Ask questions which are clear, concise and easy to understand.
Ask QuestionPosted by Risky Gilhotra 6 years, 9 months ago
- 2 answers
Yogita Ingle 6 years, 9 months ago
Atmospheric ozone is measured by various methods and also by using various instruments. Ozone is measured in Dobson units (DU).
Different types of measurements used to measure ozone in the atmosphere are ground based measurements, air-borne measurements and satellite measurements.
*Dobson spectrophotometer is the earliest instrument used to measure both column ozone and profiles of ozone in the atmosphere.
*LIDAR ( Light Detection and Ranging ) is a technique used to measure ozone. This depends on absorption of laser light by ozone.
*Ozonesonde includes a ballon carrying the instrument upto 21 miles high into stratosphere to measure ozone.
*Rockets are used to measure level at an altitude of 75 km.
*Satellites are used to measure the ozone over the entire globe. e.g. TOMS is one such aid to measure ozone.
Sayeda Iram Ateeq 6 years, 9 months ago
Posted by Risky Gilhotra 6 years, 9 months ago
- 1 answers
Posted by Jayant Tehlan 6 years, 9 months ago
- 1 answers
Gaurav Seth 6 years, 9 months ago
Hidden hunger means the deficiency of micronutrients due to low intake of vitamins and minerals. The effects of the deficiency are not visible and the person may seem alright thus it is called hidden hunger.
Posted by Indian Akash 6 years, 9 months ago
- 1 answers
Meghna Thapar 5 years, 5 months ago
The Bryophylum leaf has many buds grown on its margin of the leaf so when it falls down in moist soil it grows up into new individual plant.
The epiphylous buds of leaves of Bryophyllum are modified to perform the function of vegetative propagation.
As the buds are capable of producing offspring by vegetative propagation. New plants arise when cut pieces of Bryophyllum leaves are kept in wet soil.
Posted by Lokesh Ramadas 6 years, 9 months ago
- 1 answers
Posted by Aryaman Singh Tomar 6 years, 9 months ago
- 2 answers
Mohd Aamash 6 years, 9 months ago
Posted by Yudhvir Singh 6 years, 9 months ago
- 1 answers
Simran Rana 6 years, 9 months ago
Posted by Parmjit Kaur 6 years, 9 months ago
- 4 answers
Aishwarya S 6 years, 9 months ago
Posted by Archit Sheokand 6 years, 9 months ago
- 1 answers
Gaurav Seth 6 years, 9 months ago
Autecology deals with the biological relationship between an individual organism or an individual species and its environment.
Posted by A Jaiswal 6 years, 9 months ago
- 3 answers
Gajendra Singh Rajput 6 years, 9 months ago
Posted by Zameel Akhtar 6 years, 9 months ago
- 1 answers
Posted by Mohd Aamash 6 years, 9 months ago
- 1 answers
Thansy Zakeer 6 years, 9 months ago
Posted by Bittu Tomar 6 years, 9 months ago
- 1 answers
Meghna Thapar 5 years, 5 months ago
The tendency for genes to be inherited together as a package because of their location near one another on the same chromosome. Linkage is the phenomenon of certain genes staying together during inheritance through generations without any change or separation due to their being present on the same chromosome. All those genes which are located in the single chromosome form one linkage group. The total number of linkage group in an organism corresponds to the number of chromosome pairs. For example, there are 23 linkage groups in man, 7 in sweet pea and 4 in Drosophila melanogaster.
Posted by Nidhi Chauhan 6 years, 9 months ago
- 3 answers
Gautãm . 6 years, 9 months ago
Posted by Ankit Kumar 6 years, 9 months ago
- 1 answers
Posted by Anurag Saikia 6 years, 9 months ago
- 1 answers
Posted by Tanu Singh 6 years, 9 months ago
- 1 answers
Adithyan Karthik 6 years, 9 months ago
Posted by Vishal Kumar Jaiswal 6 years, 9 months ago
- 1 answers
Posted by Gyanson Wahengbam 6 years, 9 months ago
- 1 answers
Simran Rana 6 years, 9 months ago
Posted by Gyanson Wahengbam 6 years, 9 months ago
- 5 answers
Bharti Devnani 6 years, 9 months ago
Posted by Gyanson Wahengbam 6 years, 9 months ago
- 1 answers
Posted by Supriya Singh 2 years, 4 months ago
- 3 answers
Simran Rana 6 years, 9 months ago
A Jaiswal 2 years, 4 months ago
Posted by Gyanson Wahengbam 6 years, 9 months ago
- 1 answers
Posted by Mukesh Kumar 6 years, 9 months ago
- 1 answers
Posted by Sahil Singh 6 years, 9 months ago
- 2 answers
Posted by Gyanson Wahengbam 6 years, 9 months ago
- 1 answers
Baahubali ??????? 6 years, 9 months ago
Posted by Simran Rana 6 years, 9 months ago
- 2 answers
Adithyan Karthik 6 years, 9 months ago
Posted by Preetibardhan Panda 6 years, 9 months ago
- 3 answers
Yogita Ingle 6 years, 9 months ago
The two scientists that proove DNA is the genetic material are:
(i) Griffith Transformation Experiment
(a) In 1928, Frederick Griffith, in a series of experiments with Streptococcus pneumoniae (bacterium responsible for pneumonia), witnessed a miraculous transformation in the bacteria.
