ISC Class XII Exam Question Papers 2012: Biology Practical

BIOLOGY
Paper – 2
(Practical)
(Three hours)
(Canal‑idles are allowed o‑ddiIiona115 minutes for only reo‑dirtg the paper.
They must NOT start w ‘nting during this time.)

………………………………………………………………………………………………………………………….

 Answer all questions.

All working, including rough work, should be done on the same sheet as the rest of the answer.

The intended marks for questions or parts of questions are given in brackets [ ].

………………………………………………………………………………………………………………………… .

Question 1        [5]

(a)Examine carefully the flower specimen D41 provided. Describe its floral characters in semi-technical terms. (Details of individual whorls are not required.)

(b)With the razor blade provided, cut a longitudinal section of one flower. Draw a neat diagram of one of the cut surfaces and label all the parts.

(c) Take a fresh specimen and remove the petals one by one with the help of forceps. Arrange the petals on a wet filter paper and draw a neat labelled diagram of all the petals.

(d) Now, observe the essential whorls of the specimen from (c) above.

(i) Draw a neat labelled diagram of the essential whorls without removing any part.

(ii) Comment on the following features of the androecium:

(1) Number of stamens.

(2) Nature of attachment of anthers.

(3)  Relation of stamens to each other.

(e) Remove the androecium and observe the gynoecium.

(i) Draw a neat labelled diagram of the gynoecium.

(ii) Comment on the position of the ovary with respect to the other whorls.

(iii) Cut a transverse section of the ovary. Make a labelled diagram of its cross- sections.

(iv) Mention the type of placentation.

(f) Write the floral formula of specimen D41.

(g) Draw the floral diagram of the specimen D41.

(h) State the botanical name of the specimen.

(i)  Name the family to which this specimen belongs.

(j) Mention the botanical name of one economically important plant of the same family other than the specimen D41.

Question 2       [6]

You are provided with twigs of plant D42 and glassware to set up an experiment to demonstrate photosynthesis. Set up the experiment using one or two twigs of D42. and tap water. Keep the apparatus near a light source.

(a) Draw a labelled diagram of the experimental set up.

(b) When gas bubbles start emerging from the cut ends of the twig(s), show the set up to the Visiting Examiner.

(c) Count the number of bubbles evolved in one minute and record it. Repeat your observation for two more readings. Tabulate the three readings and calculate the average number of bubbles (x) evolved in one minute.

(d) Prepare 10% solutio of NaHCO3 (Sodium bicarbonate). Add 10 ml of this solution to the experimental set up. Stir the water with the glass rod. Wait for three minutes. Count the number of bubbles evolved in one minute. Take three readings and calculate the average number of bubbles (y).

(e) Add another 10 ml of freshly prepared NaHCO3 solution to the set up and stir the water with the glass rod. Wait for three minutes. Count the number of bubbles evolved In one minute. Take three readings and calculate the average number of bubbles (z). Tabulate you observations as follows:

Experimental set up               Number of bubbles evolved per minute       Average Value

Initial — just tap water.

                                                                      (i) ______________

                                                                      (ii) _____________

.                                                                     (iii) _____________                                                x ____________________

After adding 10 ml of 10%                   (i) ___________

NaHCO3 solution                                     (ii) ___________

.                                                                        (iii) ___________                                                 y__________________

After adding another 10 ml                 (i) ___________

of 10% NaHCO3 solution                       (ii) ___________

.                                                                        (iii)_____________                                              z____________________

(f)Name the plant specimen D42.

(g)Comment briefly on the observations made by you regarding the recorded average values {x. y and z) of the bubbles evolved per minute.

(h)What do you conclude from this experiment?

(i)Mention any two precautions you have taken while performing this experiment.

Question 3                    [4]

(a) Cut thin section of D43 provided with a sharp razor blade. Cut numerous sections and then select a good section. Stain it with safranin. Mount it in glycerine. Observe it under the low power of a microscope and show it to the Visiting Examiner.

(b) Draw a neat labelled oufiine diagram of the mount as seen under the microscope. (Microscopic/structural details are not required.)

(c) (i) Identify the section. (ii) Given two reasons in support of your answer in (c) (i) above. 4

Question 4        [5]

(i) Identify the given specimens A to E and give two reasons to support your answer in each case.

(ii) Draw a neat labelled diagram of each specimen.

Note: You are not allowed to spend more than three minutes for each spot.

Question 5       [10]

Show the following to the visiting Examiner for assessment:

(a) Project.                   (b) Biology Practical File.

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