. (12marks)
Food Substance Procedure Observation Conclusion - Suggest the importance of food substance present in solution X in a human body. (2mks)
- Record your results in the table below. (12marks)
- Below is a photograph of a certain animal. Examine it and answer the questions that follow.
- Giving a reason in each case, classify the animal into the taxonomic units in the table below. (4 marks)
Taxonomic unit Name of taxonomic unit Feature Phylum Class - Study the photograph shown below part of animal above.
List adaptive characteristics of part labeled G to its function. (4mks) - The following illustration shows a flow in the photograph shown above.
- Indicate on the illustration the direction of blood and water flow. (1mk)
- Name the type of flow represented in the illustration (1mk)
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- Name the process by which oxygen leaves water into capillaries of filaments. (1mk)
- What condition enables an efficient exchange of oxygen by process identified in d(i) above. (1mk)
- The atmospheric air has more oxygen than that dissolved in water yet a fish dies immediately after being withdrawn from water. Explain. (1mk)
- Giving a reason in each case, classify the animal into the taxonomic units in the table below. (4 marks)
- Study the photographs of plant structures shown below then answer the questions.
- For each type of structure shown above state a dispersal agent (4marks)
Structure Dispersal agent X1 X2 X3 X4 - Name the observable adaptive features in X1 and X2 that enable them to be dispersed by the dispersal agent identified. (2marks)
Structure Adaptive features X1 X2 -
- Give possible description of leaves and roots of plant of flower labeled R2.
Roots………………………………………………………………………….(2mks)
Leaves ……………………………………………………………………..(3mks) - Flower R2 has polypetalous characteristic. Explain. (1mk)
- Name part labeled Q on X3. (1mk)
- Give possible description of leaves and roots of plant of flower labeled R2.
- For each type of structure shown above state a dispersal agent (4marks)
Marking Scheme
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- (12marks)
Food substance
Procedure
Observation
Conclusion
starch
Add 3 drops of iodine solution
Solution turns blue black
Starch present
protein
Add drops of NaOH
Add drops of CuSO4
Solution turns purple
Protein present
Ascorbic acid/ Vitamin C
Into about 2cm3 of DCPIP add drops of food solution X
Blue colour of DCPIP persists
Ascorbic acid absent
- – body building food
- Energy giving food
- (12marks)
-
- Giving a reason in each case, classify the animal into the taxonomic units in the table below. (4 marks)
Taxonomic unit Name of taxonomic unit Feature Phylum Chordata Presence of a notochord at a stage of embryo development Class Pisces Presence of fins; presence of lateral line;
Presence of gills -
- Have moist surfaces to dissolve oxygen gas
- Have a thin epithelial lining for gases to move through a short distance
- Have a large capillary network for maximum gaseous exchange
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- answer on figure
- Counter current flow.
-
- Diffusion.
- A steep concentration gradient of oxygen gas.
- While in water filaments part and creates a large surface area for gaseous exchange.
When a fish is removed out of water into air, filaments sticks together reduces surface area for gaseous exchange fish suffocates and dies.
- Giving a reason in each case, classify the animal into the taxonomic units in the table below. (4 marks)
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-
Structure Dispersal agent X1 Wind X2 Water X3 Explosive mechanism X4 Animal -
Structure Adaptive features X1 Has wing like structures that enable it to float in wind X2 Mesocarp fibrous and spongy to trap air;
Air trapped make fruit light and buoyant to float on water. -
- Root system of R2 - Tap root; star shaped xylem vessel
Leaf characteristics of R2 – Network venation; presence of petiole; - Polypetalous characteristic; petals are free/petals are not fused
- Funicle
- Root system of R2 - Tap root; star shaped xylem vessel
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