Ecosystems — BIOLOGY STD 12 Science — Question

What is nitrogen cycle? Describe it briefly.

A large number of married couples the world over are childless. It is shocking to know that in India the female partner is often blamed for the couple being childless.
Why in your opinion the female partner is often blamed for such situations in India?

Taking a small pond as an example of an ecosystem, list the four components of this ecosystem. How do these components function as a unit in a small pond?

State and explain the “law of independent assortment” in a typical Mendelian dihybrid cross.

Try to trace the various components of human evolution (hint: brain size and function, skeletal structure, dietary preference, etc.)

Describe the morphology of thyroid gland. Or With the help of a suitable diagram describe the structure of thyroid gland.

Sunny was rushed to a nearby hospital after an accident, which had caused too much blood loss. The hospital failed to supply 'O' negative blood for transfusion. Ahmed, who was attending a patient there, heard about the situation and agreed to donate blood as he had the same blood group. Sunny's mother initially refused but was later convinced by her daughter's view.

1. Why cannot 'O' positive blood be transfused into Sunny's body?
2. What is the genetic basis of blood group inheritance?
3. Human blood grouping is an example of?
4. What values do you find in Sunny's sister and Ahmed?

Why is aerobic degradation more important than anaerobic degradation for the treatment of large volumes of waste waters rich in organic matter. Discuss.

Over-exploitation.

Name any two chromosomal aberration associated disorders.