Board Paper of Class 12-Science 2004 Biology Delhi(SET 1) - Solutions
(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.
- Question 1
Name the condition in humans in which the blood cholesterol content becomes abnormally high.VIEW SOLUTION
- Question 2
- Question 3
Many villagers near Industrial area suffer from "blue baby syndrome". How is this problem caused?VIEW SOLUTION
- Question 4
A cardiologist observed an elevated ST Segment in the ECG of a patient. What is it indicative of?VIEW SOLUTION
- Question 5
Why is quarantine a must before introduction of a plant species from a different country?VIEW SOLUTION
- Question 6
What is meant by apoplast pathway? Why does it occur in cortex and not in endodermis?VIEW SOLUTION
- Question 7
Where is pneumotoxic centre located in humans? What is its significance in breathing?VIEW SOLUTION
- Question 8
How is a disease-resistant plant selected for successful breeding?VIEW SOLUTION
- Question 9
Why is the process of fertilisation in a flowering plant referred to as double fertilisation? Explain.VIEW SOLUTION
- Question 10
Name the watery fluid secreted from Brunner's gland in the duodenum. Mention its any two characteristics. What role does it play inside the duodenum?VIEW SOLUTION
- Question 11
How is opening and closing of stomata controlled? Explain.VIEW SOLUTION
- Question 12
Why is the length of a food chain in an ecosystem generally limited to 3 − 4 trophic levels? Explain with an example.VIEW SOLUTION
- Question 13
In what form do the terrestrial reptiles excrete their nitrogenous waste? How is this kind of excretion advantageous to the land vertebrates which lay shelled eggs?VIEW SOLUTION
- Question 14
Explain briefly how computed tomography (CT) helps the doctors in pinpointing the defects in the patient's body.VIEW SOLUTION
- Question 15
What is eutrophication? Explain with reference to aquatic ecosystem.
Name any two source organisms of agar. List any four areas in which agar has wide application.VIEW SOLUTION
- Question 16
Name the two groups of nephrons on the basis of their position in the kidney. How are they different from each other?VIEW SOLUTION
- Question 17
How is the halophyte Rhizophora adapted to survive in its habitat? Explain.VIEW SOLUTION
- Question 18
When and why does photo-respiration take place in plants? How does this process result in a loss to the plant?VIEW SOLUTION
- Question 19
Explain the sliding filament theory of muscle contraction.VIEW SOLUTION
- Question 20
What is special of "FlavrSavr" variety of tomato? Why is it preferred to its normal native variety?VIEW SOLUTION
- Question 21
Draw a labelled sketch of L.S. of a human grinding tooth fixed in the socket.
Draw a schematic diagram to show the spinal reflex arc. Label the components of the pathway.VIEW SOLUTION
- Question 22
Name the organism involved in symbiotic nitrogen fixation. What are the components needed for this process? Explain their role.VIEW SOLUTION
- Question 23
Differentiate between inbreeding and heterosis. The outcome of which one is superior in performance and why?VIEW SOLUTION
- Question 24
What is the optimum percentage of forest area recommended by the National Forest Policy (1988) for the plains and the hills respectively? List any four problems caused due to deforestation.VIEW SOLUTION
- Question 25
Why is the human placenta referred to as haemochorial type? Name the hormone it secretes to facilitate parturition.VIEW SOLUTION
- Question 26
Where does Calvin cycle take place in chloroplast? Explain the cycle.
Where is electron transport system operative in mitochondria? Explain the system highlighting the role of oxygen.VIEW SOLUTION
- Question 27
Describe the hormonal control of the reproductive system in human male.VIEW SOLUTION
- Question 28
Define totipotency. Explain the two different routes of regenerating plantlets from callus culture.VIEW SOLUTION