Evolution — BIOLOGY STD 12 Science — Question

Provide genetic explanation for the observation in which the flower colour in F₁ generation of snapdragon did not resemble either of the two parents. However, the parental characters reappeared when F₁ progenies were selfed.

1. You are given tall pea plants with yellow seeds, whose genotypes are unknown. How would you find the genotype of these plants? Explain with the help of cross.
2. Identify A, B and C in the table given below:

Pattern of Inheritance	Monohybrid F1 Phenotypic Expression
Codominance	‘A’
‘B’	Progeny resembled only one of the parents.
Incomplete dominance.	‘C’

1. Why are herbivores considered similar to predators in the ecological context? Explain.
2. Differentiate between the following interspecific interactions in a population:

1. Mutualism and Competition.
2. Commensalism and Amensalism.

Name the law that states that the sum of allelic frequencies in a population remains constant. What are the five factors that influence these values?

What is cancer? How is a cancer cell different from normal cell? How do normal cells attain cancerous nature?

Describe the functions of the following:
Epididymis.

1. Draw the embryo sac of a flowering plant and label:

1. Central cell
2. Chalazal end of the embryo sac
3. Synergids.

2. Name the cell that develops into the embryo sac and explain how this cell leads to the formation of embryo sac. Also mention the role played by the various cells of the embryo sac.

Give an account of the methods used in sequencing the human genome.

What are the advantages and disadvantages of cross-pollination?