CBSE 12TH BIOLOGY - Online Test
Q1. Functional and dynamic unit of nature where living and non-living components interact with each-other is
Answer : Option C
Explaination / Solution:
An ecosystem is a dynamic complex of plant, animal and micro-organism communities and the abiotic environment interacting as a functional unit. Ecosystems are not static but dynamic and discontinuous systems with interactions and connections which continually evolve both spatially and temporally. They represent ecological processes and the resources they provide can be expressed in terms of goods and services.
Q2. The best way to obtain bacteria and viruses free plants through tissue culture is
Answer : Option C
Explaination / Solution:
Many important plants contain systemic viruses which substantially reduce their potential yield and quality. It is, therefore, important to produce virus free stocks which can be multiplied. Generally, highly meristematic tissue of a virus infected plant remains free from virus due to their fast mitotic activity. Therefore, shoot tips and meristems of a virus infected plant are the ideal explants to produce a virus free stock.
Q3. If we say, India has about 50,000 type of rice and 1000 types of varieties of mango what level of diversity it indicates:
Answer : Option B
Explaination / Solution:
India has about 50,000 type of rice and 1000 types of varieties of mango. This high level of diversity indicates very high genetic diversity and one of the largest in the world.
Q4. When there is no distinction of sepals and petals, the non-essential floral organs are collectively called
Answer : Option C
Explaination / Solution:
In some flowers, there is no distinction of sepals and petals. In these flowers these non-essential organs are together called as perianth. The individual parts of perianth are called tepals.
Q5. Prostate gland and seminal vehicle perform the function of
Answer : Option A
Explaination / Solution:
Prostate gland and seminal vehicle provide nutrient to sperm and also provide fluid medium for the motility of sperm.
Q6. The best method to determine the homozygous and heterozygous of an individual is
Answer : Option A
Explaination / Solution:
Homozygous and heterozygous of an individual is determined by test cross method in which homozygous recessive is crossed with F1 hybrid individual.
Q7. Vinegar is obtained from molasses with the help of
Answer : Option C
Explaination / Solution:
Vinegar is chemically diluted acetic acid which is produced by fermentation of molasses in presence of yeast and Acetobactor.
Q8. Which of the following is a line source of air pollution?
Answer : Option B
Explaination / Solution:
A line source, as opposed to a point source, area source, or volume source, is a source of air, noise, water contamination or electromagnetic radiation that emanates from a linear (one-dimensional) geometry.
A smoking person while walking is line source of air pollution as the smoke released by smoking person spread in linear direction.
Q9. Parrots have life span of about
Answer : Option C
Explaination / Solution:
The life span of parrot is about 140 years. It is much more than other common animals living in our surrounding. Even more than human being life span.
Q10. Lysozyme kills bacteria by destroying
Answer : Option D
Explaination / Solution:
Lysozyme is capable of breaking the chemical bonds in the outer cell wall of the bacteria. Bacterial cell walls contain a layer of peptidoglycan, which is the specific site that lysozyme targets.
The peptidoglycan layer contains alternating molecules called N-acetylglucosamine and N-acetylmuramic acid. These molecules form a strong glycan chain that act as the backbone for the cell wall.
The link between the N-acetylglucosamine and N-acetylmuramic acid is cleaved by lysozyme. Once this chain is broken by lysozyme, it results in bacterial death.
