136. The thickness of the ozone layer is measured in
Decibels
Dobson unit
Meter
Armstrong unit
Answer.2. Dobson unit
Explanation:
The Dobson Unit is a way to describe how much ozone there would be in the column if it were all squeezed into a single layer.
137. Chlorofluorocarbon releases a chemical harmful to ozone is
Chlorine
Fluorine
Carbons
Nitrogen peroxide
Answer.1. Chlorine
Explanation:
Chlorine is a toxic chemical exerted from Chlorofluorocarbon. It contributes a major portion in depleting the ozone layer and also causing various health problems in human beings and animals.
The main cause of ozone depletion is manufactured chemicals, especially CFCs, these compounds reach the stratosphere by winds, where they release halogen atoms through photodissociation and cause the breakdown of ozone into oxygen.
138. In the breakdown of the ozone layer, the ozone (O3) directly reacts with
Ultraviolet light
Chlorine atoms
Oxygen atoms
CFC molecules
Answer.2. Chlorine atoms
Explanation:
In the breakdown of the ozone layer, the ozone directly reacts with chlorine atoms. Chlorine is a toxic chemical exerted from Chlorofluorocarbon. It contributes a major portion in depleting the ozone layer and also causes various health problems in human beings and animals.
The main cause of ozone depletion is manufactured chemicals, especially CFCs, these compounds reach the stratosphere by winds, where they release halogen atoms through photodissociation and cause the breakdown of ozone into oxygen.
139. A population is a group of
Individuals in a family
Individuals in a species
Communities in an ecosystem
Species in a community
Answer.2. Individuals in a species
Explanation:
Population refers to a group of individuals of the same species, occupying a defined area, and usually isolated to some degree from other similar groups. Sub-populations are members of population sub-groups who exhibit similar specific characteristics which differ from those in the whole study population.
140. The main cause of world population growth in 18th and 19th centuries was
Decrease in birth rates
Decrease in death rates
Industrial revolution
None of these
Answer.3. Industrial revolution
Explanation:
The main cause of world population growth in the 18th and 19th centuries was the Industrial revolution.
With industrialization, improvements in medical knowledge and public health, together with a more regular food supply, bring about a drastic reduction in the death rate but no corresponding decline in the birth rate. The result is a population explosion, as experienced in 19th-century Europe.
141. What is most important factor for the success of animal population?
Natality
Adaptability
Interspecies activity
Unlimited food
Answer.2. Adaptability
Explanation:
The most important factor for the success of the animal population on the earth is their ability to adapt to a given environment or show adaptability.
The process by which a species becomes fit for its survival in the environment is called adaptability.
When the environmental factors change the animals have to adapt to its surrounding by changing their temperature or metabolism over a period of time, Hence adaptability is the result of natural selection.
142. Human population growth is
Horizontal line
L-shaped curve
J-shaped curve
Parabola curve
Answer.1.
Explanation:
Human population growth is J-shaped curve.
J-shaped growth curve graph records the situation in which, in a new environment, the population density of an organism increases rapidly in an exponential or logarithmic form, but then stops abruptly as environmental resistance.
143. The main factors contributing to the decline in death rate in 20th century were
Improved agricultural practices and increased birth rates
Improved health care, sanitation and nutrition
Endemic poverty and low levels of education
European colonization and improved agriculture practices
Answer.2. Improved health care, sanitation and nutrition
Explanation:
The main cause of world population growth in the 18th and 19th centuries was the Industrial revolution.
With industrialization, improvements in medical knowledge, sanitation, nutrition, and public health, together with a more regular food supply, bring about a drastic reduction in the death rate but no corresponding decline in the birth rate. The result is a population explosion, as experienced in 19th-century Europe.
144. The world population in 2000 was approximately
5.1 billion
2.1 billion
6 billion
8 billon
Answer.3. 6 billion
Explanation:
The world population in 2000 was approximately 6 billion.
145. The average life expectancy around the world is currently
Stable
Increasing
Decreasing
Not changing
Answer.2. Increasing
Explanation:
The average life expectancy around the world is currently increasing. Globally, life expectancy has increased by more than 6 years between 2000 and 2019 – from 66.8 years in 2000 to 73.4 years in 2019.
146. Exponential growth in population occurs when there is
A great environment resistance
No environment resistance
A fixed carrying capacity
No biotic potential
Answer.3. No environment resistance
Explanation:
Exponential growth in population occurs when there is no environmental resistance. Because natural resources are limited, population growth is limited .
When resources are unlimited, a population can experience exponential growth, where its size increases at a greater and greater rate.
147. The disease which wiped out 33% of the population of Europe in the 12th and 13th centuries was
Cholera
Meningitis
Plague
Diphtheria
Answer.3. Plague
Explanation:
Plague disease wiped out 33% of the population of Europe in the 12th and 13th centuries.
The Black Death was a plague pandemic that devastated medieval Europe from 1347 to 1352 CE, killing an estimated 25-30 million people.
148. When human population is small, there is a greater chance of
Mutation
Gene flow
Genetic drift
Natural selection
Answer.3. Genetic drift
Explanation:
Genetic drift is a mechanism of evolution in which allele frequencies of a population change over generations due to chance (sampling error). Genetic drift occurs in all populations of non-infinite size, but its effects are strongest in small populations.
149. Which of the following is a problem not associated with population growth?
Increased resource consumption
Environmental pollution
Food and energy shortages
None of these
Answer.4. None of these
Explanation:
Fatal Effects of Overpopulation
Depletion of Natural Resources
Degradation of Environment
Conflicts and Wars
Rise in Unemployment
High Cost of Living
Pandemics and Epidemics
Malnutrition, Starvation and Famine
Water Shortage
Food and energy shortages
150. Unrestricted reproductive capacity in a population is called
Birth rate
Carrying capacity
Fertility rate
Biotic potential
Answer.4. Biotic potential
Explanation:
Unrestricted reproductive capacity is called biotic potential.
The biotic potential is described by the unrestricted growth of populations resulting in the maximum growth of that population. The biotic potential is the highest possible vital index of a species; therefore, when the species has its highest birthrate and lowest mortality rate.
