Evolution — BIOLOGY STD 12 Science — Question

1. Draw a labelled schematic diagram of a replication fork showing continuous and discontinuous replication of DNA strands.
2. State a reason why is the replication continuous and discontinuous in the diagram drawn.

Some parents wrote a complaint letter to the local municipality to remove all the hoardings in the city, advertising the use of condoms and matters relating to AIDS prevention. The children of these parents came to know about the matter and raised their voice against removal of the hoardings. The parents were convinced by the awareness level of their children and withdrew the complaint.

1. Parents considered the hoarding as inappropriate. Do you agree/ disagree with their view?
2. What are the methods by which AIDS spreads?
3. What is AIDS?
4. What values are promoted by the children protesting against their parents?

Inheritance pattern of ABO blood groups in humans shows dominance, codominance and multiple allelism. Explain each concept with the help of blood group genotypes.

Explain with the help of two examples, how certain plants have evolved morphological and chemical defenses against primary consumers such as cows and goats.

1. One of the codons on mRNA IS AUG. Draw the structure of RNA adapter molecule for this codon.
2. Name the RNA polymerase that transcribes RNA in eukaryotes.
3. What is unique about the amino acid this RNA binds with?

Gene expression can be controlled with the help of RNA molecule. Explain the method with an example.

Why is earthworm considered a farmer's friend? Explain humification and mineralisation occurring in a decomposition cycle.

Write any four facts proved by the study of fossils regarding the development of life?

The following graph represents the organismic response to certain environmental condition (e.g., temperature):

1. Which one of these, ‘a’ or ‘b’, depicts conformers?
2. What does the other line graph depict?
3. How do these organisms differ from each other with reference to homoeostasis?
4. Mention the category to which humans belong.

Given below is a list of autotrophs and heterotrophs. With your knowledge about food chain, establish various linkages between the organisms on the principle of ‘eating and being eaten’. What is this inter-linkage established known as?
Algae, hydrilla, grasshopper, rat, squirrel, crow, maize plant, deer, rabbit, lizard, wolf, snake, peacock, phytoplankton, crustaceans, whale, tiger, lion, sparrow, duck, crane, cockroach, spider, toad, fish, leopard, elephant, goat, Nymphaea, Spirogyra.