CBSE > Class 12 > Biology | CBSE Board | Homework Help

Chargaffs rule state that dna of any organism shoul have pyrimidine and purine present in 1:1i.e. amount of adenine should equal to amount of thymine and amount of guanine should be equal to amount of cytosine..

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Shefu ??????? 6 years, 2 months ago

Adenine + Thymine = Guanine + cytosine

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Which book ki prefer to get above 95 in biology

Posted by Nitika Sharma 6 years, 2 months ago

CBSE > Class 12 > Biology

3 answers

Aastha Saxena 6 years, 2 months ago

Ncert + Xam idea

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Shiristi Gujjar 6 years, 2 months ago

Ncert + xam idear

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Gargee K 6 years, 2 months ago

Ncert

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What are the Benefits of Apomixis????

Posted by Raman Kumar 6 years, 2 months ago

CBSE > Class 12 > Biology

3 answers

Muskaan Vig 6 years, 2 months ago

A seed is prepared with all desirable qualities using conventional plant breeding or mutation breeding...... when the seed will grow into a plant and fertilization has to take place to produce new seeds and with fertilization there will be segregation of character due to meiosis in female or male mother cell this will alter the quality of seed .........using apomixis we can grow a seed of parental type for several years.......

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Souromi Chatterjee 6 years, 2 months ago

Characters do not segregate.. helps the farmer as there is no separation of characters and easy to maintain hybrid character

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Raman Deep Singh 6 years, 2 months ago

Characters not segregate as there is no meiosis.

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What is homeostasis

Posted by Adeeba Alam 6 years, 2 months ago

CBSE > Class 12 > Biology

2 answers

Muskaan Vig 6 years, 2 months ago

Maintaining internal body temperature as required by body no matter what outside environment temperature is..Eg.humans shiver in winters to raise body temp. And sweat in summers to decrease body temp....so as to bring it to normal body temp 37°C... Homeostasis occurs because body enzymes of an organism works best at a particular temp...

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Raman Deep Singh 6 years, 2 months ago

Balanced internet environment is termed as homeostasis

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Rivet popper hypothesis given by

Posted by Vaibhav Maurya 6 years, 2 months ago

CBSE > Class 12 > Biology

2 answers

Shiristi Gujjar 6 years, 2 months ago

Paul ehlrich

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Sunita Sharms 6 years, 2 months ago

Paul ehrilh

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Which type of page used for critically endangered species in red data book(=red list)

Posted by Vaibhav Maurya 6 years, 2 months ago

CBSE > Class 12 > Biology

1 answers

Shefu ??????? 6 years, 2 months ago

Dark pink colour

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Define sexual deceit

Posted by Shiva Jms 6 years, 2 months ago

CBSE > Class 12 > Biology

1 answers

Muskaan Vig 6 years, 2 months ago

Deceit means to cheat... Sexual deceit is defined as process in which petal of flower resembles to female of insect like ? bee in size ,colour and markings. Explanation: Flowers develop this morphology to attract male bee who has pollen grains on his body (from any other flower) and pollinates the flower. The male bee in order to copulate with female bee which is actually the petal comes on the flower site and the flower get pollinated by deceiving the male flower..

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I want biology Investigatory project ..what are the best topics ??

Posted by Pritam Sharma 6 years, 2 months ago

CBSE > Class 12 > Biology

4 answers

Abhijeet Singh 6 years, 2 months ago

***

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Sunita Sharms 6 years, 2 months ago

Genetic engineering

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Taranveer Kaur 6 years, 2 months ago

Microbes in human welfare etc

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Taranveer Kaur 6 years, 2 months ago

Animal breeding Plant breeding Applications of biotechnology Tumour Tuberculosis Cancer

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What is the ideabehind Cornell elegant seafield test in seashores of Scotland

Posted by Sujit Kumar Roy 6 years, 2 months ago

CBSE > Class 12 > Biology

0 answers

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What is the reprrssure in lac operon

Posted by Anand Pandey 6 years, 2 months ago

CBSE > Class 12 > Biology

2 answers

Muskaan Vig 6 years, 2 months ago

Repressor is protein that binds to operator region in lac operon gene and prevents further genes (that are present further to operator and can only work when operator is not repressed ) to express itself.

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Yogita Ingle 6 years, 2 months ago

Gene regulation can be defined as any kind of alteration in the gene to give rise to a different expression which might result in a change in the synthesized amino acid sequence.

We can infer that the gene regulation can take place at various steps of gene expression which includes the following:

Replication level – Any error in copying the DNA may result in an altered expression.
Transcriptional level – During transcription, any error in the polymerization may again lead to a change in expression of the gene.
Post-transcriptional level – During the post-transcriptional modification i.e., RNA splicing, there may be some changes.
Translational level – During translation, if there is an error in the attachment of mRNA to the tRNA molecules, there may arise some changes.

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Difference between pericarp and prosper?

Posted by Geeta Goswami 6 years, 2 months ago

CBSE > Class 12 > Biology

1 answers

Yogita Ingle 6 years, 2 months ago

PERISPERM	PERICARP
It is unused nucellus in the seed.	It is the covering of fruit that develops from ovary wall.
It is a part of seed.	It is part of fruit.
It is usually dry.	It is dry or fleshy.
It is often non functional for seed.	It is protective covering and also helps in dispersal and nutrition.
Perisperm is present in only a few seeds.	It is found in all fruits.

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Bony fishes and reptiles produced more number of offsprings than mammals-Comment

Posted by Monika Patel 6 years, 2 months ago

CBSE > Class 12 > Biology

1 answers

Muskaan Vig 6 years, 2 months ago

Bony fishes and reptiles produce more no. Of offspring because their offspring are more vulnerable to predators and many of their offspring die .To compensate this loss and to gain natural fitness which can be gained if the organism has more offspring....bony fishes and reptiles has evolve to produce more offspring.More progeny, more natural fitness ,more survival.

