When double-stranded DNA is heated at neutral pH, which change does not occur? A) The absorption of ultraviolet (260 nm) light increases.
B) The covalent N-glycosidic bond between the base and the pentose breaks.
C) The helical structure unwinds.
D) The hydrogen bonds between A and T break.
E) The viscosity of the solution decreases.

Answers

Answer 1
Answer:

Answer:

B) The covalent N-glycosidic bond between the base and the pentose breaks

Explanation:

When forces that bind 2 DNA strands are broken, these strands finally split. This process is called denaturalization

The main forces that remain both DNA strands together are the hydrogen bonds (physical forces), between pair of bases (Adenine with Thymine, and Guanine with Cytosine)

Denaturalization may occur by different factor: Ph alteration, salt addition, temperature (heating), etc

When heating a DNA solution, denaturalization process may be followed using UV absorption (normally, at wavelength of 260 nm): when DNA (double strand) has its regular structure, UV light absorption is low, as the nitrogen bases are stacked like a pile of coins, for which structure absorbs less light

When DNA structure is denaturalized, these nitrogen bases are exposed, and UV absorption increases

Also, DNA denaturalization may be followed by viscosity: for a double strand DNA solution, viscosity is high due to double chain stiffness but when strands are denaturalized, simple strands solution are less viscous (so viscosity decreases over time, when heating the solution)

Lastly, when solution is heated, only physical forces are broken (hydrogen bonds) and not chemical bonds (such as covalent bonds), for which extreme conditions are needed


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How many moles of calcium chloride would be produced by the reaction below when 53.2 milliliters of water are produced, if the density of water is 0.987 g/mL? Show all steps of your calculations as well as the final answer HCl + Ca(OH) 2 → H2O + CaCl2

Which of the following has the greatest number of atoms? a) 1.0 mol He b) 0.60 mol H2 c) 20 g Potassium d) 8.5 mL H2O (density of H2O = 1 g/mL) e) 22.6 g KMnO4

Answers

Answer:

The H2O sample has the greatest number of atoms.  1.41 moles, or (1.041 moles)*(5.023x10^23) atoms

Explanation:

We need to convert each value into moles, a count of the number of atoms/molecules.

a)  1.0 moles He

b)  0.60 moles H2

c)  20 grams K:  convert to moles with the molar mass of K

                       (20 grams K)/(39.1 g/mole K) = 0.511 moles K

d) 8.5 mL H2O (density of H2O = 1 g/mL).

      Find the mass of the H2):  (8.5 ml)*(1 g/ml) = 8.5 grams H2)

      Now calculate moles H2):  (8.5 grams)/(18 grams/mole) = 0.473 moles     H2O

e)  22.6 g KMnO4  

                    (22.6 g KMnO4 )*(158.0 g/mole) = 0.143 moles

Now we need to take into account the number of atoms per molecule:

Molecule  Atoms/Molecule     Moles        Atoms(moles)

He                     1                            1.0               1.0

H2                     2                           0.60            1.2

K                        1                            0.51            0.51

H2O                  3                            0.47            1.41

KMnO4             6                            0.143          0.86

The H2O sample has the greatest number of atoms.  1.41 moles, or (1.041 moles)*(5.023x10^23) atoms

Which solution when mixed with a drop of bromthymol blue will cause the indicator to change from blue to yellow 1) 0.1 M HCl. 2) 0.1 M CH3OH. 3) 0.1 M NH3. 4) 0.1 M NaOH

Answers

The solution that when mixed with a drop of bromthymol blue will change the indicator to yellow is A. 0.1 M HCl.

What is an indicator?

An indicator simply means a substance that has measurable and observable characteristics that is important to depict an acidic or alkaline substance.

In this case, the solution that when mixed with a drop of bromthymol blue will change the indicator to yellow is 0.1 M HCl.

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1) is the answer because the only way to turn it from blue to yellow is to mix it with an acidic solution. 

Smoking marijuana can be as unhealthy as smoking cigarettes and ___________a. can cause cancer.
b. results in "smokers breath."
c. can lead to premature aging.

Answers

The answer is all of them. But in a school situation, would be appropriate. This is because the smoke gets into the smokers lungs, whether it be marijuana or tobacco, and can cause cancer cells to grow in your lungs and enter your bloodstream.
So A is the answer. 

