CBSE 12TH BIOLOGY - Online Test
Q1. Species are classified within a hierarchy reflecting:
Answer : Option D
Explaination / Solution:
Classification of organisms are done on the basis of evolutionary hierarchy that is older organisms are classified first and recently evolved species later on.
Q2. What is the number of sperms released in vagina in single insemination?
Answer : Option B
Explaination / Solution:
In single insemination during coitus about 200-300 millions of sperms are released in the vagina of female. About 60% of them must have normal shape and size along with vigorous motility for fertilisation of ovum.
Q3. Two genes R and Y are located very close on the chromosomal linkage map of maize plant. When RRYY and rryy genotypes are hybridized, the F2 segregation will show:
Answer : Option B
Explaination / Solution:
Two genes located very close on the chromosomal linkage map. Segregation of R and Y will not takes place due to linkage and passes to same gamete together but overall segregation can be expected as usual as dihybrid cross, 9:3:3:1.
Q4. Semi-conservative replication of DNA was first demonstrated in
Answer : Option A
Explaination / Solution:
Semi-conservative replication of DNA was first demonstrated in bacterium Escherichia coli as it contain single chromosome within the cell without nuclear membrane.
Q5. Which of the following is a not a green house gas
Answer : Option D
Explaination / Solution:
Green house gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect.
Many greenhouse gases occur naturally in the atmosphere, such as carbon dioxide, methane, water vapor, and nitrous oxide, while others are synthetic. Those that are man-made include the chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs) and Perfluorocarbons (PFCs), as well as sulfur hexafluoride (SF6). Oxygen is not a green house gas.
Q6. PCR was discovered by
Answer : Option D
Explaination / Solution:
Polymerase chain reaction (PCR) was discovered by Kary Mullis. PCR technique is used to amplify the DNA segments to obtain large number of identical copies.
Q7. Which of the following examples of variation is not important from an evolutionary standpoint?
Answer : Option D
Explaination / Solution:
Biological evolution refers to the cumulative changes that occur in a population over time. Non-genetic changes that occur during an organism's life span, such as increases in muscle mass due to exercise and diet,differences due to health, age or accident that have no affect on an individual's ability to survive and reproduce cannot be passed on to the next generation and are not examples of evolution.
Q8. The first order consumers are called:
Answer : Option B
Explaination / Solution:
Plants and algae make their own food and are called primary producers. Herbivores eat plants and are called primary consumers.
Q9. DNA is denatured to produce single strand by
Answer : Option C
Explaination / Solution:
Deoxyribose nucleic acid is denatured to produce single stranded by using alkaline solution. DNA is acidic in nature, in alkaline solution the hydrogen bonds between the nitrogenous bases is broken to separate two strands.
Q10. Human population growth is
Answer : Option A
Explaination / Solution:
Human population growth is exponential growth which gets doubled every time. The newly produced individual also participates in population increase after attaining puberty.
