Science (English Medium) इयत्ता १२ - CBSE Question Bank Solutions for Biology

Catalytic converters are fitted into automobiles to reduce emission of harmful gases. Catalytic converters change unburnt hydrocarbons into ______.

Why is it necessary to remove sulphur from petroleum products?

Use of lead-free petrol or diesel is recommended to reduce the pollutants emitted by automobiles. What role does lead play?

Name the city in our country where the entire public road transport runs on CNG.

What is hybrid vehicle technology? Explain its advantages with a suitable example?

Which of the following amino acid residues will constitute the histone core?

Given below is the Age Pyramid of the population in one of the states in India as per 2011 census. It depicts the male population on the left-hand side, female population on the right-hand side, newborns towards the base and gradually increasing age groups as we move from base to the top, with the oldest population at the top. Study this pyramid and comment upon the appropriateness of the Assertion and the Reason.

                              Percentage to the total population

Assertion: It is a stable population.

Reason: The pre-reproductive and reproductive individuals are almost in equal numbers and the post-reproductive individuals are relatively fewer.

CTTAAG
GAATTC

1. What are such sequences called? Name the enzyme used that recognizes such nucleotide sequences.
2. What is their significance in biotechnology?

Carefully observe the given picture. A mixture of DNA with fragments ranging from 200 base pairs to 2500 base pairs was electrophoresed on agarose gel with the following arrangement.

(a) What result will be obtained on staining with ethidium bromide? Explain with reason.

(b) The above setup was modified and a band with 250 base pairs was obtained at X.

What change(s) were made to the previous design to obtain a band at X? Why did the band appear at position X?

Write the best method to measure the population density of a single Banyan tree in comparison to Partlzenium weeds in a forest by an ecologist. Explain and justify your answer.

Name the drug a patient who has undergone a successful organ transplant, has to take all his/her life.

Given below is an equation describing the Species-Area relationship between species richness and area for a wide variety of taxa as angiosperm plants, birds, bats etc. S = CA^z

1. Give a graphical representation of the given equation showing Species-Area relationship.
2. What does 'S' represent in the given equation?
3. What is the value of 'Z' (regression coefficient) for frugivorous birds and mammals in the tropical forests of different continents?

State the most important contribution of the following microbes for human welfare:

Monascus purpureus

State the most important contribution of the following microbes for human welfare:

Trichoderma Polysporum

What would be the best method to measure the total population density of a dense bacterial culture in a petridish and why?

Identify the type of pyramid given above. Write the identifying feature on the basis of which you identified it. 

Write the inference drawn by Alexander von Humboldt after his extensive explorations of South American jungle.

Study the graph given below:

As per Alexander von Humboldt, what do the symbols S, A, Z and C in the graph stand for, in respect of a species and area relationship?

Given below is the stepwise schematic representation of the process of electrophoresis. Identify the 'alphabets' representing 

1. Anode end
2. smallest/lightest DNA strand in the matrix
3. Agarose gel

What is elution?