Biotechnology: Principles and Processes — BIOLOGY STD 12 Science — Question

Let us assume in a given plant the genotype symbol “Y” stands for dominant yellow seed colour and “y” for recessive green seed colour; symbol “R” for round seed shape and “r” for wrinkled seeds.
Two homozygous parents (plants) with genotypes “RRYY” and “rryy” are crossed and their F_1–generation progeny is then selfed. What shall be the:

1. Phenotype of F₁–progeny.
2. Genotype of F₁–progeny.
3. Gamete genotypes of F₁–progeny.
4. Phenotypic ratio of F₂ population.
5. Phenotypic ratio of yellow seed to green seed and round seed to wrinkled seed in F₂ population.

Though the conflict between humans and wildlife started with the evolution of man, the intensity of conflict has increased due to the activities of modern man. Justify your answer with suitable examples.

What do you understand by conservation? Describe the methods how biological resources are conserved?

Describe the post-zygotic events leading to implantation and placenta formation in humans. Mention any two functions of placenta.

OR

1. Briefly explain the events of fertilisation and implantation in an adult human female.
2. Comment on the role of placenta as an endocrine gland.

Give the term/ reason:
Why does zona pellucida layer block the entry of additional sperms?

What is tissue culture? What are the different types of tissue culture? Describe briefly.###Write an essay on tissue culture.

When does oogenesis start in humans? Name the three hormones and their source, linked with oogenesis. How do they influence the process of oogenesis? Explain.

(i) Define the cross-pollination.
(ii) Give one example each of aluminious, exalbuminous, perispermic seeds.
(iii) Draw a well labelled diagram showing the growth of pollen tube in longitudinal section of pistil.

How is the phenotypic ratio of F₂ generation different in a dihybrid cross?

What are the advantages and disadvantages of cross-pollination?