Tag: zoology

Questions Related to zoology

In the stratosphere, what does screen out a large fraction of the ultraviolet rays of the sun?

zoology allotropy of oxygen ozone - a case study stratospheric pollution ozone and its depletion

  1. $H _2$

  2. $SO _2$

  3. $CO$

  4. $HCl$

  5. $O _3$

Show answer
Correct Option: E
Explanation:

In the stratosphere, ozone $\displaystyle O _3 $ screen out a large fraction of the ultraviolet rays of the sun. Thus, ozone acts as a protective shield. Thus, due to presence of ozone layer, the harmful ultraviolet rays cannot penetrate earth's atmosphere. Hence, they cannot reach us.

Ozone deplete due to the formation of following compound in antartica?

zoology allotropy of oxygen ozone - a case study stratospheric pollution ozone and its depletion

  1. Acrolein

  2. peroxy acetyl nitrate

  3. $SO _2$ and $SO _3$

  4. Chlorine nitrate

Show answer
Correct Option: D
Explanation:

The ozone depletion was related to halogen (chlorine)-catalyzed chemical reaction which takes place in the spring season in the Antarctic polar region. The chlorine is derived from manmade chlorofluorocarbons and reacts with nitric acid forms chlorine nitrate($ClONO _2$) (CFCs) in the stratosphere.

Hence option D is correct. 

The two forms of oxygen found in the atmosphere are:

zoology allotropy of oxygen ozone - a case study stratospheric pollution ozone and its depletion

  1. Water and ozone

  2. Water and oxygen

  3. Ozone and oxygen

  4. Water and carbon-dioxide

Show answer
Correct Option: C
Explanation:

The two forms of oxygen found in the atmosphere are a diatomic molecular form that has chemical formula as O$ _2$ or oxygen, the life-giving gas that we breathe in to survive. 
Another  is a triatomic molecular form that has chemical formula as O$ _3$ called ozone gas, it protects us from harmful UV rays.
In water, oxygen is found as a compound with hydrogen molecules. The oxygen in water is dissolved oxygen used by aquatic animals and plants.
carbon dioxide has 2 molecules of oxygen with one molecule of carbon. It is formed by the reaction between carbon molecules and oxygen molecules during fermentation or respiration.
In the case of water and carbon dioxide, the oxygen does not exist independently but in association with other molecules. Whereas in the case of ozone and oxygen, the oxygen exists independently. Hence, the two forms of oxygen are ozone and oxygen.
The correct option is C (Ozone and Oxygen).

In which part of the atmosphere, ozone layer is present ?

zoology allotropy of oxygen ozone - a case study stratospheric pollution ozone and its depletion

  1. Stratosphere

  2. Troposphere

  3. Mesosphere

  4. Thermosphere

Show answer
Correct Option: A
Explanation:

The ozone layer or ozone shield refers to a region of Earth's stratosphere that absorbs most of the Sun's ultraviolet (UV) radiation. It contains high concentrations of ozone ($O _3$) relative to other parts of the atmosphere, although still very small relative to other gases in the stratosphere. 

Ozone is an important constituent of stratosphere because it:

zoology allotropy of oxygen ozone - a case study stratospheric pollution ozone and its depletion

  1. prevents the formation of smog over large cities

  2. removes poisonous gases of the atmosphere by reacting with them

  3. absorbs ultraviolet radiations which is harmful to human life

  4. destroys bacteria which are harmful to human life

Show answer
Correct Option: C
Explanation:
The stratospheric ozone layer absorbs ultraviolet light (UV) emitted by the sun. If the solar UV light were able to penetrate the stratosphere and troposphere and reach the earth’s surface, it would seriously damage our ecosystem.
And also it causes skin cancer, blindness, and cataracts.
Hence, the correct option is C.

