12th Biology Paper Solutions Set 1 : CBSE All India Previous Year 2004

General Instructions:
 (i) All questions are compulsory.
(ii) This question paper consists of four sections A, B, C and D.
Section A contains 5 questions of one mark each.
Section B is of 10 questions of two marks each.
Section C is of 10 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.
(iv) Wherever necessary, the diagrams drawn should be neat and properly labelled.
Q1 :

How is haemoglobin differently located in humans and earthworms?


Answer :

In human beings, haemoglobin is present in red blood cells (RBCs), while in earthworms, haemoglobin is dissolved in blood plasma.

Q2 :

What is apoptosis with reference to ageing?


Answer :

Apoptosis refers to the cell death that occurs as an organism ages.

Q3 :

What are the starting points of a grazing food chain and a detritus food chain respectively?


Answer :

Starting point of a grazing food chain are producers.

Starting point of a detritus food chain is dead and decaying organic matter.

Q4 :

A cardiologist observed an enlarged QR wave in the ECG of a patient. What does it indicate?


Answer :

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

Name the type of cells that produce antibodies.


Answer :

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

What is meant by Respiration Quotient (RQ)? When will the value of RQ be l and when will it be less than1?


Answer :

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

Explain any two functions of cerebrospinal fluid in humans.


Answer :

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

Name the organism that causes Anthrax in cattle. Why does the infected animal die within 2 or 3 days?


Answer :

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

Differentiate between quiescence and dormancy with reference to seed germination.


Answer :

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

How is our gut lining protected from its own secretion of proteases?


Answer :

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

Name the respective mineral nutrient element that

(i) forms the core constituent of the ring structure of chlorophyll

(ii) activates carboxylases

(iii) forms the component of nitrogenase

(iv) synthesises the middle lamella of plant cells


Answer :

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

What is photochemical smog composed of? How does this affect the plants?


Answer :

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

Define a portal vein. Explain the functions of such a vein in our digestive system.

OR

What is the role of calcium ions in muscle contraction?


Answer :

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

Why is aqueous gel applied between the skin and the scan head in sonography during clinical examination? Why is this technique generally preferred to radiography?


Answer :

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

Lichen is considered a good example of obligate mutualism. Explain.


Answer :

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

Name the T3 and T4 components of the thyroid hormone. Explain their specific action.


Answer :

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

Give a schematic representation of nitrogen cycle of a terrestrial ecosystem. Name any two microorganisms involved in it.


Answer :

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

Why does the rate of photosynthesis decrease at higher light intensities? What plays a protective role in such situations?


Answer :

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

Due to some physiological reasons the blood glucose level of an otherwise normal person has shot up above normal. How will this condition be returned to normal through hormone action?


Answer :

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

(i) Give the scientific name of the soil bacterium which produces crystal (Cry) proteins.

(ii) How are these proteins useful in agriculture?

(iii) What do the differently written terms “Cry” and “cry” represent respectively?


Answer :

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

Draw a labelled diagram to show the impulse conductive system in human heart.

OR

Draw a labelled sketch of human urinary system with its associated blood vessels.


Answer :

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

List the three prominent theories to explain water translocation in trees. Describe the most accepted theory out of these.


Answer :

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

How is an allopolyploid produced”™? Explain with an example.


Answer :

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

Differentiate between in situ and ex situ approaches of conserving biodiversity.


Answer :

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

Trace the development of a mature ovule from a megaspore mother cell.


Answer :

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

Where does glycolysis occur in a cell? Explain its different steps.

OR

Explain non-cyclic photophosphorylation in plants. Why is this process called so?


Answer :

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

Describe oogenesis in human female. What promotes completion of second meiotic division in oogenesis?


Answer :

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

Differentiate between inbred line and a hybrid variety of crop. Explain the steps involved in the production of the hybrid variety.


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.