12th Biology Paper Solutions Set 1 : CBSE Delhi Previous Year 2011

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 :

Name the type of cell division that takes place in the zygote of an organism exhibiting haplontic life cycle.


Answer :

The type of cell division occurring in the zygote of an organism exhibiting haplontic life cycle is meiosis.

Q2 :

Write the scientific name of the microbe used for fermenting malted cereals and fruit juices.


Answer :

Saccharomyces cerevisiae is used in the fermentation of malted cereals and fruit juices.

Q3 :

Write the unit used for measuring ozone thickness.


Answer :

The thickness of the ozone layer is measured in Dobson units (DU).

Q4 :

Name the event during cell division cycle that results in the gain or loss of chromosome.


Answer :

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

How can bacterial DNA be released from the bacterial cell for biotechnology experiments?


Answer :

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

Write the importance of cryopreservation in conservation of biodiversity.


Answer :

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

Mention the role of the codons AUG and UGA during protein synthesis.


Answer :

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

Normally one embryo develops in one seed but when an orange seed is squeezed many embryos of different shapes and sizes are seen. Mention how it has happened.


Answer :

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

How do histones acquire positive charge?


Answer :

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

Why is CuT considered a good contraceptive device to space children?


Answer :

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

Differentiate between albuminous and non-albuminous seeds, giving one example of each.


Answer :

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

Explain the process of RNA interference.


Answer :

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

List the key tools used in recombinant DNA technology.


Answer :

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

Name the two types of immune systems in a human body. Why are cell mediated and humoral immunities so called?

OR

Write the scientific names of the causal organisms of elephantiasis and ringworm in humans. Mention the body parts affected by them.


Answer :

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

Justify with the help of an example where a deliberate attempt by humans has led to the extinction of a particular species.


Answer :

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

Identify A, D, E and F in the diagram of an antibody molecule given below.


Answer :

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

Study the graph given below. Explain how is oxygen concentration affected in the river when sewage is discharged into it.


Answer :

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

Explain how a hereditary disease can be corrected. Give an example of first successful attempt made towards correction of such diseases.


Answer :

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

Draw a diagram of a male gametophyte of an angiosperm. Label any four parts. Why is sporopollenin considered the most resistant organic material?


Answer :

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

How are dominance, co-dominance and incomplete dominance patterns of inheritance different from each other?


Answer :

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

The base sequence in one of the strands of DNA is TAGCATGAT.

(i) Give the base sequence of its complementary strand.

(ii) How are these base pairs held together in a DNA molecule?

(iii) Explain the base complementarity rules. Name the scientist who framed this rule.


Answer :

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

(a) Sickle celled anaemia in humans is a result of point mutation. Explain.

(b) Write the genotypes of both the parents who have produced a sickle celled anaemic offspring.


Answer :

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

What is inbreeding depression and how is it caused in organisms? Write any two advantages of inbreeding.


Answer :

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

(a) Identify (A) and (B) illustrations in the following:

(i)

(ii)

(b) Write the term given to (A) and (C) and why?

(c) Expand PCR. Mention its importance in biotechnology.


Answer :

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

The diagram above is that of a typical biogas plant. Explain the sequence of events occurring in a biogas plant. Identify a, b and c.


Answer :

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

How can crop varieties be made disease resistant to overcome food crisis in India? Explain.

Name one disease resistant variety in India of:

(a) Wheat to leaf and stripe rust

(b) Brassica to white rust

OR

Write the source and the effect on the human body of the following drugs:

(i) Morphine

(ii) Cocaine

(iii) Marijuana


Answer :

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

Name the type of interaction seen in each of the following examples:

(i) Ascaris worms living in the intestine of human

(ii) Wasp pollinating fig inflorescence

(iii) Clown fish living among the tentacles of sea-anemone

(iv) Mycorrhizae living on the roots of higher plants

(v) Orchid growing on a branch of a mango tree

(vi) Disappearance of smaller barnacles when Balanus dominated in the Coast of Scotland.


Answer :

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

(a) Draw a labelled diagram of the human female reproductive system.

(b) Enumerate the events in the ovary of a human female during:

(i) Follicular phase

(ii) Luteal phase of menstrual cycle

OR

(a) Write the specific location and the functions of the following cells in human males:

(i) Leydig cells

(ii) Sertoli cells

(iii) Primary spermatocyte

(b) Explain the role of any two accessory glands in human male reproductive system.


Answer :

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

Explain the salient features of Hugo de Vries theory of mutation. How is Darwin”™s theory of natural selection different from it? Explain.

OR

(a) Name the primates that lived about 15 million years ago. List their characteristic features.

(b) 

(i) Where was the first man-like animal found?

(ii) Write the order in which Neanderthals, Homo habilis and Homo erectus appeared on earth. State the brain capacity of each one of them.

(iii) When did modern Homo sapiens appear on this planet?


Answer :

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

(a) Explain primary productivity and the factors that influence it.

(b) Describe how do oxygen and chemical composition of detritus control decomposition?

OR

(a) What is El Nino effect? Explain how it accounts for biodiversity loss.

(b) Explain any three measures that you as an individual would take, to reduce environmental pollution.


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.