Question 1
Using the cork borer provided bore out three long pieces of potato tissues. Measure out and cut three 3 cm cylindrical pieces.
Take the pieces of potato tissue and place each into a separate test-tube labeled D, e and F respectively.
Fill test tube D with solution labeled L1
Fill test-tube E with solution labeled L2
Leave test-tube F blank, I.e add no liquid to it
Allow the experiment to stand for 30 minutes
- After 30 minutes, remove one piece of tissue at a time; dry it with blotting paper and
measure its length. Record your measurements in the table below.
- Account for the observation made in the measurements of each tissue after 30 minutes in test tubes labeled D and E above.
D
E - What was the purpose of test – tube F and its content.
- Crush the rest of the potato into paste using a pestle and mortar and add little water to make a suspension and stir. Carry out food tests on the suspension using the reagents provided. Fill your answers in the table below.
Answer
- - Tissue in L1 should be shorter tham 3cm
- Tissue in L2 should be longer than 3cm
- tissue intest tube F (blank) should be 3cm. - D - 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 to 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 - It acted as a control experiment
Question 2
The diagrams below represent body parts of some organisms (animals). Study them and answer the question that follow.
-
- Suggest the type of food eaten by organisms with the parts labeled A, B, C and F
- With reasons, suggest the likely habitat of the organism from which the parts labeled D and E were obtained.
- Suggest the type of food eaten by organisms with the parts labeled A, B, C and F
-
- Suggest the type of evolution that is exemplified by the organisms labeled D, E and F. Give reason for your answer.
The type of evolution
Reason - Suggest the significance of the above named type of evolution for the organism
- Suggest the type of evolution that is exemplified by the organisms labeled D, E and F. Give reason for your answer.
Answer
-
-
-
- Divergent evolution;
Reason: Similar basic structure and embryonic origin but modified into different -
forms / appearance.
(2mks) Enable the organisms / animals to utilize different ecological niches to avoid competition for food.
- Divergent evolution;
