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Biology VVI Subjective Question Bihar Board English Medium |class 12th Biology Bihar Board |Biology class 12th

Biology VVI Subjective Question Bihar Board English Medium


1. Define Buds and Bulbils with the help of suitable examples.

Ans:-  Define Buds:

1. A small lateral or terminal protuberance on the stem of a plant that may develop.

2. into a flower, leaf, or shoot 2: something not yet mature or at full development

3. such as a an incompletely opened flower.


Define Bulbils:

1. A condensed auxiliary bud (vegetative) is called bulbil

2. It helps in vegetative reproduction. e.g., Dioscorea Gilabba, Agave, Oxalis

3. A small bulblike organ of vegetative reproduction growing in leaf axils or on flower

4. Stalks of plants such as the onion and tiger lily.


2. Explain Binary Fission and Multiple Fission with examples.

Ans:- Binary fission

1. Forms two daughter individuals

2. Divides only once

3. No residue is left

4. Takes place in favourable conditions

5. Immortality is present

Example:- Amocha

Reproduces by binary fission 


Multiple fission

1. Forms many daughter individuals

2. Divides repeatedly Residue is left

3. Takes place in favourable as well as unfavourable.conditions

4. Immortality is absent

Example:- Plasmodium

Reproduces through muhiple fission.


3. How many types of restriction enzymes are there? Write their names.

Ans:- Four types

Traditionally, four types of restriction enzymes are recognized, designated I, II, III and IV, which differ primarily in structure, cleavage site, specificity, and cofactors.


4. Define the f the following:

(A) Cloning site

(B) Microinjection

Ans:- Cloning Site

A Restriction enzyme site of group of sites (= multiple cloning site) located in a vector at the best position for insertion of DNA.



Microinjectionis a technique in which recomminant DNA is directly injected into the nucleus of an animal. In this, through a glass micropipette, foreign DNA is delivered directly into a living cell, oocyte or embryos of animal.


5. Write comments on practical adaptations in animal.

Ans:- Gifaffe:

Gifaffe are the tallest land mammals today, but they weren’t so tall a few million years ago. During the Miocene Epoch, nearly 25 million years ago, have a long neck, nor long. legs like its modern-day relatives.

However, the competition for food with other hervivores was rather stiff. However, the leaves in the taller shrubs and trees was an untapped niche. But only the animals with longer necks were able to graze on the foliage higher up in the tree.

So, traits that contained the genes for longer necks were passed down over many generations. Eventually, this adaptation led to the gradual evolution of animals with longer necks. 25 million years later, we have the tallest land inimal on earth today the giraffes.


6. Name any four genetic diseases.

Ans:-  1. Single gene inheritance

2. Multifactorial inheritance

3. Chromosome abnormalities

4. Mitochondrial inheritance


7. Define the following:

(A) Co-dominance

(B Imcomplete Dominance

(C) Dominant

(D) Recessive

Ans:- Recessive

Recessive is a quality found in the relationship between two versions of a gene. Individuals receive ofic version of a gene, called in allele, from each parent. If the alleles are different the dominant allele will be expressed, while the effect of the other allele, called recessive, is masked.



Codominancemeans that neither allele can mask the of the other allele. An example in humans would be expression of the other the ABO blonda ABO blood group Where a alleles and alleles Bare born expressed. So if an individual inherits allele A from their moder and allele B from their father, they have blood type AB.


Incomplete dominance

Incomplete dominance is when a dominant allele, or forn of a gene, does not completely mask the effects of a recessive allele, and the organism’s resulting physical appearance shows of both alleles. It is also called serni-dominance or a blending of partial dominance. One examples ce. One example is shown in roses.

Ominances is the phenomenon of one variant of a gene on a chromosome masking or overriding the effect of a different variantof the same gene on the other copy of the chromosome.


8. Define the operon and name its constituent genes.

Ans. An Operon is made up of several structural genes er a common promoter and regulated by a common operator. It is defined as a set of adjacent structural genes, plus the jacent regulatory signals that affect transcription of the the adjacent structural genes.

An Operon is made up of 3 basic DNA components: moter-A nucleotide sequence that enables a gene to the Promoter-A transcribed In the case of a repressor, the repressor protein physically obstructs the RNA polymerise from transcribing the genes. Structural genes-The genes that are co-regulated by the operon.

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