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What is the common name of human

Posted by Abu Kapoor 6 years, 2 months ago

CBSE > Class 12 > Biology

4 answers

Itisha Bathla 6 years, 2 months ago

Homo sapien

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Rahul Dagar 6 years, 2 months ago

Ve yaa to italics me ya phrr unke neeche undeline honi chahiye

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Rahul Dagar 6 years, 2 months ago

Bhaii Homo sapiens genus aur species ka name haa

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Sohanveer Sharma 6 years, 2 months ago

Homosapiens

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What is the theory of (SPONTANEOUS GENERATION)

Posted by Rohit Yadav 6 years, 2 months ago

CBSE > Class 12 > Biology

1 answers

Muskaan Vig 6 years, 2 months ago

Theory of spontaneous generation says that every organism has evolved from non living matter like mud ,tree bark etc. This theory was made because a experiment was done in which rotten meat was put in an open jar and after a week the scientist found flies and its eggs around it and he said that non living materials are responsible for giving rise to living things. This theory was discarded by another experiment...

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what is aminosytsis

Posted by Free Fire Gamer 6 years, 2 months ago

CBSE > Class 12 > Biology

1 answers

Muskaan Vig 6 years, 2 months ago

Amniocentesis -technique of testing genetic disorder,chromosomal abnormalities ,fetal infections of foetus . Procedure: amniotic fluid surrounds baby in womb of mother that contains stem cells of baby and some of it is taken out for testing. Chromosomes are isolated from stem cells and arranged in definite order and are compared with other chromosomes which are correct in functioning. By this chromosome abnormalities can be found.

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Important topic of chapter 16 biology

Posted by Madhvi Rana 6 years, 2 months ago

CBSE > Class 12 > Biology

1 answers

Vivek Kumar 6 years, 2 months ago

You can get important notes contact me [email protected]

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Define Allen's rule.

Posted by Abhijeet Lol M 6 years, 2 months ago

CBSE > Class 12 > Biology

1 answers

Muskaan Vig 6 years, 2 months ago

Shorter the surface area ,less heat loss. Eg. People living in cold hilly areas have small ears so that heat loss is less..

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Diagram are important

Posted by Kajal Antil 6 years, 2 months ago

CBSE > Class 12 > Biology

3 answers

Sakshi Kaur ? 6 years, 2 months ago

Yes

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Ashish Tripathi 6 years, 2 months ago

Yes they are very important for bpth neet and boards

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Abhijeet Lol M 6 years, 2 months ago

Yes

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Why agrobacterium is a good cloning vector??

Posted by Anup Kumar 6 years, 2 months ago

CBSE > Class 12 > Biology

1 answers

Yogita Ingle 6 years, 2 months ago

Agrobacterium tumefaciens is used as a vector for plant transformation experiments. It is used to transfer gene of interest into the plant. It is a good vector-
1. Carry selectable marker such as antibiotic resistance gene for identifying the recombinants.
2. Small in size.
3. Carry origin of replication so that recombinant DNA molecule can multiply in the host cells.
4. Contain multiple restriction sites for restriction enzymes.
5. It contains a tumour inducing plasmid(ti plasmid) in dicots and has been modified into a cloning vector.

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Suggest investrigatory project for biology

Posted by Rishita Patel 6 years, 2 months ago

CBSE > Class 12 > Biology

1 answers

Taranveer Kaur 6 years, 2 months ago

Animal husbandry Plant breeding Microbes in human welfare Tunour Cancer Tuberculosis

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What is the scientific term used for the cyclic changes shown by seasonal breeders

Posted by Ajeeta Meena 6 years, 2 months ago

CBSE > Class 12 > Biology

1 answers

Muskaan Vig 6 years, 2 months ago

Oestrus cycle

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How can I understand the language of ncert

Posted by Anup Kumar 6 years, 2 months ago

CBSE > Class 12 > Biology

3 answers

Rahul Dagar 6 years, 2 months ago

No need to reed it for 3 to 4 times but read it only 2 times on first time read full NCERT and mark important points and on 2 nd time read only that imp points

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Anup Kumar 6 years, 2 months ago

Can I do so in February

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Ayush Madhu 6 years, 2 months ago

You should read whole ncert 3-5 times before final examination. Every time you have to read and learn your weak points. You will find something new each time.

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It is generally observed that the children who had suffered from chickenpox in their childhood may not contract in the same disease in their adulthood explain giving reason on the basic of such immunity in an individual name this kind of immunity

Posted by Sandy 14A 6 years, 2 months ago

CBSE > Class 12 > Biology

4 answers

Muskaan Vig 6 years, 2 months ago

And is acquired passive immunity..

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Muskaan Vig 6 years, 2 months ago

In Ist encounter with the pathogen our immune response is weak and is called primary response. During 2nd encounter with the same pathogen our body remembers that and produces intense immune response that kill the pathogen and is called secondary response.

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Rahul Dagar 6 years, 2 months ago

It is aquired immunity and memory b and t cells are produced that have intense response against the same antigen or pathogen . Secondary response is also called as anmestic response

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Vasu Sharma . 6 years, 2 months ago

This is the process in which our immune cells remember that which disease causing cells they were and after sometime if the disease causing cells again come in contact then our body has immunitive response to the cells if person is again affected then immunity of person is weak And immunity is passive in which weakend cells are taken to fight against cells

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Due to an error during transcription ATGof DNA formed UAG in mRNA. What would happen to polypeptide chain during translation by this changed mRNA

Posted by Ajeeta Meena 6 years, 2 months ago

CBSE > Class 12 > Biology