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Alenkinab [10]
3 years ago
10

True or False: Purine is connected to pyrimidine using oxygen bonds.​

Biology
1 answer:
valentina_108 [34]3 years ago
3 0

Answer:

False

Explanation:

In DNA double helix molecule, there are four types of nitrogenous bases: adenine, guanine, cytosine and thymine. Purines (i.e., adenine, guanine) and pyrimidines (i.e., cytosine and thymine) hold DNA strands together via hydrogen bonds. In base pairing, guanine always pairs with cytosine through 3 hydrogen bonds, while adenine always pairs with thymine by 2 hydrogen bonds. Hydrogen bonds are a type of dipole–dipole interaction where a hydrogen atom is covalently bonded to a very electronegative atom (e.g., Nitrogen or Oxygen).

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Four examples of the effects of environmental change are given. Match each one with the type of environmental change it demonstr
Vikki [24]

<u>Answer</u>: The answers are matched as follows:

African forests have been hunted to near extinction levels to obtain ivory-------------->human exploitation

The eruption of mount Saint Helens destroyed some populations of conifers------> natural disasters

An infection with a fungus reduced the population of North American Elm trees ----> disease

Increasing global temperatures have altered migration patterns of humpback whales ------>climate change

<u>Explanation</u>:

  • <em>Human</em> <em>exploitation</em> is the unethical or selfish use of resources to satisfy their own personal needs or for any profitable activity which harms the resources in such a way that they get limited. Humans have been hunting elephants to obtain ivory for many purposes such as making jewellery etc. and earning profits from it. Due to such extensive hunting they have driven the elephants to a level of extinction and thus, this is a form of human exploitation.
  • Mount Saint Helens is a volcano and its eruption which harms the population of the trees in the area is a form of natural disaster since volcanic eruption is a <em>natural</em> <em>phenomena</em>.
  • Fungal infection is a <em>disease</em> which is cause by the microorganisms which harms the population of the Elm trees.
  • Increase of global temperature is a type of climate <em>change</em> and thus, this effect of alteration of migration pattern is caused by climate change.
3 0
3 years ago
Explique de que forma a obstrução dos vasos da planta hospedeira pelos biofilmes de bactérias pode levar à morte progressiva das
musickatia [10]

Answer:

Os biofilmes são uma comunidade complexa de microrganismos, que pode ser composta por uma única espécie ou uma combinação de espécies. Os biofilmes são geralmente formados nas superfícies de materiais não vivos ou nos tecidos de organismos vivos; que pode estar externamente nos tecidos vivos dos organismos ou dentro dos tecidos vivos do organismo. Quando os microrganismos formam um biofilme, aumentam suas chances de resistir a anticorpos produzidos pelo organismo e aumentam suas chances de colonização completa do organismo. Algumas doenças são caracterizadas pela presença de biofilmes, que são, na maioria dos casos, a causa da doença.

<em>No caso de obstrução de vasos de plantas hospedeiras por biofilmes bacterianos; os biofilmes se formam na superfície do vaso e aumentam gradualmente de tamanho até que haja uma obstrução completa do vaso da planta. Quando o vaso da planta é eventualmente obstruído, o fluxo de materiais e minerais necessários é obstruído; levando à obstrução das células da raiz de receber materiais vitais e minerais necessários para o crescimento, isso eventualmente leva à morte progressiva das células da raiz.</em>

5 0
3 years ago
Suppose the volume of milk in a glass is 230 cubic cm. If 1 gallon of milk equals 3.79 liters, there are how many glasses of mil
balu736 [363]
Volume of milk that a glass can hold = 230 cubic cm
It is already given that
1 gallon of milk = 3.79 liters
W already know
1 liter = 1000 cubic cm
Then
3.79 liters = 1000 * 3.79 cubic cm
                = 3790 cubic cm
Now
Number of glasses needed to contain 230 cm^3 of milk = 1
So
<span>Number of glasses needed to contain 3790 cm^3 of milk = 3790/230
</span>                                                                                           = 16.48
From the above deduction, we can conclude that 17 glasses of milk are required to hold 1 gallon of milk.
4 0
3 years ago
Who discovered that dna was the genetic material or transforming factor that could convert nonvirulent r-type streptococcus pneu
KatRina [158]
Discovery
               In 1928 it was discovered by Frederick Griffith in an experiment generally known as transformation.

Experiment
                 
 In his experiment he considered two strains of <em>streptococus pneumonia,</em> one was R-type which was non-virulent and cause no disease in mice, other was virulent and S-type which cause disease and at last death of mice.
This experiment was comprised of four steps which are as follow:

 Step 1:
           First he injected living strain of S into mice, after sometime mouce died.

Step 2:
          He injected living strain of R into mice, the mice alive as he did not got any disease.

Step 3:
         He injected heat killed strain of S into mice and mice remain alive.

Step 4:
           He mixed living R strain with heat killed S strain and then inject into mice. As a result the mice died.

Conclusion:
                  It was found that genetic material from heat killed S stain were transferred to living R (non-virulent) strain, as a result R become virulent and cause the death of mice.

7 0
2 years ago
Please help me if your answer is fast you can have BRAINLIEST
stiv31 [10]

Answer:

40 ft may be not sure . .......

3 0
3 years ago
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