Science (English Medium) Class 12 - CBSE Question Bank Solutions for Biology

On the ribosome, mRNA binds ______ and two sites in the ______ for subsequent amino acids to bind to be close enough to each other for the formation of a peptide bond. 

The pedigree chart given below shows a particular trait which is absent in parents but present in the next generatoin irrespective of sexes. Draw your conclusion on the basis of the pedigree.

A normal visioned woman, whose father is colour blind, marries a normal visioned man. What would be probability of her sons and daughters to be colour blind? Explain with the help of a pedigree chart.

What are the functions of methylated guanasine cap?

What are the functions of poly-A “tail” in a mature on RNA?

Give an account of post transcriptional modifications of a eukaryotic mRNA.

Study the Pedigree chart given below and answer the questions that follow:

Symbols used in the given Pedigree Chart are as follows:

	Carrier male
	Affected male
	Normal male
	Carrier female
	Affected female
	Normal female

(a) On the basis of the inheritance pattern exhibited in this pedigree chart, what conclusion can you draw about the pattern of inheritance?

(b) If the female is homozygous for the affected trait in this pedigree chart, then what percentage of her sons will be affected?

(c) Give the genotype of offspring 1, 2, 3 and 4 in III generations.

OR

(c) In this type of inheritance pattern, out of male and female children which one has less probability of receiving the trait from the parents? Give a reason.

Observe the segment of mRNA given below.

(a) Explain and illustrate the steps involved to make fully processed hnRNA?

(b) Gene encoding RNA Polymerase I and III have been affected by mutation in a cell. Explain its impact on the synthesis of a polypeptide, stating the reasons.

What should be the genotype of the indicated member?

• Assertion: Ribosomal RNA is synthesized in the nucleus of the cell.
• Reason: It is translated with the enzyme RNA polymerase III.

Some organisms suspend their metabolic activities to survive in unfavourable conditions. Explain with the help of any four examples.

Give an example of a codon having a dual function.

Angiosperms bearing unisexual flowers are said to be either monoecious or dioecious. Explain with the help of one example each.

A non biology person is quite shocked to know that apple is a false fruit, mango is a true fruit and banana is a seedless fruit. As a biology student how would you satisfy this person?

Describe the development of endosperm after double fertilisation in an angiosperm.

Draw a labelled mature stage of a dicotyledonous embryo.

Why does endosperm development preceeds that of zygote ?

Describe the development of an endosperm in a viable seed. Why does endosperm development precedes embryo development?

Why does endosperm development precede embryo development in angiosperm seeds?

Write the contributions of the following scientists in deciphering the genetic code.
George Gamow; Hargobind Khorana; Marshall Nirenberg; Severo Ochoa