Model Paper 1 — BIOLOGY STD 12 Science — Question

1. Given below is the TS of human ovary. Identify the following in the diagram:

• Corpus luteum.
• Secondary oocyte.
• Antrum.
• Primary follicle.
• Primary oocyte.

2. Explain the changes the primary oocyte undergoes while in different follicular stages before ovulation.

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You have a friend whose parents are too indulgent in his/her daily affairs. They think him/her to be still young which makes him/her sad and is upset all the time. As he/she feels that the parents should give him/her opportunity to take independent decision on some issues.

1. Would you support your friend and why?
2. Write the characteristics of this age group.
3. List two curative measures.

The following is the illustration of the sequence of ovarian events (a – i) in a human female.

Write the difference between ‘c’ and ‘h’.

(a) Write the features that a biomolecule must fulfill to be able to act as a genetic material.
(b) DNA and RNA are both genetic materials. Which one of the two is more stable and why?
Or
Stability of DNA is higher than that of RNA. How?

What does an Ecological Pyramid indicate? Explain the three different types of Upright Pyramids in nature with the help of an example of each.

Species diversity decreases as we move away from the equator towards the poles. What could be the possible reasons?

Elaborate how invasion by an alien species reduces the species diversity of an area.

Describe the steps involved in the sequencing of genome of an organism.

Explain evolution with the help of its embryological evidences.###Explain evidence from embryology in evolution.

What role does pituitary gonadotropins play during follicular and ovulatory phases of menstrual cycle and also explain the shift in steroidal secretions.