Which of the following is responsible for peeling of ozone umbrella?

zoology allotropy of oxygen ozone - a case study stratospheric pollution ozone and its depletion

  1. PAN

  2. Coal burning

  3. CFCs

  4. ${CO} _{2}$

Show answer
Correct Option: C
Explanation:
$ The\quad correct\quad answer\quad is\quad "CFCs".$

$CFCs\quad drift\quad slowly\quad upward\quad to\quad the\quad stratosphere,where\quad they\quad are\quad broken\quad up\quad by\quad ultraviolet\quad radiation,releasing\quad chlorine\quad atoms,which\quad are\quad able\quad to\quad destroy\quad Ozone\quad molecules.The\quad chlorine\quad atom\quad then\quad reacts\quad with\quad anozone(O3)molecule\quad breaking\quad it\quad apart\quad and\quad so\quad destroying\quad the\quad ozone.$\\

$A\quad single\quad CFCs\quad molecule\quad can\quad destroy\quad 100,000\quad ozone\quad molecules.$

Which of the following statements is correct?

zoology allotropy of oxygen ozone - a case study stratospheric pollution ozone and its depletion

  1. Ozone hole is a hole formed in stratosphere from which ozone oozes out

  2. Ozone hole is a hole formed in troposphere from which ozone oozes out

  3. Ozone hole is thinning of ozone layer of stratosphere at some places

  4. Ozone hole means vanishing of ozone layer around the earth completely.

Show answer
Correct Option: C
Explanation:
The correct answer is Ozone hole is thinning of an ozone layer of the stratosphere at some places

The ozone hole is formed mainly from the two types of compounds which are responsible for the depletion of the ozone layer.
 These are:-
  • NO'S
  • CFC'S(Chlorofluorocarbons)
$N{ O } _{ 2 }+{ O } _{ 3 }\longrightarrow N{ O } _{ 2 }+{ O } _{ 2\\  }$
$C{ F } _{ 2 }C{ l } _{ 2 }\longrightarrow { CF } _{ 2 }Cl\quad +Cl$
$\dot { Cl } +{ O } _{ 3 }\longrightarrow Cl\dot { O } +{ O } _{ 2 }$
$Cl\quad +\dot { O\longrightarrow  } C\dot { l } +{ O } _{ 2 }$
These reactions occur in the stratosphere.

Reaction carried out by $N _2$ fixing microbes include
$2NH _3 + 3O _2 \rightarrow 2NO _2^- + 2H^+ + 2H _2O$            (i)
$2NO _2^- + O _2 \rightarrow 2NO _3^-$                                       (ii)
Which of the following statements about these equations is not true?

zoology bio-geo chemical cycles in nature nitrogen cycle biogeochemical cycles - gaseous nutrient cycles

  1. Step (i) is carried out by Nitrosomonas or Nitrosococcus

  2. Step (ii) is carried out by Nitrobacter

  3. Both step (i) and (ii) can be called nitrification.

  4. Bacteria carrying out these steps are usually photoautotrophs.

Show answer
Correct Option: D
Explanation:
Phototrophic bacteria are a group of bacteria, whose energy for growth is derived from sunlight and their source of carbon comes from carbon dioxide or organic carbon.
So, the correct option is 'Bacteria carrying out these steps are usually photoautotrophs'.

A farmer adds Azotobacter culture to soil before sowing maize. Which mineral element will be replenished by doing so?

zoology bio-geo chemical cycles in nature nitrogen cycle biogeochemical cycles - gaseous nutrient cycles

  1. N

  2. P

  3. K

  4. S

Show answer
Correct Option: A
Explanation:
Azotobacter is a free living bacteria in the soil. It helps some cereal crops like maize (Zea mays) in nitrogen fixation. The farmer adds Azotobacter culture to the maize field for enhancing the nitrogen element in the soil by the process of biological nitrogen-fixation. 
Thus, the correct answer is 'N.'

Which of the following is a non-symbiotic nitrogen fixing prokaryote?

zoology bio-geo chemical cycles in nature nitrogen cycle biogeochemical cycles - gaseous nutrient cycles

  1. Azotobacter

  2. Clostridium

  3. Beijerinckia

  4. All of these

Show answer
Correct Option: D
Explanation:

Two kinds of nitrogen-fixing bacteria are recognized. The first kind, the free-living (non-symbiotic) bacteria, includes the cyanobacteria (or blue-green algae), Anabaena and Nostoc and genera such as Azotobacter, Beijerinckia, and Clostridium. 

Thus, the correct answers is 'All of these.'