Model Paper 4 — BIOLOGY STD 12 Science — Question

Why are lymph nodes and bone marrow called lymphoid organs? Explain the functions of each of them.

From what you have learnt, can you tell whether enzymes are bigger or DNA is bigger in molecular size? How did you know?

What are antibiotics? Name the classes of organisms that produce antibiotics

Study the given pedigree chart and answer the questions that follow.

1. Is the trait recessive or dominant?
2. Is the trait sex linked or autosomal?
3. Give the genotypes of the parents shown in generation I and their III child shown in generation II and the first grandchild shown in generation III.

When a cross in made between tall plant with yellow seeds (TtYy) and tall plant with green seed (Ttyy), what proportions of phenotype in the offspring could be expected to be,

1. Tall and green.
2. Dwarf and green.

What is meant by biological evolution?

This image highlights the process of Gene Therapy of ADA-SCID.

i. Mention the cause of ADA deficiency in humans.
ii. How has genetic engineering helped patients suffering from it?

1. Mention the specific geographical region where these organisms are found.
2. Name and explain the phenomenon that has resulted in the evolution of such diverse species in the region.
3. Explain giving reasons the existence of placental wolf and Tasmanian wolf sharing the same habitat.

Draw a well labelled diagram of mature graafian follicle.

Your classmate complains of headache and cough. The doctor confirms that he is suffering from Pneumonia and not common cold, on the basis of certain symptoms. List these symptoms. Mention any two precautions to be followed to prevent the spread of this disease.