Biology: 2004:CBSE:[ Delhi ]:Set-I
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Q1
Name the condition in humans in which the blood cholesterol content becomes abnormally high.
Marks:1View AnswerAnswer:
Blood cholesterol becomes abnormally high during Hypertension.
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Q2
Define vernalisation. Marks:1View AnswerAnswer:
Vernalization – This is the chilling treatment of the plant responsible for an early flowering in them.
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Q3
Many villagers near industrial area suffer from "blue baby syndrome". How is this problem caused? Marks:1View AnswerAnswer:
The disease can be caused by in-take of water and vegetables high in nitrate, exposure to chemicals containing nitrate, or it can even be hereditary. -
Q4
A cardiologist observed an elevated St segment in the ECG of a patient. What is it indicative of? Marks:1View AnswerAnswer:
Elevation of ST region in an ECG signifies abnormal Ventricular contraction due to myocardial infarction.
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Q5
Why is quarantine a must before introduction of a plant species from a different country?
Marks:1View AnswerAnswer:
It is essential to protect managed crops and natural flora from harmful pests and diseases.
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Q6
What is meant by apoplast pathway? Why does it occur in cortex and not in endodermis? Marks:2View AnswerAnswer:
Apoplast is defined as free space outside the plasma membrane which facilitates transport of water and solutes across a tissue or organ. The phenomenon of transport in plants through apoplast is called Apoplast pathway.
Endodermis cells consist of a waxy substance called Suberin that resist water and form distinctive Casparian strips. Thereby, preventing the movement of water via apoplast pathway.
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Q7
Where is pneumotoxic centre located in humans? What is its significance in breathing? Marks:2View AnswerAnswer:
Pneumatic centre is a group of neurons present in the Pons region of the brain. It can moderate the respiratory rhythm by sending a neural signal to reduce the duration of inspiration and finally the respiratory rate.
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Q8
How is a disease-resistant plant selected for successful breeding? Marks:2View AnswerAnswer:
In the selection of disease-resistant plants for successful breeding : - First of all, the plants are exposed to the disease causal organisms. - After that, those plants will be selected which do not show any symptoms of the disease. - These will be self pollinated for 2-3 generations and after confirmation, if these plants are not showing any symptoms in these generations, these will be used for breeding experiments. -
Q9
Why is the process of fertilization in a flowering plant referred to as double fertilization? Explain.
Marks:2View AnswerAnswer:
The process of fertilization in a flowering plant referred to as double fertilization because in angiosperms (flowering plants) during reproduction, two sperm nuclei from pollen tube fertilize two cells in an ovary. One of the two sperm cells fertilities the egg cell forming a diploid (2n) zygote (syngamy). The other sperm cell fuses with two haploid polar nuclei in the centre of the embryo sac (or ovule). The resulting cell is triploid (3n).
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Q10
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? Marks:2View AnswerAnswer:
Out of syllabus
