Ecosystems — BIOLOGY STD 12 Science — Question

Give the term/ reason:
Mechanism responsible for parturition.

Replication was allowed to take place in the presence of radioactive deoxynucleotides precursors in E.coli that was a mutant for DNA ligase. Newly synthesised radioactive DNA was purified and strands were separated by denaturation. These were centrifuged using density gradient centrifugation. Which of the following would be a correct result?

Categorise the following plants into hydrophytes, halophytes, mesophytes and xerophytes. Give reasons for your answers.

1. Salvinia.
2. Opuntia.
3. Rhizophora.
4. Mangifera.

Prashant's mother is suffering from a disorder for which doctor suggests her to take insulin injections. But his mother declines as she presumes injections are prepared by slaughtering of animals. Doctor smiled and explained him about the genetically engineered human insulin produced these days. He also convinced her to take injections.

1. Name the bacterium that is used to produce human insulin.
2. Name the company that first produced human insulin.
3. Name the disease that is treated by using human insulin.
4. What values are shown by the doctor?

With the help of suitable diagram describe the logistic population growth curve.

What is auto-defense? Describe autoimmune diseases in humans.

A tall pea plant with yellow seeds (heterozygous for both the traits) is crossed with a dwarf pea plant with green seeds. Using a Punnett square work out the cross to show the phenotypes and the genotypes of F₁ generation.

What develops into a microspore mother cell in a flower? Trace the development of this cell into a pollen grain which is ready for germination. Draw a labelled figure of a mature pollen grain.

What is rDNA? Explain the technique of cloning rDNA.