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The Miller-Urey experiment was an experiment that simulated hypothetical conditions present on the early Earth in order to test what kind of environment would be needed to allow life to begin. The experiment is considered to be the classic experiment on the origin of life. It was conducted in 1953 by Stanley L. Miller and Harold C. Urey at the University of Chicago. The experiment used water (H2O), methane (CH4), ammonia (NH3) and hydrogen (H2) - materials which were believed to represent the major components of the early Earth's atmosphere. The chemicals were all sealed and circulated inside a sterile array of glass tubes and flasks connected together in a loop, with one flask half-full of liquid water and another flask containing a pair of electrodes. The liquid water was heated to add water vapour to the chemical mixture and the resulting gases were circulated around the apparatus, simulating the Earth's atmosphere. The flask with heated water represents water on the Earth's surface and the recycled water vapor is just as water evaporates from lakes and seas, before going into the atmosphere and forming into rain. Sparks were fired between the electrodes to simulate lightning storms (believed to be common on the early earth) through the water vapors, and then the vapors were cooled again so that the water could condense (simulating the oceans) and trickle back into the first water flask in a continuous cycle. At the end of one week of continuous operation, Miller and Urey observed, by analyzing the cooled water, that as much as 10-15% of the carbon within the system was now in the form of organic compounds. Two percent of the carbon had formed amino acids, including 13 of the 22 that are used to make proteins in living cells, with glycine as the most abundant. The molecules produced were simple organic molecules, far from a complete living biochemical system, but the experiment established that the hypothetical processes could produce some building blocks of life without requiring life to synthesize them first.

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Name the type of cross that would help to find genotype

Posted by Sethu Prabhul 6 years, 1 month ago

CBSE > Class 12 > Biology

5 answers

Aleena Elizabeth Vinod 6 years, 1 month ago

Test Cross

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Ayush Ahlawat 6 years, 1 month ago

Test cross( best)

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Muskaan Vig 6 years, 1 month ago

Test Cross..cross done between homozygous recessive and individual whose genotype is to be found....its genotype is determined on basis of progeny ratio........

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Vishal Bhilavekar 6 years, 1 month ago

Test cross

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Yogita Ingle 6 years, 1 month ago

The genotype of a pea plant bearing violet flowers is test cross.

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Example of offset

Posted by Bablu Yuvraj 6 years, 1 month ago

CBSE > Class 12 > Biology

2 answers

Prashant Kumar 6 years, 1 month ago

Pistia ,eichhornia

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Muskaan Vig 6 years, 1 month ago

Water Hyacinth (Eicchornia Crassipes)

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Is colstrum is a passive or active immunity?

Posted by Jatin Khatri 6 years, 1 month ago

CBSE > Class 12 > Biology

2 answers

Aleena Elizabeth Vinod 6 years, 1 month ago

Passive immunity

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Ďãřşháñăã Yadav ? ? ? 6 years, 1 month ago

colostrum is passive immunity

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4. A biotechnologist wanted to create a colony of E.coli possessing the plasmid pBR322, sensitive to Tetracycline. Which one of the following restriction sites would he use to ligate a foreign DNA?

Posted by Srishti Karn 6 years, 1 month ago

CBSE > Class 12 > Biology

2 answers

Aleena Elizabeth Vinod 6 years, 1 month ago

Sal l

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Yogita Ingle 6 years, 1 month ago

The biotechnologist can ligate the foreign DNA at the Sal I of Tetracycline resistance gene in pBR322 vector.

• Since the Tetracycline resistance gene has 2 restriction sites, namely BamH I and Sal I, the foreign DNA can be ligated at any of these 2 sites.

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Antibodies present in colustrum which protect new born from certain disease

Posted by Padmaja Maurya 6 years, 1 month ago

CBSE > Class 12 > Biology

5 answers

Aleena Elizabeth Vinod 6 years, 1 month ago

IgA

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Srishti Karn 6 years, 1 month ago

IgA

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Yogita Ingle 6 years, 1 month ago

The yellowish fluid colostrum is secreted by mother during the initial days of lactation has abundant antibodies (IgA) to protect the infant from several diseases. IgG immunoglobulin (antibody) is most abundant (appro .80%) antibody in human and found in serum IgA is second abundant (approx .10-15%) antibody. It is found in saliva and tear also. IgD and IgE constitute 2-3% of total antibodies which are found in most cells and serum.

