CBSE 12TH BIOLOGY - Online Test
Q1. Which of the following control the function of Sertoli cell?
Answer : Option A
Explaination / Solution:
FSH (follicle stimulating hormone) stimulates Sertoli cells to secrete spermatogenic substance. Sertoli cells function as nurse cells for differentiating spermatozoa.
Q2. Shifting cultivation practiced in India is called
Answer : Option B
Explaination / Solution:
Shifting cultivation practiced in India is called jhum cultivation in which forest is cleaned for agriculture practice and after few years this area is abandoned and another forest land is cleared.
Q3. Genetic drift is found in
Answer : Option B
Explaination / Solution:
Genetic drift is found in small population with or without mutated genes. Loss of some member of species having small population leads to decrease in variation called genetic drift.
Q4. Natural method of birth control in which the couples avoid from coitus from day 10 to 17 of menstrual cycle is called
Answer : Option C
Explaination / Solution:
periodic abstinence is a natural method of birth control in which the couples avoid from sexual intercourse form day 10 to 17 of menstrual cycle during which ovulation takes place in female.
Q5. What does "lac" refer to in what we call the lac operon?
Answer : Option D
Explaination / Solution:
The lac operon (lactose operon) is an operon required for the transport and metabolism of lactose in Escherichia coli and many other enteric bacteria. Although glucose is the preferred carbon source for most bacteria, the lac operon allows for the effective digestion of lactose when glucose is not available.
Q6. Egg released by the Graafian follicle is surrounded by
Answer : Option A
Explaination / Solution:
One of the two ovary release one egg by the Graafian follicle. The egg released is surrounded by two layers called zonapellucida and Vitelline membrane as protective layer.
Q7. Floods can be checked by
Answer : Option B
Explaination / Solution:
Floods can be checked by reforestation. The roots of plants binds the soil and act as barrier in flow of flood water to reduce its current speed.
Q8. Which one of the followings is incorrect about genetic drift?
Answer : Option B
Explaination / Solution:
Genetic drift is significant only in small population. Larger population has more variation and more species. Loss of some member of that species does not reduce variation essential for evolution.
Q9. A vasectomy prevents the
Answer : Option D
Explaination / Solution:
Vasectomy is the surgical method of birth control in which vas deference of male is cut and tide to prevent release of sperm into vagina during coitus.
Q10. The primary control of gene expression takes place at the level of
Answer : Option D
Explaination / Solution:
Expression of gene starts with transcription of particular segment of DNA, so primary control of gene expression takes place at the level of transcription of DNA into m-RNA.
