The diagram above is that of a typical biogas plant. Explain the

Subject

Biology

Class

CBSE Class 12

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 Multiple Choice QuestionsShort Answer Type

21. How are dominance, co-dominance and incomplete dominance patterns of inheritance different from each other?
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22.

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.

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23.

(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.

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24. What is inbreeding depression and how is it caused in organisms? Write any two advantages of inbreeding.
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25.

(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.

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26.


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


The sequences of events occurring in a biogas plant are:

(i) Hydrolysis: Through hydrolysis the complex organic molecules are broken down into simple sugars, amino acids and fatty acids.

(ii) Acidogenesis: In this step further breakdown of the remaining components by acidogenic (fermentative) bacteria takes place.

(iii) Acetogenesis: In this step simple molecule obtained by acidogenesis phase are further digested by acetogens, to produce largely acetic acid as well as carbon dioxide and hydrogen.

(iv) Methanogenesis: In this step methanogens utilize the intermediate products of the previous stages and convert them into methane, carbon dioxide and water.

The parts of biogas plant:

The part labelled (a) is sludge

The part labelled (b) is a gas holder, and

The part labelled (c) is inlet to feed slurry

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27.

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

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28.

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

(i) Morphine

(ii) Cocaine

(iii) Marijuana

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29.

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.

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 Multiple Choice QuestionsLong Answer Type

30.

(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

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