Human Reproduction — BIOLOGY STD 12 Science — Question

Kanchan went to a garden and saw some flowers which were closed. She assumed that those flowers must be buds. But she was astonished to see that all the flowers of that plant were closed and none of them was open. She was confused and asked her queries to her teacher.

1. What do you think, are there any plants with closed flowers? Give an example.
2. Are such plants get pollinated? Explain.
3. What are such flowers/ plants called?
4. What values are shown by Kanchan?

What could be the possible explanation for greater vulnerability of amphibians to extinction as compared to other animal groups?

Define the term addiction. Name some drugs which are normally used as medicines but are often abused.

Mention the prevention and control efforts by the population to prevent and control several infectious diseases? How can prevention and control of infectious diseases be done?

Explain with the help of an example the relationship between restriction endonuclease and a palindromic nucleotide sequence.

The length of a DNA molecule in a typical mammalian cell is calculated to be approximately 2.2m. How is the packaging of this long molecule done to accommodate it within the nucleus of the cell?

Louis Pasteur’s experiments, if you recall, proved that life can arise from only pre-existing life. Can we correct this as life evolves from pre-existent life or otherwise we will never answer the question as to how the first forms of life arose? Comment.

Expand 'ELISA'. Why is this method preferred over conventional methods of diagonsis of the disease?

Answer the following questions:
Describe the endosperm development in coconut.