Evolution — BIOLOGY STD 12 Science — Question

According to Global Hunger Index, 2014, two billion people suffer from hidden hunger. Apply your knowledge of plant breeding techniques to suggest a programme to improve public health. Specify four objectives of the programme. Also, mention one example of such a produce.

Why didn’t natural selection lead to the evolution of such totally harmless parasites?

How Jhum cultivation has lead to deforestation in recent years?

What are the preventive measures against ascariasis?

1. Sickel-cell anaemia in humans is a result of point mutation. Explain.
2. Write the genotypes of both the parents who have produced a sickle-cell anaemic offspring.

Describe the embryonic development of a zygote upto its implantation in humans.

Draw a sectional view of seminiferous tubule of a human. Label the following cells in the seminiferous tubule:

1. Cells that divide by mitosis to increase their number.
2. Cells that undergo Meiosis I.
3. Cells that undergo Meiosis II.
4. Cells that help in the process of spermiogenesis.

OR
Draw a labelled sectional view of seminiferous tubule of a human male.

What are sacred groves? What is their role in conservation?

Sketch and label Seminiferous tubules as seen in T.S. of testis.

What is a test cross? How can it decipher the heterozygosity of a plant?