List of top Biology Questions asked in PSEB XII

The initiator codon, AUG codes for which of the following amino acids?
Which of the following is correct according to Chargaff's rules?
Heart shaped embryo is the feature of:
The number of megaspores formed from one megaspore mother cell is:
The cavity present in the blastula is called:
The method of directly injecting a sperm into ovum in assisted reproductive technology is called:
BOD stands for:
Transplantation of tissues/organs to save certain patients often fails due to rejection of such tissues/organs by the patient. Which type of immune response is responsible for such rejections?
Emergency contraceptives are effective if used within:
If the amount of adenine in a DNA is 30%, then according to Chargaff's rules, the amount of Uracil and Guanine present in the DNA respectively are:
During spermatogenesis, the number of sperms that are formed from 40 spermatogonia, 30 primary spermatocytes, 25 secondary spermatocytes and 15 spermatids respectively are:
Main cause of Klinefelter's syndrome is:

Observe the given diagram and answer the following questions. 
(Note: This question refers to the mice experiment with S-strain and R-strain bacteria) 

a) Who performed this experiment? 
b) What was the conclusion after this experiment? 
c) Write the results of the experiment A - D 
 

Observe the given diagram and answer the following questions. 
(Note: This question refers to the standard diagram of Microsporogenesis in flowering plants) 

a) Which type of cell division occurs in the diagram marked A 
b) The two cells formed in B are called ________ 
c) In figure marked C, four cells are formed. What are they? 
d) What happens to the cells marked C? 
e) What is the total process called? 
 

How can the loss of biodiversity be prevented?
Read the passage carefully and answer the following questions:
A constant input of solar energy is the basic requirement for any ecosystem to function and sustain. Primary production is defined as the amount of biomass or organic matter produced per unit area over a time period by plants during photosynthesis. It is expressed in terms of weight (g m⁻²) or energy (kcal m⁻²). The rate of biomass production is called productivity. It is expressed in terms of g m⁻² yr⁻¹ or (kcal m⁻²) yr⁻¹ to compare the productivity of different ecosystems. It can be divided into gross primary productivity (GPP) and net primary productivity (NPP). Gross primary productivity of an ecosystem is the rate of production of organic matter during photosynthesis. A considerable amount of GPP is utilised by plants in respiration. Gross primary productivity minus respiration losses (R) is the net primary productivity (NPP).
a. Define gross primary productivity.
b. What is the main requirement of ecosystem functioning?
c. What is the unit of productivity?
d. GPP $-$ Respiration = ________
With help of diagram, show the steps of recombinant DNA technology.
What is gene therapy? Illustrate using the example of adenosine deaminase deficiency.
Describe the individuals with the following chromosomal abnormalities:
1. Trisomy of chromosome 21.
2. XXY.
3. XO.
Write a short note on industrial melanism.
Name and explain the type of interaction between clown fish and sea anemone.
Define Oogenesis. Briefly describe the process of Oogenesis with the help of labelled diagram.
Name the causing agent of Typhoid. Also write down its symptoms and modes of transmission.
What are bioreactors. Name its two types.
Expand PCR. Mention its any one importance in biotechnology.