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Licy Mathew V 6 years, 1 month ago

IgA

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Khushi Arora 6 years, 1 month ago

IgE

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Differentiate between dominance and co dominances

Posted by Faiz Ibrahim 6 years, 1 month ago

CBSE > Class 12 > Biology

2 answers

Yogita Ingle 6 years, 1 month ago

<th>Basis for Comparison</th> <th>Incomplete Dominance</th> <th>Co-Dominance</th>

Meaning	The condition when neither of the alleles is dominant, rather combine and display a new trait by mixing of the two alleles is called as Incomplete Dominance.	The condition when both the alleles of a gene are dominant, and the traits are equally expressed, called as Co-Dominance.
Dominancy	Neither of both the allele is dominant and give a new trait.	Both the alleles are fully dominant.
Example	Snapdragon, Mirabilis Jalapa.	Roan character in cattle, A and B blood group in human.
Effect	Though both the allele blend their effect, one of the two is more noticeable.	Here both the alleles equally blend and show their equal effects.

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Khushi Arora 6 years, 1 month ago

dominance-when only one type of the genes complete represents its character while other one does not represent its character at all and the dominant one's character is seen. co-dominance-when both the genes i.e. from both parents for same type of character represent their character and their result is different from exactly both the parents.

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Study and write about the flowers adapted to pollination by insect

Posted by Aanchal Shagufta 6 years, 1 month ago

CBSE > Class 12 > Biology

1 answers

Saurabh Ķům-Ŕ 6 years, 1 month ago

https://study.com/academy/lesson/insect-pollination-process-diagram-adaptations.html

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Carefully examine structure A and B of pentose sugar given below. Which one of the two is more reactive ? Give reasons

Posted by Debanjana Sinha 6 years, 1 month ago

CBSE > Class 12 > Biology

1 answers

Muskaan Vig 6 years, 1 month ago

A-Ribose sugar because of presence of OH group at everynucleotide at 2'position

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Study kese rhe ab

Posted by Brajmohan Yadav 6 years, 1 month ago

CBSE > Class 12 > Biology

0 answers

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What is acute diseases

Posted by Mayank Choudhary 6 years, 1 month ago

CBSE > Class 12 > Biology

2 answers

Muskaan Vig 6 years, 1 month ago

The disease remians for short period of time and not life longing.Sometimes the person don't even require any medical help.eg..common cold, pneumonia etc

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Brajmohan Yadav 6 years, 1 month ago

After the birth

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Outbreeding devices

Posted by Neha Yadav 6 years, 1 month ago

CBSE > Class 12 > Biology

3 answers

Vaishnavi Pachapur 6 years, 1 month ago

Outbreeding devices are mechanisms which are followed and adapted by the plants in order to prevent self pollination. The examples of outbreeding devices are: ... Hetrostyly: The anther and stigma are present at different levels of the flower which prevents the self pollination and fertilization.

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Anil Yadav 6 years, 1 month ago

Condom

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Shivam Singhania 6 years, 1 month ago

Condoms. Copper t

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Does AUG code for methionine in prokaryotes as well as eukaryotes?

Posted by Kalpana Jha 6 years, 1 month ago

CBSE > Class 12 > Biology

2 answers

Manika Gupta 6 years, 1 month ago

All codes are universal in nature except some

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Muskaan Vig 6 years, 1 month ago

AUG codes for 'methionine' in eukaryotes and 'formyl methionine' in prokaryotes.

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Who gave the law of natural selection????

Posted by Monika Paswan 6 years, 1 month ago

CBSE > Class 12 > Biology

2 answers

Yogita Ingle 6 years, 1 month ago

Carles Darwin is known as the father of evolution due to his contribution to the establishment of the theory of evolution. His theory helped in removing all the conventional old believes which said that the formation of various species was a supernatural phenomenon or act of the Almighty. Darwin’s evolutionary theory of natural selection gave a more rational explanation of the formation of new species. As per natural selection, various species originated from a single species as a result of adaptation to the changing environment.

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Muskaan Vig 6 years, 1 month ago

Charles Darwin...

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name the stds which can be transfer through contaminated blood?

Posted by Koshal Sharma 6 years, 1 month ago

CBSE > Class 12 > Biology

1 answers

Muskaan Vig 6 years, 1 month ago

AIDS(Acquired Immuno Deficiency Syndrome)

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Viva questions of bio.????