(b) When Streptococcus pneumoniae (pneumococcus) bacteria are grown on a culture plate, some produce smooth shiny colonies (S) while others produce rough colonies (R). This is because the S strain bacteria have a mucous (polysaccharide) coat, while R strain does not. Mice infected with the S strain (virulent) die from pneumonia infection but mice infected with the R strain do not develop pneumonia.
S strain ---> Inject into mice ----> Mice die
R strain ----> Inject into mice ----> Mice live
Griffith was able to kill bacteria by heating them. He observed that heatkilled S strain bacteria injected into mice did not kill them.
S strain (heat-killed) ----> Inject into mice ----> Mice live
When he injected a mixture of heat-killed S and live R bacteria, the mice died.
S strain (heat-killed) + R strain (live) ----> Inject into mice ----> Mice die
Moreover, he recovered living S bacteria from the dead mice.
(c) He concluded that the R strain bacteria had somehow been transformed by the heat-killed S strain bacteria. Some ‘transforming principle’, transferred from the heat-killed S strain, had enabled the R strain to synthesise a smooth polysaccharide coat and become virulent. This must be due to the transfer of the genetic material.
(d) Prior to the work of Oswald Avery, Colin MacLeod and Maclyn McCarty (1933-44), the genetic material was thought to be a protein. They worked to determine the biochemical nature of ‘transforming principle’ in Griffith’s experiment.
(e) They purified biochemicals (proteins, DNA, RNA, etc.) from the heat-killed S cells to see which ones could transform live R cells into S cells. They discovered that DNA alone from S bacteria caused R bacteria to become transformed.
(f) They also discovered that protein-digesting enzymes (proteases) and RNAdigesting enzymes (RNases) did not affect transformation, so the transforming substance was not a protein or RNA. Digestion with DNase did inhibit transformation, suggesting that the DNA caused the transformation. They concluded that DNA is the hereditary material.
(ii) Hershey and Chase Experiment
(a) DNA is the genetic material came from the experiments of Alfred Hershey and Martha Chase (1952). They worked with viruses that infect bacteria called bacteriophages.
(b) The bacteriophage attaches to the bacteria and its genetic material then enters the bacterial cell. The bacterial cell treats the viral genetic material as if it was its own and subsequently manufactures more virus particles. Hershey and Chase worked to discover whether it was protein or DNA from the viruses that entered the bacteria.
(c) They grew some viruses on a medium that contained radioactive phosphorus and some others on medium that contained radioactive sulfur. Viruses grown in the presence of radioactive phosphorus contained radioactive DNA but not radioactive protein because DNA contains phosphorus but protein does not. Similarly, viruses grown on radioactive sulfur contained radioactive protein but not radioactive DNA because DNA does not contain sulfur.
(d) Radioactive phages were allowed to attach to E. coli bacteria. Then, as the infection proceeded, the viral coats were removed from the bacteria by agitating them in a blender. The virus particles were separated from the bacteria by spinning them in a centrifuge.
(e) Bacteria which was infected with viruses that had radioactive DNA were radioactive, indicating that DNA was the material that passed from the virus to the bacteria. Bacteria that were infected with viruses that had radioactive proteins were not radioactive. This indicates that proteins did not enter the bacteria from the viruses. DNA is therefore the genetic material that is passed from virus to bacteria.
myCBSEguide
Trusted by 1 Crore+ Students
Test Generator
Create papers online. It's FREE.
CUET Mock Tests
75,000+ questions to practice only on myCBSEguide app
Sayeda Iram Ateeq 6 years, 9 months ago
2Thank You