CBSE 12TH BIOLOGY - Online Test
Q1. A mature ovarian follicle is called
Answer : Option C
Explaination / Solution:
A mature ovarian follicle is called Graafian follicle which consists of antrum and follicular cells.
Q2. Crossing over occurs at
Answer : Option B
Explaination / Solution:
Crossing over occurs at four strand stage of panchytene of meiosis-I. Each homologous chromosome has two stands. Exchange of gene occurs during this period.
Q3. The term antibiotic was coined by
Answer : Option A
Explaination / Solution:
The term antibiotic was coined by Selman Abraham Waksman. He developed antibiotic Streptomycin that cure tuberculosis. He got noble prize in medicine in 1952.
Q4. The biological amplification of DDT in the various trophic levels is known as
Answer : Option A
Explaination / Solution:
Biomagnification, also known as bioamplification or biological magnification, is the increasing concentration of a substance, such as a toxic chemical, in the tissues of organisms at successively higher levels in a food chain.
The biological amplification of DDT in the various trophic levels is known as biomagnifications.
Q5. The smallest bands in the agarose gel will be towards
Answer : Option D
Explaination / Solution:
Gel electrophoresis technique involves separation of different segments of DNA according to their size. The smallest bands in the agarose gel will be towards positively charged anode.
Q6. Evolution and natural selection is demonstrated by
Answer : Option C
Explaination / Solution:
Evolution and natural selection can be demonstrated by DDT resistance in Mosquito. Earlier, mosquitoes are not resistance to DDT. They get killed due to presence of DDT but later on more DDT is used and due to natural selection mosquito become resistant to DDT.
Q7.
Identify the organism and type of reproduction in figure below
Answer : Option B
Explaination / Solution:
Asexual mode of reproduction in yeast takes place by budding process in which small outgrowth develops on tips followed by karyokinesis. Same process is repeated several times to form chain of yeast cells.
Q8. Forests controls drought through
Answer : Option B
Explaination / Solution:
The volume of water retained by forests can depend on characteristics such as forest cover area, the length of vegetation growing season, tree composition and tree density, as well as the age and the number of layers of vegetation cover. Water retention by forests affects the amount and timing of the water delivered to streams and groundwater by increasing and maintaining infiltration and storage capacity of the soil. Forests can soak up excess rainwater, preventing run-offs and damage from flooding. By releasing water in the dry season, forests can also help provide clean water and mitigate the effects of droughts. Drought is due to less rainfall.
Q9. Before use of mice for vaccine testing which animals were used to test the safety of batches of vaccine?
Answer : Option C
Explaination / Solution:
The batches of vaccine are tested for safety before use on human beings. Earlier vaccine batches are tested on monkey but now transgenic mice are used to test the safety of vaccine.
Q10. Avoiding prostitution and homosexuality to get away from genital warts is called
Answer : Option A
Explaination / Solution:
Prophylaxis is the preventive method to avoid any disease which may be fatal to the person. Genital warts is caused by prostitution and homosexuality. Prophylaxis includes use of condom and other methods to get direct contact between two partners.