Posted by Kriti Sharma 6 years, 1 month ago

CBSE > Class 12 > Biology

1 answers

Monika Paswan 6 years, 1 month ago

Ha jo aapko aapke biology teachers batae ki kon sa experiment aaega to usi ka questions yaad kar lo aur jo yaad nhi hote ushe bss dekh lo... ok

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Why the productivity of ocean is less

Posted by Tanvi Choudhary 6 years, 1 month ago

CBSE > Class 12 > Biology

1 answers

Yogita Ingle 6 years, 1 month ago

Oceans are least productive because:
(i) There is insufficient radiation as sunlight decreases with the increasing depth of the ocean.
(ii) Oceans are nitrogen deficient which is an important nutrient for plants.
(iii) Conditions of high salinity in ocean are not favourable for all plants.
(iv) There is no substratum to support plants.

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Discribe 3 method of solid waste

Posted by Gungnao Thongam 6 years, 1 month ago

CBSE > Class 12 > Biology

1 answers

Meghna Thapar 6 years, 1 month ago

Methods of Solid Waste Disposal and Management: 1. Solid Waste Open Burning Solid waste open burning is not the perfect method in the present scenario. 2. Sea Dumping Process This sea dumping process can be carried out only in coastal cities. This is very costly procedure and not environment friendly. 3. Solid wastes sanitary landfills Solid wastes sanitary landfills process is simple, clean and effective. In this procedure, layers are compressed with some mechanical equipment and covered with earth, leveled, and compacted. A deep trench of 3 to 5 m is excavated and micro-organisms act on the organic matter and degrade them. In this procedure, refuse depth is generally limited to 2m. Facultative bacteria hydrolyze complex organic matter into simpler water soluble organics 4. Incineration method Incineration method is suitable for combustible refuse. High operation costs and construction are involved in this procedure. This method would be suited in crowded cities where sites for land filling are not available. It can be used to reduce the volume of solid wastes for land filling. 5. Composting process Composting process is similar to sanitary land-filling and it is popular in developing countries. Decomposable organic matter is separated and composted in this procedure. Yields are stable end products and good soil conditioners. They can be used as a base for fertilizers. Two methods have been used in this process: a)Open Window Composting b) Mechanical Composting

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Name the restriction endonuclease enzyme that recognise the palindrome. How does it function

Posted by Nisha Nayak 6 years, 1 month ago

CBSE > Class 12 > Biology

1 answers

Meghna Thapar 6 years, 1 month ago

A restriction enzyme, restriction endonuclease, or restrictase is an enzyme that cleaves DNA into fragments at or near specific recognition sites within molecules known as restriction sites. Restriction enzymes cut double-stranded DNA* at specific locations based the pattern of bases found at those locations. These enzymes predictably cut both strands because the sequences they recognize are palindromic. That is the recognition sequences are short string of identical bases on both DNA strands.As a set of paired sequences (one on each of the strands of a double strand of DNA), the palindromes recognized by restriction enzymes follow a slightly different set of rules. They are probably more properly referred to as palindromic sequences to distinguish them from language palindromes. Palindromic sequences are a short run of bases (typically 3 to 5 in length), follow by their complementary bases in reverse order. For example the recognition sequence for BamHI is GGATCC. The first three bases GGA are followed by the complement of those three bases in reverse order: TCC. The complement to the whole six base strand is CCTAGG, read backwards (as it would be when reading from 5’ to 3’ on the complementary strand) is GGATCC, an exact match for the original strand.

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What is the role of selectable marker in a cloning vector?

Posted by Arun Kumar 6 years, 1 month ago

CBSE > Class 12 > Biology

1 answers

Yogita Ingle 6 years, 1 month ago

Selectable markers are essential to identify and eliminate non-transformants(no recombinant DNA), and selectively permitting the growth of the transformants (host cells bearing recombinant DNA).

Selectable marker-

It helps in identifying and eliminating non transformants and selectively permitting the growth of the transformants.
Transformation is a procedure through which a piece of DNA is introduced in a host bacterium.
The genes encoding resistance to antibiotics such as ampicillin, chloramphenicol, tetracycline or kanamycin, etc., are useful selectable markers for E. coli as the normal E. coli cells do not carry resistance against any of these antibiotics.
Antibiotic resistance genes help in selecting recombinants from non-recombinants by a method called insertional inactivation where a recombinant DNA is inserted within the coding sequence of an enzyme β-galactosidase in the presence of a chromogenic substrate which results into inactivation of the enzyme.
The presence of a chromogenic substrate gives blue colored colonies if the plasmid in the bacteria does not have an insert.
Presence of insert results into insertional inactivation of the β-galactosidase and the colonies do not produce any colour, these are identified as recombinant colonies.

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What is reprduction

Posted by Ankitkumar Panday 6 years, 2 months ago

CBSE > Class 12 > Biology

1 answers

Princy Pandey 6 years, 1 month ago

Reproduction is defined as a biological process in which an organism gives rise to young ones (offspring) similar to itself.

