QUESTIONS
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- You are provided with plant specimens labelled E, F, G, H, and J. Use the specimens to develop a dichotomous key that can be used to identify the plants from which they were obtained based on the following characteristics in the order they are given: (6 marks)
- Leaf form
- Leaf venation
- Leaf colour
- Account for the likely observation if fresh specimen E was exposed to light and tested for starch. (3 marks)
- Explain one observable feature that adapts plants from which specimen G and H were obtained to a dry environment. (2 marks)
- Besides leaf characteristics, state one other observable characteristic on the plant from which specimen F was obtained that enables it to be placed in its Class. (1 mark)
- You are provided with plant specimens labelled E, F, G, H, and J. Use the specimens to develop a dichotomous key that can be used to identify the plants from which they were obtained based on the following characteristics in the order they are given: (6 marks)
- You are provided with solution M which is a food substance.
Procedure- Using the reagents provided, test for the food substance present in substance M and complete the table below. (12 marks)
Food Test Procedure Observation Conclusion - State two precautions one should observe while conducting the experiment in 2(a) (2 marks)
- Using the reagents provided, test for the food substance present in substance M and complete the table below. (12 marks)
- You are provided with specimen N and P which are plants of the same species grown under different conditions.
- State two observable differences between the two specimens. (2 marks)
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- Name the phenomenon observed in specimen N. (1 mark)
- Explain how the knowledge on the phenomenon named in bi) is applied in agriculture(2 marks)
- Account for the appearance of specimen N. (3 marks)
- State two other environmental factors necessary for seed germination apart from light. (2 marks)
- State two observable features on the specimens that make them be placed in the same Class. (2 mark)
MARKING SCHEME
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- Leaf simple ....go to 2
Leaf compund....G - Leaves/leaf network veined ....go to 3
LeavEs/leaf parallel veined...F - Leaves/leaf green/non variegated ...G/H or go to 4
Leaves/leaf non-green/ variegated ....E - Leaf margin serrated.....G
Leaf margin smooth.....H
- Leaf simple ....go to 2
- Green parts/ parts with chlorophyll will turn blue black (with iodine solution/iodine) due to presence of starch since photosynthesis has occurred; white parts turn to brown/retain iodine solution; due to absence of starch since photosynthesis has not occured
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- Rough/ hairy leaf surface; to reduce transpiration.
Leaves fold; to reduce transpiration - Shiny/ glossy leaf surface; to reduce transpiration folding of leaves; to reduce water loss
- Rough/ hairy leaf surface; to reduce transpiration.
- Fibrous root system;
Floral parts in threes/ multiples of three
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Food Test Procedure Observation Conclusion Starch To about 2ml of food substance (in a test tube). Add 2 drops of iodince solution Color of iodine retained/ yellow brown;
Reject; no change/ no observable change
Accept; no color changeStarch absent
Vitamin C(Absorbic acid) To about 2ml of DCPip in a test tube. Add a drop of the food substance /M DCPip is decolorised or DCPip becomes colorless Vitamin C present Lipids Put/rub a drop of M onto the filter paper/ plain paper(allows the drop to drip)
Hold against a source of lightNo translucent
Mark left (on the filter paper)Lipids absent -
- Avoid contamination of reagants/ aparatus/ avoid mixing of droppers/use clean apparatus
- Avoid burning of filter paper/ plain paper when dripping
- Avoid spilling/ misusing of regants/food substance
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N
Yellow leaves/ white green/ yellow stem
small leaves
Long stem/tall stem/long internodes
thin stem
Weak/ fragile/feeble/frain stemP
Green leaves/green stem
large/big leaves
Sort stem/short internodes
thick stem
strong/firm stem -
- Etiolation
- Proper spacing/thinning/pruning/pricking out/weeding/using a transparent material/polythene on a green house; to enable adequatee penetration of light for the crop
- The specimen is weak/tall/long/thin; because they have grown in a darkness;/ absence of light/ insufficient light; in darkness there is high concentration of auxin in shoot tip that stimulate faster elongation;
OR
The specimen has small/ yellow leaves/white stem/ lack of chlorophyll; because they were grown in darkness; hence couldn't carry out photosynthesis/ synthesis of chlorophyll - Oxygen
Water/moisture
Optimal/optimum temperature/warmth; - Tap root system
Reticulate/network venation/branched venation/net-veined leaves;
Broad leaves
Compact petiole
Accept presence of two cotyledon
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