12th Biology Paper Solutions Set 1 : CBSE Delhi Previous Year 2008

General Instructions:
(i) All questions are compulsory.
(ii) This question paper consists of four Sections A, B, C and D. Section A contains 8 questions of one mark each, Section B is of 10 questions of two marks each, Section C is of 9 questions of three marks each and Section D is of 3 questions of five marks each.
(iii) There is no overall choice. However, an internal choice has been provided in one question of 2 marks, one question of 3 marks and two questions of 5 marks weightage. A student has to attempt only one of the alternatives in such questions.
(iv) Wherever necessary, the diagrams drawn should be neat and properly labelled.
Q1 :

What causes speciation according to Hugo deVries?


Answer :

According to Hugo deVries theory, speciation occurs due to sudden appearance of mutations in existing populations. Such mutations are random and directionless and can cause speciation.

Q2 :

When and why do some animals such as frogs hibernate?


Answer :

Hibernation or winter sleep is a resting stage where animals such as frogs escape winters (cold) by hiding themselves in their shelters. They escape the winter season by entering a state of inactivity by slowing their metabolism.

Q3 :

List any two economically important products for humans obtained from Apis indica.


Answer :

Honey, cosmetics, and polishes are some of the economically important products obtained from Apis indica.

Q4 :

Name the Indian variety of rice patented by an American company.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q5 :

What role do macrophages play in providing immunity to humans?


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q6 :

Name the parts “A”™ and “B”™ of the transcription unit given below.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q7 :

Name the world”™s most problematic aquatic weed. What is the nature of the water body in which the weeds grow abundantly?


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q8 :

What is the major difference you observe in the offsprings produced by asexual reproduction and in the progeny produced by sexual reproduction?


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q9 :

The flower of brinjal is referred to as chasmogamous while that of beans is cleistogamous. How are they different from each other?


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q10 :

Name the interaction in each of the following:

(a) Cuckoo lays her eggs in the crow”™s nest.

(b) Orchid grows on a mango tree.

(c) Ticks live on the skin of dogs.

(d) Sea anemone is often found on the shell of hermit crab.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q11 :

A man with blood group A married a woman with B group. They have a son with AB blood group and a daughter with blood group O. Work out the cross and show the possibility of such inheritance.

OR

The male fruit fly and female fowl are heterogametic while the female fruit fly and the male fowl are homogametic. Why are they called so?


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q12 :

Why is using tobacco in any form injurious to the health? Explain.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q13 :

Differentiate between a detritivore and a decomposer giving an example of each.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q14 :

A mother of one year old daughter wanted to space her second child. Her doctor suggested CuT. Explain its contraceptive actions.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q15 :

Study the linking of DNA fragments shown above.

(i) Name “a”™ DNA and “b”™ DNA.

(ii) Name the restriction enzyme that recognises this palindrome.

(iii) Name the enzyme that can link these two DNA fragments.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q16 :

What is divergent evolution? Explain taking an example of plants.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q17 :

Name the blank spaces a, b, c, and d in the table given below:

Type of Microbe

Name

Commercial Product

Fungus

a

Penicillin

Bacterium

Acetobacter aceti

b

c

Aspergillus niger

Citric acid

Yeast

d

Ethanol


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q18 :

Thermal power plants are inevitable in an industrial and densely populated country like ours. What harm do they do to the environment? Also mention any precaution that could be taken to save our environment.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q19 :

Draw a labelled diagram of the microscopic structure of a human sperm.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q20 :

Expand MOET. Explain the procedure of this technology in cattle improvement.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q21 :

One of the codons on mRNA is AUG. Draw the structure of tRNA adapter molecule for this codon. Explain the uniqueness of this tRNA.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q22 :

Study the population growth curves in the graph given below and answer the questions which follow:

(i) Identify the growth curves ‘a’ and ‘b’.

(ii) Which one of them is considered a more realistic one and why?

(iii) If is the equation of the logistic growth curve, what does K stand for?

(iv) What is symbolised by N?


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q23 :

How and why is the bacterium Thermus aquaticus employed in recombinant DNA technology? Explain.

OR

(a) What are “molecular scissors”™? Give one example.

(b) Explain their role in recombinant DNA technology.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q24 :

Given below is a part of the template strand of a structural gene:

TAC

CAT

TAG

GAT

(a) Write its transcribed mRNA strand with its polarity.

(b) Explain the mechanism involved in initiation of transcription of this strand.

 


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q25 :

(i) How and at what stage does Plasmodium enter into a human body?

(ii) With the help of a flow-chart only, show the stages of asexual reproduction in the life-cycle of the parasite in the infected human.

(iii) Why does the victim show symptoms of high fever?


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q26 :

It has been recorded that the temperature of the earth”™s atmosphere has increased by 0.6°C.

(a) What has caused this increase?

(b) Explain its consequences.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q27 :

Explain the pattern of inheritance of haemophilia in humans. Why is the possibility of a human female becoming haemophilic extremely rare? Explain.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q28 :

Draw a labelled diagram of the sectional view of a mature pollen grain in angiosperms. Explain the functions of its different parts.

OR

Give a schematic representation of Oogenesisin humans. Mention the number of chromosomes at each stage. Correlate the life phases of the individual with the stages of the process.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q29 :

(a) Mention the role of vectors in recombinant DNA technology. Give any two examples.

(b) With the help of diagrammatic representation only, show the steps of recombinant DNA technology.

OR

(a) What is plasmid?

(b) What is meant by ADA deficiency? How is gene therapy a solution to this problem? Why is it not a permanent cure?


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q30 :

Explain Hershey-Chase experiment. What was proved through this experiment?

OR

(a) A true breeding pea plant, homozygous for inflated green pods, is crossed with another pea plant with constricted yellow pods (ffgg). What would be the phenotype and genotype of F1and F2generations? Give the phenotype ratio of F2generation.

(b) State the generalisation proposed by Mendel on the basis of the above mentioned cross.


Answer :

Please Register/Login to get access to all solutions Facebook Login

12th Biology Paper Solutions Set 3 : CBSE Delhi Previous Year 2013 will be available online in PDF book soon. The solutions are absolutely Free. Soon you will be able to download the solutions.