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What is the difference between parthenogenesis and parthenocarpy?

Posted by Surbhi Purway 6 years, 2 months ago

CBSE > Class 12 > Biology

3 answers

Yogita Ingle 6 years, 1 month ago

In most plants, flowers need to be pollinated and fertilized to produce fruits. However, some plants can produce fruits before fertilization or without fertilization. Parthenocarpy is the process which produces fruits from unfertilized ovules in plants. Unfertilized ovules develop into fruits prior to fertilization. These fruits do not contain seeds.
Parthenogenesis is a type of reproduction commonly shown in organisms mainly by some invertebrates and lower plants. It can be described as a process in which unfertilized ovum develops into an individual (virgin birth) without fertilization. Therefore, it can be considered as a method of asexual reproduction.
It is seen in organisms like rotifers, honeybees and even some lizards and birds (turkey). The key difference between parthenogenesis and parthenocarpy is, parthenogenesis is shown by animals and plants while pathenocarpy is shown only by plants.

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Muskaan Vig 6 years, 1 month ago

Parthenogenesis-Development of egg of female into organism without fertilization.Eg.male bees(drones) are produced by this process.......... ____Parthenocarpy-development of fruit from ovary without fertilization of ovule........These fruits are seedless.Eg.banana

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Praval Gautam 6 years, 2 months ago

5uo

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Is someone's final practical is complete then can you tell what questions is asked from you

Posted by Rajesh Bhadkare 6 years, 2 months ago

CBSE > Class 12 > Biology

1 answers

Monika Paswan 6 years, 1 month ago

Mere maths ke practicle mein mujhse sirf intigration k formulae pooche gye

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How does gain or loss of chromosome(s) takes place in humans? Describe one example each of chromosomal disorder along with the symptoms involving an autosome and a *** chromosome.

Posted by Aradhya Singh 6 years, 2 months ago

CBSE > Class 12 > Biology

1 answers

Jd Chouhan 6 years, 2 months ago

Aneuploidy

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Sir/ Mam i am not able to understand the pedigree analysis of chapter 6 plz taught me

Posted by Atul Vinayak Singh 6 years, 2 months ago

CBSE > Class 12 > Biology

3 answers

Sam Raza 6 years, 1 month ago

*** linked dominant

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Aman Raza 6 years, 2 months ago

It is the way to study the inheritance in humans in several generations

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Sinchana Malagond 6 years, 2 months ago

Which part are you not understanding?? Like to identity which is autosomal dominant or recessive.*** linked dominant or recessive??? Kindly inform so that I can help you.

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To identify study and comment on stages of oogenesis from T.S. of ovary

Posted by Roshan Kumar 6 years, 2 months ago

CBSE > Class 12 > Biology

1 answers

Meghna Thapar 6 years, 1 month ago

T.S. of Ovary: (i) In the section of ovary, there is a mass of tissue lined with germinal epithelium. Observe an ovum, which is a cell surrounded by one to several layers of follicular cells. As the ovum matures, the number of surrounding follicular cell layer increases. (ii) In the later stage of folliculardevelopment a cavity called antrum appears. (iii) The cavity gets further enlarged and the follicle grows bigger. This is the stage of Graafian follicle ready to release the ovum (ovulation). (iv) In the next stage, you may notice a Corpus luteum, and/or Corpus albicans, which differ from each other and also from Graafian follicle in their features.

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Cbse practicle paper

Posted by Jaishree Gidwan 6 years, 2 months ago

CBSE > Class 12 > Biology

0 answers

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What is linkage and recombination?

Posted by Ananya Paul 6 years, 2 months ago

CBSE > Class 12 > Biology

2 answers

Aastha Saxena 6 years, 2 months ago

Simply the linkage is the physical associations of genes on a chromosome and recombination describes the generation of non parental gene combinations.

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Yogita Ingle 6 years, 2 months ago

“Linkage and recombination are the phenomena that describe the inheritance of genes.”

Linkage

Morgan noted that while crossing a set of characters, two genes did not follow Mendel’s law as they did not divide as per the law. The likelihood of achieving a parental combination if two genes are situated on the same chromosome was relatively higher in the subsequent generation in comparison to the non-parental combination. The physical connection of genes was referred to as linkage.

Recombination

Recombination is a process of producing new combinations of alleles by the recombination of DNA molecules. It is also referred to as genetic recombination, as there is an exchange of genetic material(DNA) between two different chromosomes or between different regions of the same chromosome. This process is observed in both eukaryotes and prokaryotes. It increases the genetic diversity of sexually reproducing organisms.

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