Human Reproduction — BIOLOGY STD 12 Science — Question

A garden pea plant bearing terminal, violet flowers, when crossed with another pea plant bearing axial, violet flowers, produced axial, violet flower and axial, white flowers in the ratio of 3 : 1. Work out the cross showing the genotypes of the parent pea plants and their progeny.

Draw a diagrammatic sketch of the sectional view of a typical anatropous ovule.

OR

Draw a labelled diagram of the sectional view of a typical anatropous ovule.

Answer the following questions:
Draw a diagram of a mature human male gamete. Label the following parts: Acrosome, nucleus, middle piece and tail.

Describe the process of decomposition of detritus under the following heads: Fragmentation; leaching; catabolism; humification andmineralisation.

Study the illustration given and answer the questions that follow:

Explain the role of hormones in the formation and release of ‘a’.

Explain the development of a secondary oocyte (ovum) in a human female from the embryonic stage upto its ovulation. Name the hormones involved in this process.

OR

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

Mention the biological factors of ecology.

Using Punnett square demonstrate the law of independent assortment in a dihybrid cross involving two heterozygous parents.

Drugs and alcohol give short-term 'high' and long-term ‘damages’, Discuss.

(i) What is called immunity?
(ii) Write the difference between active immunity and passive immunity. (Sr. Sec. Board Exam., 2023)
(iii) Explain passive immunization. (iv) Make a labeled diagram of the stages of life cycle of Plasmodium in mosquito host.