CBSE 12TH BIOLOGY - Online Test
Q1. The number of autosomes in human primary spermatocyte is
Answer : Option A
Explaination / Solution:
Primary spermatocytes are diploid and contain 23 pairs (46) of chromosomes. These chromosomes are divided into autosomes and sex chromosome. Sex chromosomes are XY and remaining chromosomes are called autosomes.
Q2. Chipko movement originated in
Answer : Option D
Explaination / Solution:
Chipko movement originated in Terhi Garwal of Utter Pradesh to protect the forest form contractors. In this movement women of village hug the tree to prevent it from cutting.
Q3. Single step large mutation is called
Answer : Option A
Explaination / Solution:
Evolution for Darwin was gradual while deVries believed mutation caused speciation. The single large mutation is called saltation.
Q4. A mother of one year old daughter wanted to space between her children. The best contraceptive method she should use is
Answer : Option B
Explaination / Solution:
Copper-T is a contraceptive method under intra uterine contraceptive device which prevents the implantation and reduce the motility of sperm. It is implanted inside the uterus and works up to five years. So, it is the best method for spacing between two children.
Q5. The sequence of structural gene in lac operon concept is
Answer : Option A
Explaination / Solution:
In lac operon concept the sequence of arrangement of structural gene is as lac Z, lac Y and lac A. The z gene codes for beta-galactosidase. The y gene code for permease and a gene encodes a transacytylase.
Q6. A human female is born with a million of primary oocytes at the time of birth. How many eggs get a chance to mature?
Answer : Option B
Explaination / Solution:
Girls are born with 200-300 millions of primary oocytes but all of these oocytes do not get chance to mature and change into ovum because one ovary produce only one ovum each month in the middle of menstrual cycle. So, about 500 eggs are released by female during her reproductive life.
Q7. Deforestation does not lead to
Answer : Option A
Explaination / Solution:
Deforestation does not lead to quick nutrient cycling but it may leads to soil erosion, alteration of local weather conditions and destruction of natural habitat of wild animals.
Q8. Which of the following sentences is incorrect about microspheres?
Answer : Option D
Explaination / Solution:
Microspheres are molecules developed during organic evolution. They do not have all properties of life. They are composed of protein molecule and form buds to develop smaller microspheres.
Q9. Absence of menstruation during period of intense lactation following parturition is called as
Answer : Option A
Explaination / Solution:
During intense lactation just after the delivery the menstrual cycle get stopped and there is no chance of pregnancy. This absence of menstruation is called lactational amenorrhea.
Q10. Removal of RNA polymerase III from nucleoplasm will affect the synthesis of
Answer : Option B
Explaination / Solution:
During transcription of m-RNA, removal of RNA polymerase III form nucleoplasm will affect the synthesis of t-RNA. The t-RNA transfers the amino acids to the site of translation to form protein.
