This Class 12 Biology Practical aims to help students understand Mendelian inheritance by studying the colour and size of seeds from any plant, such as pea or bean. Mendel’s laws—Law of Dominance, Law of Segregation, and Law of Independent Assortment—explain how traits pass from parents to offspring. In this experiment, students observe dominant and recessive characters like yellow vs. green seeds or round vs. wrinkled seeds.
To perform this practical, collect seeds of two contrasting traits, mix them, and classify them based on appearance. Record the number of each phenotype and compare your ratio with Mendel’s expected 3:1 ratio for monohybrid crosses or 9:3:3:1 for dihybrid crosses.
This practical helps students clearly understand genetic patterns, Punnett squares, and real-life applications of heredity. It is an important experiment for CBSE Class 12 exam preparation and biology project work.
AIM: To study Mendelian inheritance using seeds of different colour/size of any plant.
REQUIREMENTS
Pea seed sample, enamel tray, petri dishes, notebook pencil/pen,
PROCEDURE
1. Take a lot of about 100 pea seeds in an enamel tray.
2 Separate out round and wrinkled seeds and put them in separate Petri dishes.
3. Note down the number of round and wrinkled seeds and calculate their approximate ratio.
4. Repeat the process for the other contrasting trait of the seed i.e. yellow and green colour.
OBSERVATIONS
Present your findings in the form of a table given below, Data related to two finding is given in the table, record your finding in the same way.
CONCLUSION
The contrasting forms in both the traits of pea seed (i.e., seed shape pue seed colour) show as approximate ratio of 3:1 This ratio is exactly the same as obtained by Mendel for monohybrid crosses and indicate that the dominant and recessive forms of seed shape and seed colour exist in the ratio of 3:1 in the population of pea seeds.
PRECAUTIONS
L Take a sufficiently large number of seed lot for analysis to minimise the error.
2. Observe the contrasting form of the trait carefully,
Class 12 Biology Lab Manual – Final Practicals | Complete Lab Experiment File
A. List of Experiments
1. Prepare a temporary mount to observe pollen germination.
2. Study the plant population density by quadrat method.
3. Study the plant population frequency by quadrat method.
4. Prepare a temporary mount of onion root tip to study mitosis.
5. Isolate DNA from available plant material such as spinach, green
pea seeds, papaya, banana etc.
B. Study and observe the following (Spotting):
1. Flowers adapted to pollination by different agencies (wind, insects, birds).
2. Pollen germination on stigma through a permanent slide or scanning electron
3. Identification of stages of gamete development, i.e., T.S. of testis and T.S. of
ovary through permanent slides (from grasshopper/mice).
4. Meiosis in onion bud cell or grasshopper testis through permanent slides.
5. T.S. of blastula through permanent slides (Mammalian).
6. Mendelian inheritance using seeds of different colour/sizes of any plant.
7. Prepared pedigree charts of any one of the genetic traits such as rolling of tongue,
blood groups, ear lobes, widow's peak and colour blindness.
8. Controlled pollination - emasculation, tagging and bagging.
9. Common disease causing organisms like Ascaris, Entamoeba, Plasmodium, any
fungus causing ringworm through permanent slides, models or virtual images or
specimens. Comment on symptoms of diseases that they cause.
10. Models specimens showing symbiotic association in lichens, root nodules of
leguminous plants, and parasitic mode of nutrition shown by Cuscuta on host.
11. Flash cards / models showing examples of homologous and analogous organs.
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Biology
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