Smoking marijuana can be as unhealthy as smoking cigarettes and can cause cancer.

a. can cause cancer.

Smoking marijuana can be as unhealthy as smoking cigarettes, and it can cause cancer. Marijuana smoke contains many of the same harmful chemicals as cigarette smoke, including tar, carbon monoxide, and carcinogens. These chemicals can damage DNA and lead to the development of cancer.

In addition to cancer, smoking marijuana can also lead to other health problems, such as respiratory problems, heart disease, and lung infections. It can also impair cognitive function and increase the risk of accidents.

The other options, b. results in "smokers breath" and c. can lead to premature aging, are also possible effects of smoking marijuana, but they are not as serious as cancer.

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Describe 3 ways that you could change the rate of the reaction based on principles that effect rates of reactions.

Answers

Three ways to change the rate of a reaction are by increasing the concentration of reactants, changing the temperature, and adding a catalyst.

Three ways to change the rate of a reaction:

  1. Increasing the concentration of reactants: This increases the collision frequency between particles, leading to a higher reaction rate. For example, in the reaction between hydrogen and iodine to form hydrogen iodide, increasing the concentration of hydrogen and iodine will speed up the reaction.
  2. Changing the temperature: Higher temperatures increase the kinetic energy of particles, making them move faster and collide more frequently. This results in a faster reaction rate. Using an example, raising the temperature of the reaction between magnesium and hydrochloric acid will speed up the rate of reaction.
  3. Adding a catalyst: Catalysts are substances that speed up reactions by providing an alternative reaction pathway with lower activation energy. For instance, adding an enzyme catalyst like amylase to the reaction between starch and iodine will increase the reaction rate.

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The three main ways to change the rate of reaction based on principles that affect rates of reactions are concentration, temperature, and catalysts .let us describe them one by one further.

Three ways to change the rate of a chemical reaction are:

  • Concentration Change: Increasing the concentration of reactants usually speeds up the reaction. This is due to more frequent collisions between particles, increasing the likelihood of successful collisions leading to product formation.
  • Temperature Change: Raising the temperature accelerates reactions by providing more energy to reactant particles, increasing their kinetic energy, and promoting successful collisions.
  • Catalysts: Adding a catalyst lowers the activation energy required for the reaction, making it easier for reactants to transform into products. Catalysts provide an alternate reaction pathway, allowing reactions to occur at lower energy levels and faster rates.

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The ________ is the balance of the amount of carbon in each reservoir.a. global nitrogen budget
b. global carbon budget
c. global oxygen budget
d. global respiration budget

Answers

Answer: Global carbon budget.

Explanation: The global carbon budget can be defined as the budget that balances the fluxes of carbon between the four reservoirs. These four reservoir of carbon are Earth's terrestrial biosphere, hydrosphere, atmosphere and geosphere.

The total amount of carbon on the earth should be maintained so there is a global carbon budget that maintains the amount of carbon on earth.

the answer is b. global carbon budget

Consider the two facts below:Fact 1: Dissolved oxygen is one of the most
important nutrients needed by fish in the aquatic
environment to survive.
Which scenarios may be explained by the facts on
the left? Check all that apply.
ID There is more dissolved oxygen in colder
waters than in warm water.
IM
Fact 2: Unlike solids, whose solubility increases
with increasing temperature, the solubility of gases
generally decreases with increasing temperature.
IND
There is less dissolved oxygen in colder
waters than in warm water.
Fish life in the ocean is more abundant during
the seaons with warmer water than seasons
with cooler water
HII
If ocean temperatures rise, then the risk to
the fish population increases.
DONE W

Answers

Answer:

A. There is more dissolved oxygen in colder waters than in warm water.

D. If ocean temperature rise, then the risk to the fish population increases.

Explanation:

Conclusion that can be drawn from the two facts stated above:

*Dissolved oxygen is essential nutrient for fish survival in their aquatic habitat.

*Dissolved oxygen would decrease as the temperature of aquatic habit rises, and vice versa.

*Fishes, therefore, would thrive best in colder waters than warmer waters.

The following are scenarios that can be explained by the facts given and conclusions arrived:

A. There is more dissolved oxygen in colder waters than in warm water (solubility of gases decreases with increase in temperature)

D. If ocean temperature rise, then the risk to the fish population increases (fishes will thrive best in colder waters where dissolved oxygen is readily available).

Answer: the answers are A and D

Explanation:

i got it right