12th Biology Paper Solutions Set 3 : CBSE Delhi Previous Year 2007

These are additional set 3 questions.
Q1 :

Mention the significant role of lymph capillaries (lacteals) in villi. 


Answer :

Lacteals or lymph capillaries collect absorbed fatty acids, which are then reconstructed into triglycerides.

Q2 :

In a wheat field, some broad-leaved weeds were seen by a farmer. Name the synthetic plant hormone you would suggest to the farmer to get rid of them. 


Answer :

Auxinis the hormone that can be added to check the growth of weeds. It is a generally used weedicide.

Q3 :

What is the starting point of a detritus food chain? 


Answer :

The starting point of a detritus food chain is dead organic matter.

Q4 :

Why is cardiac pacemaker a life-saving device?


Answer :

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Q5 :

A container is divided into compartments A and B using a semi permeable membrane. Compartment A is filled with 10 per cent sucrose solution and B with 5 per cent sucrose solution. Mention the direction in which the water will move between the two compartments. Name the process by which the water moves.


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Q6 :

What is biological nitrogen fixation? Name two organisms which fix nitrogen asymbiotically. 

OR

In which form do plants absorb potassium from the soil? List any two potassium deficiency symptoms in plants.


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Q7 :

Who discovered Sertoli cells? Mention their role in spermatogenesis.


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Q8 :

What is anthropogenic extinction? How is it different from mass extinction?


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Q9 :

Name the animal in which Rh factor was first discovered. Mention the problem expected to occur if an Rh− mother bears an Rh+ foetus in humans.


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Q10 :

Where do you find complex V in mitochondria? What is its role? 


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Q11 :

How do sciophytes and heliophytes adapt to different light intensities? Explain.


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Q12 :

In an autoimmune disorder, a person produces antibodies that mimic the action of TSH. Name the disorder which results due to this situation. Give its symptoms.


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Q13 :

Draw a sectional view of a pollen grain and label the following parts:

(1) Intine

(2) Exine

(3) Germ pore

(4) Generative cell


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Q14 :

What is AV node? Where is it located in the human body? Mention its function.

OR

What is meant by chloride shift? Where does it occur in the human body? What is its significance?


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Q15 :

Describe greenhouse effect and list two greenhouse gases.


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Q16 :

What is biomass fuel? Explain its significance. Name the process by which biomass is converted into biogas.


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Q17 :

What is haploidy? How are haploid plants raised? How are they helpful in plant breeding?


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Q18 :

What is endocrine theory of ageing? Write briefly the role of melatonin and DHEA hormones in ageing.


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Q19 :

Where are auxins synthesised in a plant? Explain any four of their applications.


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Q20 :

Explain the mechanism of opening and closing of stomata based on the roleof potassium ions.


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Q21 :

List the cause and the symptom of eachof the following in humans:

(1) Anaemia

(2) Pernicious anaemia

(3) Macrocytic anaemia


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Q22 :

What is myogenic mechanism of autoregulation of glomerular filtration? What is its importance?


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Q23 :

What is single-cell protein? How is it produced? Discuss its importance. In what ways is it useful to humans?


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Q24 :

Give a schematic representation of non-cyclic photophosphorylation showing both the photosystems.

OR

Give a schematic representation of the citric acid cycle. Where does it occur in a cell? 


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Q25 :

What is a synovial joint? What makes such a joint move freely? Describe any three kinds of synovial joints in the human body, giving one example of each.

OR

What is a “reflex action”™? With the help of an example describe the functions of the various components of a spinal reflex arc. 


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Q26 :

Explain the procedure involved in detecting the presence of antigen in a sample by ELISA. Why is ELISA specially recommended for detection of antigens?

OR

1. Discuss on what does the success of organ transplantation depend and how graft rejection can be prevented in humans.

2. Explain the following:

(a) Haplotype
(b) Autograft


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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.