CBSE 12TH BIOLOGY - Online Test
Q1. The process of growing whole plants from explant is called
Answer : Option A
Explaination / Solution:
The process of growing whole plants form any part of plant (explant) is called tissue culture. In this process part of plant is grown in test tube under sterile condition in special nutrient.
Q2. Which of the following is a vulnerable species (as per 2008 red list):
Answer : Option B
Explaination / Solution:
The IUCN Red List of Threatened Species (also known as the IUCN Red List or Red Data List), founded in 1964, is the world's most comprehensive inventory of the global conservation status of biological species.
Vulnerable species are likely to become endangered unless something changes. Polar bear is likely to become endangered due to climate change. So, polar bear is vulnerable species as per 2008 red book list.
Q3. Each testicular lobules contain one to three highly coiled
Answer : Option C
Explaination / Solution:
Testicular tubules are present inside the testis. Each testicular lobule contains one to three highly coiled seminiferous tubules. Seminiferous tubules contain two types of cells male germ cells and sertoli cells.
Q4. Crossing over brings
Answer : Option C
Explaination / Solution:
Crossing over brings recombination or new combination of genes and hence variations. It occurs during cell division in prophase stage of meiosis-I.
Q5. Cyanobacteria serves as important biofertilizers in the fields of
Answer : Option C
Explaination / Solution:
Rice field contain water all the time. In this water Cyanobacteria grows easily that have ability to fix atmospheric nitrogen into nitrates and nitrites that increase the fertility.
Q6. A gas produced by paddy fields and involved in global warming is
Answer : Option D
Explaination / Solution:
Anaerobic decomposition of plants in water produces methane gas in paddy field. This gas is involved in global warming as methane is a green house gas beside carbon dioxide.
Q7. Electroporation helps in the introduction of foreign DNA into target organism by
Answer : Option D
Explaination / Solution:
Electroporation, or electropermeabilization, is a microbiology technique in which an electrical field is applied to cells in order to increase the permeability of the cell membrane, allowing chemicals, drugs, or DNA to be introduced into the cell.
In microbiology, the process of electroporation is often used to transform bacteria, yeast, or plant protoplasts by introducing new coding DNA.
Q8. The process of evolution of different species in a given geographical area starting from a point and radiating to other geographical area is called
Answer : Option B
Explaination / Solution:
In evolutionary biology, adaptive radiation is a process in which organisms diversify rapidly from an ancestral species into a multitude of new forms, particularly when a change in the environment makes new resources available, creates new challenges, or opens new environmental niches.
Q9. Hydra reproduce asexually by
Answer : Option D
Explaination / Solution:
In Hydra small outgrowth develops at the bottom side which grows into a bud. The well-developed buds detach from the parent body as new individual.
Q10. Earth crust is the reservoir of sedimentary type of nutrients like
Answer : Option A
Explaination / Solution:
Earth crust is the reservoir of sedimentary type of nutrients like phosphorus. Atmosphere is the reservoir of gaseous types of cycle like oxygen and nitrogen along with carbon.
