Human Reproduction — BIOLOGY STD 12 Science — Question

What is the significance of ampullary–isthmic junction in the female reproductive tract?

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.

Name three incurable sexually transmitted diseases and their causative organisms.

Anita was happy when she gave birth to her first child. Her in-laws were dissatisfied at her not giving birth to a male child and blamed Anita. Anita tried to convince her in-laws that she had no role in the child's gender. They understood the biological reason but were yet to be satisfied. Anita's husband took up the matter and convinced the parents.
i. What values did Anita's husband show in the above situation?
ii. What governs sex determination in humans? How is it different from birds?
iii. Why can't Anita be blamed for not giving birth to a male child?

1. Differentiate between analogous and homologous structures.
2. Select and write analogous structures from the list given below:

1. Wings of butterfly and birds.
2. Vertebrate hearts.
3. Tendrils of bougainvillea and cucurbita.
4. Tubers of sweet potato and potato.

You have identified a useful gene in a bacteria. Make a flow chart of the steps that you would follow to transfer this gene to a plant.

What are biofertilizers? Name the two elements which are made available by them.

Study the graph given below and answer the question that follow:

1. Write the status of food and space in the curves (a) and (b).
2. In the absence of predators, which one of the two curves would appropriately depict the prey population?
3. Time has been shown on X-axis and there is a parallel dotted line above it. Give the significance of this dotted line.