CBSE 12TH BIOLOGY - Online Test
Q1. Primary constituents of photochemical smog are
Answer : Option A
Explaination / Solution:
Photochemical smog is a mixture of air pollutants which have been chemically altered into further noxious compounds by exposure to sunlight. The main components of photochemical smog are nitrogen oxides, Volatile Organic Compounds (VOCs), tropospheric ozone, and PAN (peroxyacytyl nitrate).The smog causes poor visibility on roads and airports.
Q2. In pBr322, B and R stands for
Answer : Option C
Explaination / Solution:
Plasmid vector Pbr322 is a multipurpose cloning vector. In pBr322, B and R stand for Boliver and Rodriguez who discovered this cloning vector.
Q3. Which one of the followings is also called Sewall Wright Effect?
Answer : Option D
Explaination / Solution:
Sewall Wright was the chief developer of the mathematical theory of genetic drift, which is sometimes known as the Sewall Wright effect, cumulative stochastic changes in gene frequencies that arise from random births, deaths, and Mendelian segregations in reproduction.
Q4. We can save those water reservoirs which are useful for irrigation, by
Answer : Option B
Explaination / Solution:
We can save water reservoirs which are useful for irrigation by checking biotic succession. Biotic succession leads to silt formation at bottom that reduce the capacity of water reservoirs.
Q5. Radioactive probe can be detected by
Answer : Option A
Explaination / Solution:
Radioactive probes are single stranded DNA or RNA having radioactive components. This probe can be detected in the individual by using autoradiography technique.
Q6. Medical termination of pregnancy is considered safe up to _________ of pregnancy.
Answer : Option A
Explaination / Solution:
Medical termination of pregnancy is considered safe up to twelve weeks or three months. At the end of three months all organs of foetus are formed. It is fetal to mother in case of MTP after three months.
Q7. Dormancy is the
Answer : Option A
Explaination / Solution:
Dormancy is the state of state of inactivity during which metabolic process slows down. Seed may remain viable to several months to years depending upon type of seeds and condition.
Q8. To avoid decline or death of bacterial cells in culture we must
Answer : Option B
Explaination / Solution:
Culture medium provide all the nutrients required for the growth of bacteria. To avoid the death or decline of bacterial cells in medium, culture medium must be changed periodically.
Q9. Pollen grain germinate through
Answer : Option D
Explaination / Solution:
Pollen grain is two layered structure. The outer layer is called exine and inner layer is called intine. Exine is a hard covering, except at germ pore, through which pollen grain germinate.
Q10. Which of the following disease is caused by virus and transmitted by mosquito?
Answer : Option D
Explaination / Solution:
The Flavivirus causes yellow fever, and it's transmitted when an infected mosquito bites you. Mosquitoes become infected with the virus when they bite an infected human or monkey. The disease cannot be spread from one person to another.
